Crushing waste coral concrete into recycled aggregates to create recycled coral aggregate concrete(RCAC)contributes to sustainable construction development on offshore islands and reefs.To investigate the impact of re...Crushing waste coral concrete into recycled aggregates to create recycled coral aggregate concrete(RCAC)contributes to sustainable construction development on offshore islands and reefs.To investigate the impact of recycled coral aggregate on concrete properties,this study performed a comprehensive analysis of the physical properties of recycled coral aggregate and the basic mechanical properties and microstructure of RCAC.The test results indicate that,compared to coral debris,the crushing index of recycled coral aggregate was reduced by 9.4%,while porosity decreased by 33.5%.Furthermore,RCAC retained the early strength characteristics of coral concrete,with compressive strength and flexural strength exhibiting a notable increase as the water-cement ratio decreased.Under identical conditions,the compressive strength and flexural strength of RCAC were 12.7% and 2.5% higher than coral concrete's,respectively,with porosity correspondingly reduced from 3.13% to 5.11%.This enhancement could be attributed to the new mortar filling the recycled coral aggregate.Scanning electron microscopy(SEM)analysis revealed three distinct interface transition zones within RCAC,with the‘new mortar-old mortar’interface identified as the weakest.The above findings provided a reference for the sustainable use of coral concrete in constructing offshore islands.展开更多
In this study,the efects of diferent heat treatment process parameters on the microstructure and mechanical properties of Al-12Si-5Cu-1.1Mg-2.3Ni-0.3La alloy were explored.Research showed that eutectic Si underwent th...In this study,the efects of diferent heat treatment process parameters on the microstructure and mechanical properties of Al-12Si-5Cu-1.1Mg-2.3Ni-0.3La alloy were explored.Research showed that eutectic Si underwent three stages during solution treatment:difusing,spheroidization and coarsening.As the solution temperature and time increased,the size of eutectic Si showed a trend of frst decreasing and then increasing.Compared with the heat treatment time,the heat treatment temperature had a more signifcant efect on the mechanical properties.The coarsening of microstructure was the main reason for the deterioration of mechanical properties.The Al_(3)Ti and Al_(3)CuNiLa in the microstructure after aging can signifcantly improve the mechanical properties of the alloy.The Al_(11)La_(3) with secondary precipitation occurred in the La-rich phase.The addition of La inhibited the growth of coherent/semi-coherentθandβphases,which was very benefcial for the improvement of high-temperature strength.Under the optimal heat treatment process parameters of 500℃×4 h+190℃×4 h,the ultimate tensile strength(UTS)of the alloy reached 366.65 MPa.The high-temperature strength and elongation of the alloy reached 101.98 MPa and 13.77%at 350℃,respectively.展开更多
The microstructures and mechanical properties of Al-8.3Zn-3.3Cu-2.2Mg alloys prepared via hot extrusion and liquid forging methods were investigated.Results show that based on DEFORM simulation analysis,the optimal ho...The microstructures and mechanical properties of Al-8.3Zn-3.3Cu-2.2Mg alloys prepared via hot extrusion and liquid forging methods were investigated.Results show that based on DEFORM simulation analysis,the optimal hot extrusion parameters are determined as ingot initial temperature of 380°C and extrusion speed of 3 mm/s.The hot-extruded aluminum alloy after T6 heat treatment presents superior mechanical properties with yield strength of 519.6 MPa,ultimate tensile strength of 582.1 MPa,and elongation of 11.0%.Compared with the properties of gravity-cast and liquid-forged alloys,the yield strength of hot-extruded alloy increases by 30.8%and 4.9%,and the ultimate tensile strength improves by 43.5%and 10.2%,respectively.The significant improvement in tensile strength of the hot-extruded alloys is attributed to the elimination of casting defects and the refinement of matrix grain and eutectic phases.In addition,the hot-extruded alloy demonstrates superior plasticity compared with the liquid-forged alloy.This is because severe plastic deformation occurs during hot extrusion,which effectively breaks and disperses the eutectic phases,facilitating the dissolution and precipitation of the second phases and inhibiting the microcrack initiation.展开更多
Modification of 6061 aluminum alloy was conducted through composite addition of cerium-rich rare earths and Al-Ti-B.Results show that the composite addition of Al-Ti-B and Ce/La element at a specific ratio notably pro...Modification of 6061 aluminum alloy was conducted through composite addition of cerium-rich rare earths and Al-Ti-B.Results show that the composite addition of Al-Ti-B and Ce/La element at a specific ratio notably promotes the refinement of the alloy's grains.Ce and La elements are combined with Si and other elements to form rare earth phases,improving the morphology and distribution of precipitates and mitigating the adverse effects ofβ-Fe phases on the microstructure and mechanical properties of alloy.However,excessive rare earth content poses challenges;it not only leads to a decrease in Mg-Si strengthening phase by binding with Si but also promotes the formation of larger or numerous rare earth phases that may act as initiation points for cracks,thereby impeding the improvement of the structure and performance of alloy.The composite addition of cerium-rich rare earths and Al-Ti-B not only preserves the strength of the alloy but also significantly enhances the plasticity of the 6061 as-cast alloy.At a composite addition ratio of Al-Ti-B:RE=2:1,the newly developed 6061-RE aluminum alloy exhibits increased average elongation by 50%and 45%in its as-cast and homogenized states,respectively,compared to the baseline 6061 alloy,facilitating subsequent deformation processing.After solution treatment at 540℃for 1 h and aging at 180℃for 5 h,the average ultimate tensile strength and yield strength of 6061-RE alloys reach 313.2 and 283.1 MPa,increased by 12.3%and 14.5%compared with those of the original alloy,respectively,and the average elongation is improved by 41%.展开更多
Hot isostatic pressing (HIP) temperature has a significant impact on the service performance of powder metallurgy titanium alloys. In this study, a high-temperature titanium alloy, Ti-6.5Al-3.5Mo-1.5Zr-0.3Si, was prep...Hot isostatic pressing (HIP) temperature has a significant impact on the service performance of powder metallurgy titanium alloys. In this study, a high-temperature titanium alloy, Ti-6.5Al-3.5Mo-1.5Zr-0.3Si, was prepared under different HIP temperatures (880–1000℃), and the microstructural evolution and mechanical properties were systematically investigated. The results demonstrated that the HIPed alloys were predominantly composed of more than 80 vol.% α phase and a small amount of β phase, and their phase compositions were basically unaffected by the HIP temperatures. Under the typical single-temperature-maintained HIP (STM-HIP) regime, the microstructure of alloy significantly coarsened as the HIP temperature increased, and the alloy strength exhibited an obvious linear negative correlation with the HIP temperature. On the basis of Hall–Petch relation, the prediction model of grain size was established, and the mathematical equation between HIP temperature and grain size (d=M(T_(HIP-N)^(-2))) was deduced. Furthermore, a possible evolution mechanism of microstructure was proposed, which could be divided into the decomposition of initial α′ martensite for as-received powder, formation of the globular α grains in prior particle boundaries (PPBs) region, and precipitation of the platelet α grains in non-PPBs region. For these alloys prepared by the dual-temperature-maintained HIP (DTM-HIP) regime, although their tensile properties were comparable to that of alloy prepared by STM-HIP regime with same high-temperature holding stage, higher proportion of globular α grains occurred due to more recrystallization nucleation during the low-temperature holding stage, which probably provided a solution for improving the dynamic service performance of HIPed alloys.展开更多
