The microstructures and hot tensile behaviors of ZK30 alloys subjected to single-and multi-pass friction stir processing(FSP)were systematically investigated.Following single-pass FSP(S-FSP),coarse grains underwent re...The microstructures and hot tensile behaviors of ZK30 alloys subjected to single-and multi-pass friction stir processing(FSP)were systematically investigated.Following single-pass FSP(S-FSP),coarse grains underwent refinement to 1−2μm,with a distinct basal texture emerging in the stir zone(SZ).Additionally,second-phase particles were fragmented,dispersed,and partially dissolved.Multi-pass FSP(M-FSP)further enhanced the homogeneity of the microstructure,reduced texture intensity differences,and decreased the fraction of second-phase particles by 50%.Both S-FSP and M-FSP SZs demonstrated superplasticity at strain rates below 1×10^(−3)s^(−1)and at temperatures of 250−350℃.The S-FSP SZ exhibited an elongation of 390%at 250℃and 1×10^(−4)s^(−1),while the M-FSP SZ achieved an elongation of 406%at 350℃and 1×10^(−3)s^(−1).The superplastic deformation of SZ was co-dominated by grain boundary sliding(GBS)and the solute-drag mechanism in S-FSP and mainly by GBS in M-FSP.展开更多
The influence of overlap multi-pass friction stir processing on the microstructure and the mechanical properties, in particular, strength, ductility and hardness of die cast A1-7Si-3Cu aluminum alloy was investigated....The influence of overlap multi-pass friction stir processing on the microstructure and the mechanical properties, in particular, strength, ductility and hardness of die cast A1-7Si-3Cu aluminum alloy was investigated. It was observed that increase in the number of overlap passes friction stir processing resulted in significant refinement and redistribution of aluminum silicon eutectic phase and elimination of casting porosities. The microstructural refinement by the friction stir processing not only increases the ultimate tensile strength from 121 to 273 MPa, but also increases the ductility as observed by the increase in fracture strain from 1.8% to 10%. Analysis of the fractured surface reveals that the microstructural refinement obtained by friction stir processing plays a vital role in transforming the fracture mode from completely mixed mode to the ductile mode of the fracture with increasing number of passes. The change in the size, shape, morphology and distribution of eutectic silicon particles and elimination of the porosities are the main reasons for the increases in tensile strength and ductility due to friction stir processing.展开更多
Three-pass friction stir processing(FSP)with different moving distances of the stirring tool between the two successivepasses,50%diameter of the pin(traditional way)and50%diameter of the shoulder(novel way),was conduc...Three-pass friction stir processing(FSP)with different moving distances of the stirring tool between the two successivepasses,50%diameter of the pin(traditional way)and50%diameter of the shoulder(novel way),was conducted on7B04-O Al alloy.The result shows that an improvement in the mechanical properties of the processed zone is accomplished due to grain and secondphase particles refinement.The hardness of the multi-pass FSP(M-FSP)sample is about HV40higher than that of the base metal.And the tensile strength of the M-FSP specimens is also significantly increased to about1.4times that of the base metal.Besides,theweak region of the processed zone is mainly dependent on the moving distance,where it is the previous pass stir zone in thetraditional way and the transitional zone in the novel way.Increasing the rotational speed narrows the weak region in the novel way,while it does not in the traditional way.展开更多
A large-scale fine-grained Mg-Gd-Y-Zn-Zr alloy plate with high strength and ductility was successfully prepared by multi-pass friction stir processing(MFSP)technology in this work.The structure of grains and long peri...A large-scale fine-grained Mg-Gd-Y-Zn-Zr alloy plate with high strength and ductility was successfully prepared by multi-pass friction stir processing(MFSP)technology in this work.The structure of grains and long period stacking ordered(LPSO)phase were characterized,and the mechanical properties uniformity was investigated.Moreover,a quantitative relationship between the microstructure and tensile yield strength was established.The results showed that the grains in the processed zone(PZ)and interfacial zone(IZ)were refined from 50μm to 3μm and 4μm,respectively,and numerous original LPSO phases were broken.In IZ,some block-shaped 18R LPSO phases were transformed into needle-like 14H LPSO phases due to stacking faults and the short-range diffusion of solute atoms.The severe shear deformation in the form of kinetic energy caused profuse stacking fault to be generated and move rapidly,greatly increasing the transformation rate of LPSO phase.After MFSP,the ultimate tensile strength,yield strength and elongation to failure of the large-scale plate were 367 MPa,305 MPa and 18.0% respectively.Grain refinement and LPSO phase strengthening were the major strengthening mechanisms for the MFSP sample.In particularly,the strength of IZ was comparable to that of PZ because the strength contribution of the 14H LPSO phase offsets the lack of grain refinement strengthening in IZ.This result opposes the widely accepted notion that IZ is a weak region in MFSP-prepared large-scale fine-grained plate.展开更多