Electrolytic copper foil has gained significant attention as an essential component in lithium-ion batteries(LIBs),printed circuit boards(PCBs),and chip packaging substrates(CPSs)applications.With the advancement of L...Electrolytic copper foil has gained significant attention as an essential component in lithium-ion batteries(LIBs),printed circuit boards(PCBs),and chip packaging substrates(CPSs)applications.With the advancement of LIBs towards higher energy densities and the increasing density of electronic components on circuits,copper foil is required to have demanding properties,such as extremely thin thickness and extremely high tensile strength.This comprehensive review firstly summarizes recent progress on the fabrication of electrolytic copper foil,and the effects of process parameters,cathode substrate,and additives on the electrodeposition behavior,microstructure,and properties of copper foil are discussed in detail.Then the regulation strategies of mechanical properties of electrolytic copper foil are also summarized,including the formation of nanotwins and texture.Furthermore,the recent advances in novel electrolytic copper foils,such as composite foils and extra-thin copper foils,are also overviewed.Lastly,the remaining challenges and perspectives on the further development of electrolytic copper foils are presented.展开更多
This article studies the effects of different Sn contents on the melting characteristics,microstructure,and mechanical properties of brazed joints of low-silver BAg5CuZn-0.3 wt.%La brazing material.A differential ther...This article studies the effects of different Sn contents on the melting characteristics,microstructure,and mechanical properties of brazed joints of low-silver BAg5CuZn-0.3 wt.%La brazing material.A differential thermal analyzer(HCR-1)was used to measure the solid-liquidus temperature of BAg5CuZn-0.3 wt.%La-xSn brazing material.The results show that the addition of Sn element effect-ively reduces the solid-liquidus temperature of BAg5CuZn-0.3 wt.%La brazing material.Microstructural characterization was con-ducted using scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),etc.Analysis re-veals that progressive aggregation and precipitation of Cu-Sn intermetallic compounds occur with increasing Sn content,leading to microstructural coarsening.Notably,severe grain coarsening is observed when the Sn content reaches 4 wt.%.Shear testing of the BAg5CuZn-0.3 wt.%La-xSn brazing joints reveals a non-monotonic trend in joint strength:as Sn content increases,the shear strength initially improves but subsequently deteriorates after reaching an optimal value.展开更多
The high-strength Mg-7Sn alloys(wt.%)with a heterogeneous grain structure were prepared by low-temperature extrusion(230°C)with the extrusion ratio of 9:1(9E230)and 17:1(17E230).The two extruded alloys contained ...The high-strength Mg-7Sn alloys(wt.%)with a heterogeneous grain structure were prepared by low-temperature extrusion(230°C)with the extrusion ratio of 9:1(9E230)and 17:1(17E230).The two extruded alloys contained fine dynamic recrystallization(DRX)grains(FG)and coarse un DRX grains(CG).The difference in deformability between CG and FG leads to the formation of heterogeneous grain structure.The average grain size and basal texture intensities increased while the volume fraction of CG decreased with increasing extrusion ratio.Tensile testing results indicated that the extruded 17E230 alloy exhibited higher tensile strengths than 9E230 alloy,whose tensile yield strength(σ_(0.2)),ultimate tensile strengths(σ_(b)),and elongation to failure(ε_(f))were 231.1 MPa,319.5MPa,and 12.54%respectively.The high tensile strengths of the extruded alloy mainly originated from grain refinement,texture strengthening,precipitation strengthening from a great number of nano-scale Mg_(2)Sn phases,solid solution strengthening and hetero-deformation induced(HDI)strengthening,while the good ductility of the alloy was also mainly attributed to grain refinement,activation of the non-basal slip systems and HDI hardening.展开更多
Thin walls of an AZ91 magnesium alloy with fine equiaxed grains were fabricated via cold arc-based wire arc additive manufacturing(CA-WAAM),and the droplet transfer behaviours,microstructures,and mechanical properties...Thin walls of an AZ91 magnesium alloy with fine equiaxed grains were fabricated via cold arc-based wire arc additive manufacturing(CA-WAAM),and the droplet transfer behaviours,microstructures,and mechanical properties were investigated.The results showed that the cold arc process reduced splashing at the moment of liquid bridge breakage and effectively shortened the droplet transfer period.The microstructures of the deposited samples exhibited layered characteristics with alternating distributions of coarse and fine grains.During layer-by-layer deposition,the β-phase precipitated and grew preferentially along grain boundaries,while the fineη-Al_(8)Mn_(5)phase was dispersed in the α-Mg matrix.The mechanical properties of the CA-WAAM deposited sample showed isotropic characteristics.The ultimate tensile strength and elongation in the building direction(BD)were 282.7 MPa and 14.2%,respectively.The microhardness values of the deposited parts were relatively uniform,with an average value of HV 69.6.展开更多
The regulation of sintering temperature in spark plasma sintering enables the achievement of grain refinement,phase control,and performance enhancement in the preparation of AZ91D magnesium alloy.This study investigat...The regulation of sintering temperature in spark plasma sintering enables the achievement of grain refinement,phase control,and performance enhancement in the preparation of AZ91D magnesium alloy.This study investigates the influence of sintering temperature on microstructural evolution and mechanical properties of the AZ91D alloy.Microstructural analysis was conducted using scanning electron microscopy,electron backscatter diffraction,and X-ray diffraction.Microscopic structures and mechanical behaviors were examined through hardness and tensile tests.Elevated sintering temperatures resulted in reduced secondary phase content,leading to a decrease in mechanical performance.The alloy exhibited optimal mechanical properties at 320℃.The nanoparticle coarsening process and particle evolution during sintering were simulated using phase field methods.By optimizing the sintering temperature,precise control over microstructural and textural evolution can be achieved,facilitating the attainment of desired hardness levels and mechanical properties.展开更多
Low-oxygen TZM alloy(oxygen content of 0.03vol%)was subjected to solid-solution heat treatment at various temperatures followed by quenching.Results show that the tensile strength of the alloy gradually decreases with...Low-oxygen TZM alloy(oxygen content of 0.03vol%)was subjected to solid-solution heat treatment at various temperatures followed by quenching.Results show that the tensile strength of the alloy gradually decreases with the increase in solidsolution temperature,and the elongation first increases and then decreases.The the amount of nanoscale Ti-rich phases precipitated in low-oxygen TZM alloys gradually increases with the increase in solid-solution temperature.Special strip-shaped Ti-rich areas appear in the samples solidified at 1200 and 1300℃.The nanoscale Ti-rich phases ensure the uniform distribution of dislocations throughout TZM alloy,while significantly improving the plasticity of low-oxygen TZM alloy samples.展开更多