The effect of multi-pass friction stir processing(FSP)on the tribological properties of conventionally-cast Al−8.5Fe−1.3V−1.7Si(FVS0812)alloy was investigated.The pin-on-disk dry sliding wear tests were conducted at r...The effect of multi-pass friction stir processing(FSP)on the tribological properties of conventionally-cast Al−8.5Fe−1.3V−1.7Si(FVS0812)alloy was investigated.The pin-on-disk dry sliding wear tests were conducted at room temperature under the applied pressures of 0.25,0.50,and 0.75 MPa.The results showed that FSP substantially refined and improved the distribution of coarse¸-Al_(13)Fe4 platelets andα-Al_(12)(Fe,V)_(3)Si intermetallics in the microstructure of alloys and eliminated the intermetallic-related defects.Consequently,the mechanical properties of the alloys,especially their ductility,were improved,which enhanced the stability of the protective tribolayer formed on their worn surfaces.According to the wear test results,the FSPed samples showed improved tribological properties especially at the higher applied pressures.For instance,at the applied pressure of 0.75 MPa,the wear rate and average friction coefficient of four-pass FSPed sample were lower than those of the base as-cast sample by 97%and 52%,respectively.SEM examination of the worn surfaces and wear debris also demonstrated that the wear mechanism changed from severe delamination/abrasion and microcracking of the tribolayer in the as-cast samples to mild delamination/abrasion and minor plastic wear in the FSPed samples.展开更多
Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing addit...Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.展开更多
High entropy alloys(HEAs)have recently attracted significant attention due to their exceptional mechanical properties and potential applications across various fields.Friction stir welding and processing(FSW/P),as not...High entropy alloys(HEAs)have recently attracted significant attention due to their exceptional mechanical properties and potential applications across various fields.Friction stir welding and processing(FSW/P),as notable solid-state welding and processing techniques,have been proved effectiveness in enhancing microstructures and mechanical properties of HEAs.This review article summarizes the current status of FSW/P of HEAs.The welding materials and conditions used for FSW/P in HEAs are reviewed and discussed.The effects of FSW/P on the evolutions of grain structure,texture,dislocation,and secondary phase for different HEAs are highlighted.Furthermore,the influences of FSW/P on the mechanical properties of various HEAs are analyzed.Finally,potential applications,challenges,and future directions of FSW/P in HEAs are forecasted.Overall,FSW/P enable to refine grains of HEAs through dynamic recrystallization and to activate diverse deformation mechanisms of HEAs through tailoring phase structures,thereby significantly improving the strength,hardness,and ductility of both single-and dual-phase HEAs.Future progress in this field will rely on comprehensive optimization of processing parameters and alloy composition,integration of multi-scale modeling with advanced characterization for in-depth exploration of microstructural mechanisms,systematic evaluation of functional properties,and effective bridging of the gap between laboratory research and industrial application.The review aims to provide an overview of recent advancements in the FSW/P of HEAs and encourage further research in this area.展开更多
A large-scale Mg-6Al-Zn plate was prepared by multi-pass submerged friction stir processing(M-SFSP)and its superplastic deformation behavior was investigated.The maximum elongation of 467%,332%and 421%was attained for...A large-scale Mg-6Al-Zn plate was prepared by multi-pass submerged friction stir processing(M-SFSP)and its superplastic deformation behavior was investigated.The maximum elongation of 467%,332%and 421%was attained for the samples oriented in the processing direction(PD),45°tilted toward the PD,and transverse direction(TD),respectively,when deformed at 623 K and a strain rate of 1×10^(−3) s^(−1).This was attributed to the homogeneous and fine-grained structure with mostly high-angle grain boundaries facilitating the prevalent deformation mechanism of grain boundary sliding,along with the weakened texture and dynamic recrystallization during hot deformation.展开更多