The microstructure,micro-hardness,and tensile properties of interface between hot isostatic pressing densified low alloy steel and Inconel 690 cladding were investigated during the aging process at 600℃.The results s...The microstructure,micro-hardness,and tensile properties of interface between hot isostatic pressing densified low alloy steel and Inconel 690 cladding were investigated during the aging process at 600℃.The results show that the interface region can be divided into four zones from base metal to deposited metal:carbon-depleted zone(CDZ),partial melting zone(PMZ),planar growth zone(PGZ),and brownish feature zone(BFZ).Dimensions of these zones do not significantly change during aging.However,type I carbides noticeably increase in size in the PMZ,and precipitates clearly occur in the PGZ.The main reason for their growth and occurrence is continuous carbon migration.The highest micro-hardness appears in the PGZ and BFZ regions,which is related to carbon accumulation and precipitates in these regions.Tensile failure occurs on the base metal side due to the high strength mismatch between these two materials.The CDZ,composed of only ferrite,has lower strength and fractures at the boundary between CDZ and base metal.The ultimate tensile strength decreases by only 50 MPa after aging for 1500 h,and the interface region maintains high strength without significant deformation.展开更多
(TiZrHf)_(50)Ni_(30)Cu_(20-x)Co_(x)(x=2,4,6,at%)high-entropy high-temperature shape memory alloys were fabricated by watercooled copper crucible in a magnetic levitation vacuum melting furnace,and the effects of Co co...(TiZrHf)_(50)Ni_(30)Cu_(20-x)Co_(x)(x=2,4,6,at%)high-entropy high-temperature shape memory alloys were fabricated by watercooled copper crucible in a magnetic levitation vacuum melting furnace,and the effects of Co content on microstructure and mechanical properties were investigated.The results indicate that the grain size of the alloy decreases with increasing the Co content.In the as-cast state,the alloy consists primarily of the B19′phase,with a trace of B2 phase.The fracture morphology is predominantly composed of the B19′phase,whereas the B2 phase is nearly absent.Increasing the Co content or reducing the sample dimensions(d)markedly enhance the compressive strength and ductility of the alloy.When d=2 mm,the(TiZrHf)_(50)Ni_(30)Cu_(14)Co_(6) alloy demonstrates the optimal mechanical properties,achieving a compressive strength of 2142.39±1.8 MPa and a plasticity of 17.31±0.3%.The compressive cyclic test shows that with increasing the compressive strain,the residual strain of the(TiZrHf)_(50)Ni_(30)Cu_(14)Co_(6) alloy increases while the recovery ability declines.The superelastic recovery capability of the alloy is continuously enhanced.The superelastic recovery rate increases from 1.36%to 2.12%,the residual strain rate rises from 1.79%to 5.52%,the elastic recovery rate ascends from 3.86%to 7.36%,while the total recovery rate declines from 74.48%to 63.20%.展开更多
The transient liquid-phase(TLP)diffusion bonding of GH5188 with a BNi-5 interlayer was focused on.Parameters were chosen and optimized for GH5188 alloy according to the TLP joining mechanism.The microstructure evoluti...The transient liquid-phase(TLP)diffusion bonding of GH5188 with a BNi-5 interlayer was focused on.Parameters were chosen and optimized for GH5188 alloy according to the TLP joining mechanism.The microstructure evolution and mechanical properties of the joints were studied.Results show that the relatively complete isothermal solidification zone(ISZ)ensures a reliable connection of the base metal(BM).Within the temperature range of 1110–1190°C,higher bonding temperatures can widen ISZ and promote joint composition homogenization,thus improving mechanical properties.However,the increase in precipitated phase has an adverse effect on the mechanical properties of the joint.The maximum shear strength,reaching 482 MPa,is achieved at 1130°C,representing 84.6%of BM strength.Within the pressure range of 5–15 MPa,both precipitated phases in adiabatic solidification zone(ASZ)and voids generated by partial melting increase.On the contrary,their sizes decrease significantly under higher bonding pressure,resulting in an upward trend in alloy mechanical properties.The maximum shear strength of 490 MPa is attained at a bonding pressure of 15 MPa.The joint exhibits a typical mixed fracture pattern,with the small brittle M_(23)C_(6) phase and voids significantly impacting mechanical properties.Nano-indentation tests indicate that ASZ is a potential source of cracks.展开更多
The effects of the co-addition of Ni and Zn on the microstructure and mechanical properties of the extruded Mg-6.84Y2.45Cu(MYC,wt%)alloy were researched.Results show that the as-cast Mg-6.79Y-1.21Cu-1.12Ni-1.25Zn(MYCN...The effects of the co-addition of Ni and Zn on the microstructure and mechanical properties of the extruded Mg-6.84Y2.45Cu(MYC,wt%)alloy were researched.Results show that the as-cast Mg-6.79Y-1.21Cu-1.12Ni-1.25Zn(MYCNZ,wt%)alloy consists of theα-Mg,a few Y-rich phases,lamellar 18R-long period stacking ordered(LPSO)phase,and granular Mg_(2)(Cu,Ni,Zn)phase.After the homogenization process,phase transformation occurs in MYCNZ alloy.Some 18R-LPSO phases at the grain boundary are transformed into the thin striped 14H-LPSO phase in the grains.After extrusion,the amount,morphology,and distribution of the second phase are changed,and the grain size of the extruded MYCNZ alloy is significantly reduced to approximately 2.62µm.Additionally,a weaker basal texture is formed in the extruded MYCNZ alloy.The tensile results indicate that the co-addition of Ni and Zn significantly enhances the tensile strength of the extruded MYC alloy while maintaining good ductility.The tensile yield strength(σ_(0.2)),ultimate tensile strength(σ_(b)),and elongation to failure(ε_(L))of the extruded MYCNZ alloy are 266.9 MPa,299.8 MPa,and 20.1%,respectively.This alloy has a good strength-plastic synergistic effect.The excellent tensile strength of the extruded MYCNZ alloy at room temperature is mainly due to grain refinement and the second phase strengthening effect,and its outstanding ductility is ascribed to the texture weakening and activation of non-basal slips.展开更多
AZ31/Al/Ta composites were prepared using the vacuum hot compression bonding(VHCB)method.The effect of hot compressing temperature on the interface microstructure evolution,phase constitution,and shear strength at the...AZ31/Al/Ta composites were prepared using the vacuum hot compression bonding(VHCB)method.The effect of hot compressing temperature on the interface microstructure evolution,phase constitution,and shear strength at the interface was investigated.Moreover,the interface bonding mechanisms of the AZ31/Al/Ta composites during the VHCB process were explored.The results demonstrate that as the VHCB temperature increases,the phase composition of the interface between Mg and Al changes from the Mg-Al brittle intermetallic compounds(Al_(12)Mg_(17)and Al_(3)Mg_(2))to the Al-Mg solid solution.Meanwhile,the width of the Al/Ta interface diffusion layer at 450℃increases compared to that at 400℃.The shear strengths are 24 and 46 MPa at 400 and 450℃,respectively.The interfacial bonding mechanism of AZ31/Al/Ta composites involves the coexistence of diffusion and mechanical meshing.Avoiding the formation of brittle phases at the interface can significantly improve interfacial bonding strength.展开更多
The microstructure and texture evolution of Mg-xAl-1Zn-1Y-0.1Mn alloys are systematically analyzed.There is no effect of Al addition on grain refinement in the Mg-1Zn-1Y-0.1Mn alloy,but the addition of 0.5 wt.%or more...The microstructure and texture evolution of Mg-xAl-1Zn-1Y-0.1Mn alloys are systematically analyzed.There is no effect of Al addition on grain refinement in the Mg-1Zn-1Y-0.1Mn alloy,but the addition of 0.5 wt.%or more Al element dramatically changes texture from a weak texture to a strong basal texture.The predominant second phase particle of Mg_(3)Zn_(3)Y_(2) phase in the Mg-1Zn-1Y-0.1Mn alloy changes to Al_(2)Y phase by the addition of only 0.1 wt.%Al element,and the concentrations of dissolved Y element in the 0Al,0.1Al,0.3Al,0.5Al and 1Al alloys are 0.50,0.31,0.23,0.15 and 0.06 wt.%,respectively.Although the 0.5 wt.%or more Al-added alloys have higher Schmid factor for prismatic(a)slip than the 0.3 wt.%or less Al-added alloys,the lower Al containing alloys show much higher activity of prismatic (a)slip than the higher Al containing alloys.It demonstrates that the addition of high amount of Al element in Mg-Zn-RE alloy dramatically decrease the dissolved Y element,resulting in a significant deterioration of activity of prismaticslip and consequently a poor formability at room temperature.展开更多
The fracture mechanisms of coarse-grained heat-affected zone(CGHAZ)for Mg and Mg–Ca deoxidized high-strength low-alloy(HSLA)steels after high heat input welding(HHIW)were investigated based on the microstructures,cra...The fracture mechanisms of coarse-grained heat-affected zone(CGHAZ)for Mg and Mg–Ca deoxidized high-strength low-alloy(HSLA)steels after high heat input welding(HHIW)were investigated based on the microstructures,crack behaviors and mechanical properties.Compared to Mg–Ca steel,the proportion of intergranular acicular ferrites(IAFs)and polygonal ferrites(PFs)in Mg steel increases from 59.97%to 90.16%.The high-angle grain boundaries(HAGBs)and geometrically necessary dislocations density increase from 55.5%and 4.30×10^(14) m^(-2)to 70.4%and 5.48×10^(14) m^(–2),respectively,while effective grain size decreases from 9.46 to 8.12μm.The area fraction of radial zone in Mg steel decreases from 80.8%to 37.7%and cleavage plane is smaller with more curved and finer tearing ridges.The inclusions distributed at the center of cleavage planes and along river lines can serve as crack initiation sites.The zigzag pattern of primary crack propagation path has width of 476μm and the length of secondary cracks remains below 10μm.These cracks are deflected or arrested by IAFs,PFs and HAGBs,and tend to propagate along{110}plane family.These factors contribute to superior overall mechanical properties of Mg steel,especially increasing low-temperature impact toughness from 23 to 175 J.展开更多
The microstructure evolution and mechanical properties of a Fe-0.12C-0.2Si-1.6Mn-0.3Cr-0.0025B(wt.%)steel with different initial microstructures,i.e.,hot rolled(HR)and cold rolled-annealed(CRA),were studied through op...The microstructure evolution and mechanical properties of a Fe-0.12C-0.2Si-1.6Mn-0.3Cr-0.0025B(wt.%)steel with different initial microstructures,i.e.,hot rolled(HR)and cold rolled-annealed(CRA),were studied through optical microscopy,scanning electron microscopy,electron channeling contrast imaging,microhardness and room temperature uniaxial tensile tests.After water quenching from 930℃ to room temperature,a fully martensitic microstructure was obtained in both as-quenched HR and CRA specimens,which shows a microhardness of 480±5 HV,and no significant difference in microstructure and microhardness was observed.Tensile test results show that the product of tensile strength and total elongation(UTS×TE)of the as-quenched HR specimen,i.e.,24.1 GPa%,is higher than that of the as-quenched CRA specimen,i.e.,18.9 GPa%.While,after being tempered at 300℃,the martensitic microstructures and mechanical properties of the two as-quenched specimens change significantly due to the synergy role of the matrix phase softening and the precipitation strengthening.Concerning the maximum UTS×TE,it is 18.9 GPa%obtained in the as-quenched CRA one,while that is 24.4 GPa%obtained in the HR specimen after tempered at 300℃ for 5 min.展开更多
The TiNbV_(0.5)Ta_(0.5)Cr_(x)(x=0,0.1,0.2,0.5)refractory high-entropy alloys(RHEAs)with an excellent combination of ductility and strength were designed and prepared for high-temperature applications.The yield strengt...The TiNbV_(0.5)Ta_(0.5)Cr_(x)(x=0,0.1,0.2,0.5)refractory high-entropy alloys(RHEAs)with an excellent combination of ductility and strength were designed and prepared for high-temperature applications.The yield strength,ultimate tensile strength,and elongation of the TiNbV_(0.5)Ta_(0.5)Cr_(0.1) alloy were 878 MPa,928 MPa,and 21.6%,respectively.Important issues of microstructure evolution,precipitation process,and their impact on mechanical properties were concerned.Then,the effect of Cr content on the mechanical properties of TiNbV_(0.5)Ta_(0.5)Cr_(x) alloys was evaluated through a quantitative analysis of the strengthening mechanism,which elucidated the trade-offrelationship between solid solution strengthening and precipitation strengthening in RHEA.The microstructure evolution of the TiNbV_(0.5)Ta_(0.5)Cr_(x) alloys involved the formation and interconversion of titanium allotropes(α-Ti and β-Ti)and the precipitation of the Laves phase.Significant embrittlement was induced by the preferential precipitation of α-Ti on the grain boundary.The TiNbV_(0.5)Ta_(0.5)Cr_(x) alloys exhibited an incubation period for Laves phase precipitation,which was related to the Cr content in the alloy.The Laves phase preferentially nucleated next to α-Ti due to the redistribution of elements during the α-Ti precipitation process.The precipitation of the Laves phase played an important role in enhancing the strength of the TiNbV_(0.5)Ta_(0.5)Cr_(x) alloys.展开更多
基金Funded by Natural Science Foundation of Guangxi(No.2025GXNSFBA069565)Guangxi Science and Technology Program(No.AD25069101)Guangxi Bagui Scholars Fund。
文摘Crushing waste coral concrete into recycled aggregates to create recycled coral aggregate concrete(RCAC)contributes to sustainable construction development on offshore islands and reefs.To investigate the impact of recycled coral aggregate on concrete properties,this study performed a comprehensive analysis of the physical properties of recycled coral aggregate and the basic mechanical properties and microstructure of RCAC.The test results indicate that,compared to coral debris,the crushing index of recycled coral aggregate was reduced by 9.4%,while porosity decreased by 33.5%.Furthermore,RCAC retained the early strength characteristics of coral concrete,with compressive strength and flexural strength exhibiting a notable increase as the water-cement ratio decreased.Under identical conditions,the compressive strength and flexural strength of RCAC were 12.7% and 2.5% higher than coral concrete's,respectively,with porosity correspondingly reduced from 3.13% to 5.11%.This enhancement could be attributed to the new mortar filling the recycled coral aggregate.Scanning electron microscopy(SEM)analysis revealed three distinct interface transition zones within RCAC,with the‘new mortar-old mortar’interface identified as the weakest.The above findings provided a reference for the sustainable use of coral concrete in constructing offshore islands.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.U2241232,U2341253 and 52375317)the National Key R&D Program of China(No.2022YFB3404204).
文摘In this study,the efects of diferent heat treatment process parameters on the microstructure and mechanical properties of Al-12Si-5Cu-1.1Mg-2.3Ni-0.3La alloy were explored.Research showed that eutectic Si underwent three stages during solution treatment:difusing,spheroidization and coarsening.As the solution temperature and time increased,the size of eutectic Si showed a trend of frst decreasing and then increasing.Compared with the heat treatment time,the heat treatment temperature had a more signifcant efect on the mechanical properties.The coarsening of microstructure was the main reason for the deterioration of mechanical properties.The Al_(3)Ti and Al_(3)CuNiLa in the microstructure after aging can signifcantly improve the mechanical properties of the alloy.The Al_(11)La_(3) with secondary precipitation occurred in the La-rich phase.The addition of La inhibited the growth of coherent/semi-coherentθandβphases,which was very benefcial for the improvement of high-temperature strength.Under the optimal heat treatment process parameters of 500℃×4 h+190℃×4 h,the ultimate tensile strength(UTS)of the alloy reached 366.65 MPa.The high-temperature strength and elongation of the alloy reached 101.98 MPa and 13.77%at 350℃,respectively.
基金Natural Science Foundation of Shandong Province of China(ZR2023QE193)。
文摘The microstructures and mechanical properties of Al-8.3Zn-3.3Cu-2.2Mg alloys prepared via hot extrusion and liquid forging methods were investigated.Results show that based on DEFORM simulation analysis,the optimal hot extrusion parameters are determined as ingot initial temperature of 380°C and extrusion speed of 3 mm/s.The hot-extruded aluminum alloy after T6 heat treatment presents superior mechanical properties with yield strength of 519.6 MPa,ultimate tensile strength of 582.1 MPa,and elongation of 11.0%.Compared with the properties of gravity-cast and liquid-forged alloys,the yield strength of hot-extruded alloy increases by 30.8%and 4.9%,and the ultimate tensile strength improves by 43.5%and 10.2%,respectively.The significant improvement in tensile strength of the hot-extruded alloys is attributed to the elimination of casting defects and the refinement of matrix grain and eutectic phases.In addition,the hot-extruded alloy demonstrates superior plasticity compared with the liquid-forged alloy.This is because severe plastic deformation occurs during hot extrusion,which effectively breaks and disperses the eutectic phases,facilitating the dissolution and precipitation of the second phases and inhibiting the microcrack initiation.
基金Subproject of Inner Mongolia Autonomous Region Key Research and Development and Achievement Transformation Plan Project(2023YFDZ0064,2023KJHZ0020,2022YFDZ0097)Natural Science Foundation of Inner Mongolia Autonomous Region of China(2022QN05040)+1 种基金Basic Research Funds for Directly Affiliated Universities in Inner Mongolia Autonomous Region(JY20220093)Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region(NJYT24008)。
文摘Modification of 6061 aluminum alloy was conducted through composite addition of cerium-rich rare earths and Al-Ti-B.Results show that the composite addition of Al-Ti-B and Ce/La element at a specific ratio notably promotes the refinement of the alloy's grains.Ce and La elements are combined with Si and other elements to form rare earth phases,improving the morphology and distribution of precipitates and mitigating the adverse effects ofβ-Fe phases on the microstructure and mechanical properties of alloy.However,excessive rare earth content poses challenges;it not only leads to a decrease in Mg-Si strengthening phase by binding with Si but also promotes the formation of larger or numerous rare earth phases that may act as initiation points for cracks,thereby impeding the improvement of the structure and performance of alloy.The composite addition of cerium-rich rare earths and Al-Ti-B not only preserves the strength of the alloy but also significantly enhances the plasticity of the 6061 as-cast alloy.At a composite addition ratio of Al-Ti-B:RE=2:1,the newly developed 6061-RE aluminum alloy exhibits increased average elongation by 50%and 45%in its as-cast and homogenized states,respectively,compared to the baseline 6061 alloy,facilitating subsequent deformation processing.After solution treatment at 540℃for 1 h and aging at 180℃for 5 h,the average ultimate tensile strength and yield strength of 6061-RE alloys reach 313.2 and 283.1 MPa,increased by 12.3%and 14.5%compared with those of the original alloy,respectively,and the average elongation is improved by 41%.
基金support from CAS Project for Young Scientists in Basic Research(YSBR-025)and the Technology Innovation(RCJJ-145-24-39)R.P.Guo acknowledges the financial support from the National Natural Science Foundation of China(No.52401104)+1 种基金the Fundamental Research Program of Shanxi Province(No.202203021221072)the China Postdoctoral Science Foundation(No.2024M753298).
文摘Hot isostatic pressing (HIP) temperature has a significant impact on the service performance of powder metallurgy titanium alloys. In this study, a high-temperature titanium alloy, Ti-6.5Al-3.5Mo-1.5Zr-0.3Si, was prepared under different HIP temperatures (880–1000℃), and the microstructural evolution and mechanical properties were systematically investigated. The results demonstrated that the HIPed alloys were predominantly composed of more than 80 vol.% α phase and a small amount of β phase, and their phase compositions were basically unaffected by the HIP temperatures. Under the typical single-temperature-maintained HIP (STM-HIP) regime, the microstructure of alloy significantly coarsened as the HIP temperature increased, and the alloy strength exhibited an obvious linear negative correlation with the HIP temperature. On the basis of Hall–Petch relation, the prediction model of grain size was established, and the mathematical equation between HIP temperature and grain size (d=M(T_(HIP-N)^(-2))) was deduced. Furthermore, a possible evolution mechanism of microstructure was proposed, which could be divided into the decomposition of initial α′ martensite for as-received powder, formation of the globular α grains in prior particle boundaries (PPBs) region, and precipitation of the platelet α grains in non-PPBs region. For these alloys prepared by the dual-temperature-maintained HIP (DTM-HIP) regime, although their tensile properties were comparable to that of alloy prepared by STM-HIP regime with same high-temperature holding stage, higher proportion of globular α grains occurred due to more recrystallization nucleation during the low-temperature holding stage, which probably provided a solution for improving the dynamic service performance of HIPed alloys.
基金supported by the National Key R&D Plan Program of China(No.2021YFB3400800)Henan Key Research and Development Program(No.231111241000)+1 种基金the Joint Fund of Henan Province Science and Technology R&D Program(No.225200810026)Zhongyuan Scholar Workstation Funded Program(No.224400510025).
文摘Electrolytic copper foil has gained significant attention as an essential component in lithium-ion batteries(LIBs),printed circuit boards(PCBs),and chip packaging substrates(CPSs)applications.With the advancement of LIBs towards higher energy densities and the increasing density of electronic components on circuits,copper foil is required to have demanding properties,such as extremely thin thickness and extremely high tensile strength.This comprehensive review firstly summarizes recent progress on the fabrication of electrolytic copper foil,and the effects of process parameters,cathode substrate,and additives on the electrodeposition behavior,microstructure,and properties of copper foil are discussed in detail.Then the regulation strategies of mechanical properties of electrolytic copper foil are also summarized,including the formation of nanotwins and texture.Furthermore,the recent advances in novel electrolytic copper foils,such as composite foils and extra-thin copper foils,are also overviewed.Lastly,the remaining challenges and perspectives on the further development of electrolytic copper foils are presented.
基金the support from Jinhua Sanhuan Welding Materials Company LimitedSchool of Materials Science and Engineering,Nanjing University of Science and Technology.
文摘This article studies the effects of different Sn contents on the melting characteristics,microstructure,and mechanical properties of brazed joints of low-silver BAg5CuZn-0.3 wt.%La brazing material.A differential thermal analyzer(HCR-1)was used to measure the solid-liquidus temperature of BAg5CuZn-0.3 wt.%La-xSn brazing material.The results show that the addition of Sn element effect-ively reduces the solid-liquidus temperature of BAg5CuZn-0.3 wt.%La brazing material.Microstructural characterization was con-ducted using scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),etc.Analysis re-veals that progressive aggregation and precipitation of Cu-Sn intermetallic compounds occur with increasing Sn content,leading to microstructural coarsening.Notably,severe grain coarsening is observed when the Sn content reaches 4 wt.%.Shear testing of the BAg5CuZn-0.3 wt.%La-xSn brazing joints reveals a non-monotonic trend in joint strength:as Sn content increases,the shear strength initially improves but subsequently deteriorates after reaching an optimal value.
基金supported by the Major Science and Technology Project of Gansu Province(Grant No.22ZD6GA008)the National Natural Science Foundation of China(Nos.52261027,52001152 and 51961021)+2 种基金the Open Project of State Key Laboratory for Mechanical Behavior of Materials(20192102)Undergraduate Innovation and Entrepreneurship Training Program(Nos.DC20231482,DC20231188 and DC20231558)Gansu Provincial Excellent Graduate Students“Innovation Star”Program(2022CXZX-394)。
文摘The high-strength Mg-7Sn alloys(wt.%)with a heterogeneous grain structure were prepared by low-temperature extrusion(230°C)with the extrusion ratio of 9:1(9E230)and 17:1(17E230).The two extruded alloys contained fine dynamic recrystallization(DRX)grains(FG)and coarse un DRX grains(CG).The difference in deformability between CG and FG leads to the formation of heterogeneous grain structure.The average grain size and basal texture intensities increased while the volume fraction of CG decreased with increasing extrusion ratio.Tensile testing results indicated that the extruded 17E230 alloy exhibited higher tensile strengths than 9E230 alloy,whose tensile yield strength(σ_(0.2)),ultimate tensile strengths(σ_(b)),and elongation to failure(ε_(f))were 231.1 MPa,319.5MPa,and 12.54%respectively.The high tensile strengths of the extruded alloy mainly originated from grain refinement,texture strengthening,precipitation strengthening from a great number of nano-scale Mg_(2)Sn phases,solid solution strengthening and hetero-deformation induced(HDI)strengthening,while the good ductility of the alloy was also mainly attributed to grain refinement,activation of the non-basal slip systems and HDI hardening.
基金supported by the National Natural Science Foundation of China(No.51805265)the Fundamental Research Funds for the Central Universities,China(No.30922010921).
文摘Thin walls of an AZ91 magnesium alloy with fine equiaxed grains were fabricated via cold arc-based wire arc additive manufacturing(CA-WAAM),and the droplet transfer behaviours,microstructures,and mechanical properties were investigated.The results showed that the cold arc process reduced splashing at the moment of liquid bridge breakage and effectively shortened the droplet transfer period.The microstructures of the deposited samples exhibited layered characteristics with alternating distributions of coarse and fine grains.During layer-by-layer deposition,the β-phase precipitated and grew preferentially along grain boundaries,while the fineη-Al_(8)Mn_(5)phase was dispersed in the α-Mg matrix.The mechanical properties of the CA-WAAM deposited sample showed isotropic characteristics.The ultimate tensile strength and elongation in the building direction(BD)were 282.7 MPa and 14.2%,respectively.The microhardness values of the deposited parts were relatively uniform,with an average value of HV 69.6.
基金supported by the National Natural Science Foundation of China(Nos.52074246,22008224,52275390,52205429,52201146)National Defense Basic Scientific Research Program of China(Nos.JCKY2020408B002,WDZC2022-12)+2 种基金Key Research and Development Program of Shanxi Province(202102050201011,2022ZDYF035)Science and Technology Major Project of Shanxi Province(20191102008,20191102007)Guiding Local Science and Technology Development Projects by the Central Government(YDZJSX2022A025,YDZJSX2021A027).
文摘The regulation of sintering temperature in spark plasma sintering enables the achievement of grain refinement,phase control,and performance enhancement in the preparation of AZ91D magnesium alloy.This study investigates the influence of sintering temperature on microstructural evolution and mechanical properties of the AZ91D alloy.Microstructural analysis was conducted using scanning electron microscopy,electron backscatter diffraction,and X-ray diffraction.Microscopic structures and mechanical behaviors were examined through hardness and tensile tests.Elevated sintering temperatures resulted in reduced secondary phase content,leading to a decrease in mechanical performance.The alloy exhibited optimal mechanical properties at 320℃.The nanoparticle coarsening process and particle evolution during sintering were simulated using phase field methods.By optimizing the sintering temperature,precise control over microstructural and textural evolution can be achieved,facilitating the attainment of desired hardness levels and mechanical properties.
基金Outstanding Doctorate Dissertation Cultivation Fund of Xi'an University of Architecture and Technology(160842012)National Natural Science Foundation of China(52404409,52374401,52104382)+3 种基金China Postdoctoral Science Foundation(2024MD753961)Scientific and Technological Innovation Team Project of Shaanxi Innovation Capability Support Plan(2022TD-30)Key R&D Plan of Shaanxi Province(2023JBGS-14,2024QCYKXJ-116)Xi'an Science and Technology Plan Project(24ZDCYJSGG0043,2023JH-GXRC-0020)。
文摘Low-oxygen TZM alloy(oxygen content of 0.03vol%)was subjected to solid-solution heat treatment at various temperatures followed by quenching.Results show that the tensile strength of the alloy gradually decreases with the increase in solidsolution temperature,and the elongation first increases and then decreases.The the amount of nanoscale Ti-rich phases precipitated in low-oxygen TZM alloys gradually increases with the increase in solid-solution temperature.Special strip-shaped Ti-rich areas appear in the samples solidified at 1200 and 1300℃.The nanoscale Ti-rich phases ensure the uniform distribution of dislocations throughout TZM alloy,while significantly improving the plasticity of low-oxygen TZM alloy samples.
基金Major Scientific and Technological Project of Gansu(22ZD6GA008)Excellent Doctorate Project of Gansu(23JRRA806)National Natural Science Foundation of China(52175325,51961024,52071170)。
文摘The microstructure,micro-hardness,and tensile properties of interface between hot isostatic pressing densified low alloy steel and Inconel 690 cladding were investigated during the aging process at 600℃.The results show that the interface region can be divided into four zones from base metal to deposited metal:carbon-depleted zone(CDZ),partial melting zone(PMZ),planar growth zone(PGZ),and brownish feature zone(BFZ).Dimensions of these zones do not significantly change during aging.However,type I carbides noticeably increase in size in the PMZ,and precipitates clearly occur in the PGZ.The main reason for their growth and occurrence is continuous carbon migration.The highest micro-hardness appears in the PGZ and BFZ regions,which is related to carbon accumulation and precipitates in these regions.Tensile failure occurs on the base metal side due to the high strength mismatch between these two materials.The CDZ,composed of only ferrite,has lower strength and fractures at the boundary between CDZ and base metal.The ultimate tensile strength decreases by only 50 MPa after aging for 1500 h,and the interface region maintains high strength without significant deformation.
基金National Natural Science Foundation of China(12404230,52061027)Science and Technology Program Project of Gansu Province(22YF7GA155)+1 种基金Lanzhou Youth Science and Technology Talent Innovation Project(2023-QN-91)Zhejiang Provincial Natural Science Foundation of China(LY23E010002)。
文摘(TiZrHf)_(50)Ni_(30)Cu_(20-x)Co_(x)(x=2,4,6,at%)high-entropy high-temperature shape memory alloys were fabricated by watercooled copper crucible in a magnetic levitation vacuum melting furnace,and the effects of Co content on microstructure and mechanical properties were investigated.The results indicate that the grain size of the alloy decreases with increasing the Co content.In the as-cast state,the alloy consists primarily of the B19′phase,with a trace of B2 phase.The fracture morphology is predominantly composed of the B19′phase,whereas the B2 phase is nearly absent.Increasing the Co content or reducing the sample dimensions(d)markedly enhance the compressive strength and ductility of the alloy.When d=2 mm,the(TiZrHf)_(50)Ni_(30)Cu_(14)Co_(6) alloy demonstrates the optimal mechanical properties,achieving a compressive strength of 2142.39±1.8 MPa and a plasticity of 17.31±0.3%.The compressive cyclic test shows that with increasing the compressive strain,the residual strain of the(TiZrHf)_(50)Ni_(30)Cu_(14)Co_(6) alloy increases while the recovery ability declines.The superelastic recovery capability of the alloy is continuously enhanced.The superelastic recovery rate increases from 1.36%to 2.12%,the residual strain rate rises from 1.79%to 5.52%,the elastic recovery rate ascends from 3.86%to 7.36%,while the total recovery rate declines from 74.48%to 63.20%.
基金National Natural Science Foundation of China(52075449,5197052086)。
文摘The transient liquid-phase(TLP)diffusion bonding of GH5188 with a BNi-5 interlayer was focused on.Parameters were chosen and optimized for GH5188 alloy according to the TLP joining mechanism.The microstructure evolution and mechanical properties of the joints were studied.Results show that the relatively complete isothermal solidification zone(ISZ)ensures a reliable connection of the base metal(BM).Within the temperature range of 1110–1190°C,higher bonding temperatures can widen ISZ and promote joint composition homogenization,thus improving mechanical properties.However,the increase in precipitated phase has an adverse effect on the mechanical properties of the joint.The maximum shear strength,reaching 482 MPa,is achieved at 1130°C,representing 84.6%of BM strength.Within the pressure range of 5–15 MPa,both precipitated phases in adiabatic solidification zone(ASZ)and voids generated by partial melting increase.On the contrary,their sizes decrease significantly under higher bonding pressure,resulting in an upward trend in alloy mechanical properties.The maximum shear strength of 490 MPa is attained at a bonding pressure of 15 MPa.The joint exhibits a typical mixed fracture pattern,with the small brittle M_(23)C_(6) phase and voids significantly impacting mechanical properties.Nano-indentation tests indicate that ASZ is a potential source of cracks.
基金Major Science and Technology Project of Gansu Province(22ZD6GA008)National Natural Science Foundation of China(52261027,51961021,52001152)+2 种基金Open Project of State Key Laboratory for Mechanical Behavior of Materials(20192102)Undergraduate Innovation and Entrepreneurship Training Program(DC20231188,DC20231482,DC20231558,DC20231469,DC20231441)Supported by Sinoma Institute of Materials Research(Guang Zhou)Co.,Ltd(SIMR)。
文摘The effects of the co-addition of Ni and Zn on the microstructure and mechanical properties of the extruded Mg-6.84Y2.45Cu(MYC,wt%)alloy were researched.Results show that the as-cast Mg-6.79Y-1.21Cu-1.12Ni-1.25Zn(MYCNZ,wt%)alloy consists of theα-Mg,a few Y-rich phases,lamellar 18R-long period stacking ordered(LPSO)phase,and granular Mg_(2)(Cu,Ni,Zn)phase.After the homogenization process,phase transformation occurs in MYCNZ alloy.Some 18R-LPSO phases at the grain boundary are transformed into the thin striped 14H-LPSO phase in the grains.After extrusion,the amount,morphology,and distribution of the second phase are changed,and the grain size of the extruded MYCNZ alloy is significantly reduced to approximately 2.62µm.Additionally,a weaker basal texture is formed in the extruded MYCNZ alloy.The tensile results indicate that the co-addition of Ni and Zn significantly enhances the tensile strength of the extruded MYC alloy while maintaining good ductility.The tensile yield strength(σ_(0.2)),ultimate tensile strength(σ_(b)),and elongation to failure(ε_(L))of the extruded MYCNZ alloy are 266.9 MPa,299.8 MPa,and 20.1%,respectively.This alloy has a good strength-plastic synergistic effect.The excellent tensile strength of the extruded MYCNZ alloy at room temperature is mainly due to grain refinement and the second phase strengthening effect,and its outstanding ductility is ascribed to the texture weakening and activation of non-basal slips.
基金National Natural Science Foundation of China(52275308,52301146)Fundamental Research Funds for the Central Universities(2023JG007)Supported by Shi Changxu Innovation Center for Advanced Materials(SCXKFJJ202207)。
文摘AZ31/Al/Ta composites were prepared using the vacuum hot compression bonding(VHCB)method.The effect of hot compressing temperature on the interface microstructure evolution,phase constitution,and shear strength at the interface was investigated.Moreover,the interface bonding mechanisms of the AZ31/Al/Ta composites during the VHCB process were explored.The results demonstrate that as the VHCB temperature increases,the phase composition of the interface between Mg and Al changes from the Mg-Al brittle intermetallic compounds(Al_(12)Mg_(17)and Al_(3)Mg_(2))to the Al-Mg solid solution.Meanwhile,the width of the Al/Ta interface diffusion layer at 450℃increases compared to that at 400℃.The shear strengths are 24 and 46 MPa at 400 and 450℃,respectively.The interfacial bonding mechanism of AZ31/Al/Ta composites involves the coexistence of diffusion and mechanical meshing.Avoiding the formation of brittle phases at the interface can significantly improve interfacial bonding strength.
基金financially supported by the Fundamental Research Program of the Korea Institute of Materials Science(Grant No.360–05–04-PNKA540)the National Research Foundation of Korea(CRC23011–210).
文摘The microstructure and texture evolution of Mg-xAl-1Zn-1Y-0.1Mn alloys are systematically analyzed.There is no effect of Al addition on grain refinement in the Mg-1Zn-1Y-0.1Mn alloy,but the addition of 0.5 wt.%or more Al element dramatically changes texture from a weak texture to a strong basal texture.The predominant second phase particle of Mg_(3)Zn_(3)Y_(2) phase in the Mg-1Zn-1Y-0.1Mn alloy changes to Al_(2)Y phase by the addition of only 0.1 wt.%Al element,and the concentrations of dissolved Y element in the 0Al,0.1Al,0.3Al,0.5Al and 1Al alloys are 0.50,0.31,0.23,0.15 and 0.06 wt.%,respectively.Although the 0.5 wt.%or more Al-added alloys have higher Schmid factor for prismatic(a)slip than the 0.3 wt.%or less Al-added alloys,the lower Al containing alloys show much higher activity of prismatic (a)slip than the higher Al containing alloys.It demonstrates that the addition of high amount of Al element in Mg-Zn-RE alloy dramatically decrease the dissolved Y element,resulting in a significant deterioration of activity of prismaticslip and consequently a poor formability at room temperature.
基金financial support by the National Natural Science Foundation of China(No.52474361)the Independent Research Project of State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratory of Advanced Ferrometallurgy,Shanghai University(No.SKLASS 2023-Z01)the Science and Technology Commission of Shanghai Municipality(No.19DZ2270200).
文摘The fracture mechanisms of coarse-grained heat-affected zone(CGHAZ)for Mg and Mg–Ca deoxidized high-strength low-alloy(HSLA)steels after high heat input welding(HHIW)were investigated based on the microstructures,crack behaviors and mechanical properties.Compared to Mg–Ca steel,the proportion of intergranular acicular ferrites(IAFs)and polygonal ferrites(PFs)in Mg steel increases from 59.97%to 90.16%.The high-angle grain boundaries(HAGBs)and geometrically necessary dislocations density increase from 55.5%and 4.30×10^(14) m^(-2)to 70.4%and 5.48×10^(14) m^(–2),respectively,while effective grain size decreases from 9.46 to 8.12μm.The area fraction of radial zone in Mg steel decreases from 80.8%to 37.7%and cleavage plane is smaller with more curved and finer tearing ridges.The inclusions distributed at the center of cleavage planes and along river lines can serve as crack initiation sites.The zigzag pattern of primary crack propagation path has width of 476μm and the length of secondary cracks remains below 10μm.These cracks are deflected or arrested by IAFs,PFs and HAGBs,and tend to propagate along{110}plane family.These factors contribute to superior overall mechanical properties of Mg steel,especially increasing low-temperature impact toughness from 23 to 175 J.
基金Chongqing Natural Science Foundation(No.CSTB2022NSCQ-MSX1394)Graduate Research and Innovation Foundation of Chongqing,China(Grant No.CYS22008)+2 种基金Open Project of State Key Laboratory of Advanced Special Steel,Shanghai Key Laboratory of Advanced Ferrometallurgy,Shanghai University(SKLASS 2023-10)the Science and Technology Commission of Shanghai Municipality(No.19DZ2270200)the Open Project of the Large Casting and Forging Manufacturing Technology Engineering Center of Shanghai Institute of Mechanical and Electrical Engineering,State Key Laboratory of Vanadium and Titanium Resources Open Fund(No.2022P4FZG04A).
文摘The microstructure evolution and mechanical properties of a Fe-0.12C-0.2Si-1.6Mn-0.3Cr-0.0025B(wt.%)steel with different initial microstructures,i.e.,hot rolled(HR)and cold rolled-annealed(CRA),were studied through optical microscopy,scanning electron microscopy,electron channeling contrast imaging,microhardness and room temperature uniaxial tensile tests.After water quenching from 930℃ to room temperature,a fully martensitic microstructure was obtained in both as-quenched HR and CRA specimens,which shows a microhardness of 480±5 HV,and no significant difference in microstructure and microhardness was observed.Tensile test results show that the product of tensile strength and total elongation(UTS×TE)of the as-quenched HR specimen,i.e.,24.1 GPa%,is higher than that of the as-quenched CRA specimen,i.e.,18.9 GPa%.While,after being tempered at 300℃,the martensitic microstructures and mechanical properties of the two as-quenched specimens change significantly due to the synergy role of the matrix phase softening and the precipitation strengthening.Concerning the maximum UTS×TE,it is 18.9 GPa%obtained in the as-quenched CRA one,while that is 24.4 GPa%obtained in the HR specimen after tempered at 300℃ for 5 min.
基金supported by the National Natural Science Foundation of China(Nos.51971021,52203382,and 11775017)the National Magnetic Confinement Fusion Program of China(No.2019YFE03130002)the Young Talent Fund of Association for Science and Technology in Shaanxi,China(No.20230415).
文摘The TiNbV_(0.5)Ta_(0.5)Cr_(x)(x=0,0.1,0.2,0.5)refractory high-entropy alloys(RHEAs)with an excellent combination of ductility and strength were designed and prepared for high-temperature applications.The yield strength,ultimate tensile strength,and elongation of the TiNbV_(0.5)Ta_(0.5)Cr_(0.1) alloy were 878 MPa,928 MPa,and 21.6%,respectively.Important issues of microstructure evolution,precipitation process,and their impact on mechanical properties were concerned.Then,the effect of Cr content on the mechanical properties of TiNbV_(0.5)Ta_(0.5)Cr_(x) alloys was evaluated through a quantitative analysis of the strengthening mechanism,which elucidated the trade-offrelationship between solid solution strengthening and precipitation strengthening in RHEA.The microstructure evolution of the TiNbV_(0.5)Ta_(0.5)Cr_(x) alloys involved the formation and interconversion of titanium allotropes(α-Ti and β-Ti)and the precipitation of the Laves phase.Significant embrittlement was induced by the preferential precipitation of α-Ti on the grain boundary.The TiNbV_(0.5)Ta_(0.5)Cr_(x) alloys exhibited an incubation period for Laves phase precipitation,which was related to the Cr content in the alloy.The Laves phase preferentially nucleated next to α-Ti due to the redistribution of elements during the α-Ti precipitation process.The precipitation of the Laves phase played an important role in enhancing the strength of the TiNbV_(0.5)Ta_(0.5)Cr_(x) alloys.