Interlayer friction stir processing(FSP)has been proved to be an efective method of enhancing the mechanical properties of wire arc-directed energy deposited(WA-DED)samples.However,the original deposition structure wa...Interlayer friction stir processing(FSP)has been proved to be an efective method of enhancing the mechanical properties of wire arc-directed energy deposited(WA-DED)samples.However,the original deposition structure was still retained in the FSP-WA-DED component besides the processed zone(PZ),thus forming a composite structure.Considering the material utilization and practical service process of the deposited component,more attention should be paid on this special composite structure,but the relevant investigation has not been carried out.In this study,an Al–Mg–Sc alloy was prepared by WA-DED with interlayer FSP treatment,and the composite structure was frstly investigated.Almost all of the pores were eliminated under the pressure efect from the tool shoulder.The grains were further refned with an average size of about 1.2μm in the PZ.Though no severe plastic deformation was involved in the retained WA-DED deposition zone,comparable tensile properties with the PZ sample were obtained in the composite structure.Low ultimate tensile strength(UTS)of 289 MPa and elongation of 3.2%were achieved in the WA-DED sample.After interlayer FSP treatment,the UTS and elongation of the PZ samples were signifcantly increased to 443 MPa and 16.3%,while those in the composite structure remained at relatively high levels of 410 MPa and 13.5%,respectively.Meanwhile,a high fatigue strength of 180 and 130 MPa was obtained in the PZ and composite structure samples,which was clearly higher than that of the WA-DED sample(100 MPa).It is concluded that the defects in traditional WA-DED process can be eliminated in the composite structure after interlayer FSP treatment,resulting in enhanced tensile and fatigue properties,which provides an efective method of improving the mechanical properties of the WA-DED sample.展开更多
Ti-10V-2Fe-3Al alloy with fine-grainedβphases was fabricated by friction stir processing with opti-mized processing parameters.The superplastic behavior of the specimens was investigated by tensile deformation at dif...Ti-10V-2Fe-3Al alloy with fine-grainedβphases was fabricated by friction stir processing with opti-mized processing parameters.The superplastic behavior of the specimens was investigated by tensile deformation at different strain rates and temperatures,and an optimal superplastic elongation of 634%was achieved at 700℃ and 3×10^(-4)/s.An annealing treatment at 650℃ for 60 min showed a mi-crostructure withαprecipitates distributed in theβmatrix in the friction stir specimen.Such pre-heat treatment improves the superplasticity of the specimen,achieving an elongation of up to 807%at 750℃ and 3×10^(-4)/s.The influences of tensile temperatures and strain rates on the microstructural evolution,such as grain size variation,grain morphology,and phase transformations,were discussed.The super-plastic deformation behavior of fine-grained Ti-10V-2Fe-3Al alloy is controlled by grain boundary sliding and accompanied by dynamic phase transformation and recrystallization.展开更多
Bio-magnesium(Mg)alloys exhibit excellent biocompatibility and biodegradability,making them highly promising for implant applications.However,their limited strength-ductility balance remains a critical challenge restr...Bio-magnesium(Mg)alloys exhibit excellent biocompatibility and biodegradability,making them highly promising for implant applications.However,their limited strength-ductility balance remains a critical challenge restricting widespread use.In this study,ultra-fine-grained and homogeneous Mg alloys were fabricated using double-sided friction stir processing(DS-FSP)with liquid CO_(2) rapid cooling,leading to a significant enhancement in the strength-ductility synergy of the stirred zone.The results demonstrate that DS-FSP samples exhibit simultaneous improvements in ultimate tensile strength(UTS)and elongation,reaching 334.1±15 MPa and 28.2±7.3%,respectively.Compared to the non-uniform fine-grained microstructure obtained through single-sided friction stir processing,DS-FSP generates a uniform ultra-fine-grained structure,fundamentally altering the fracture behavior and mechanisms of Mg alloys.The DS-FSP samples exhibit irregular fracture patterns due to variations in basal slip system activation among different grains.In contrast,single-sided friction stir processing samples,characterized by a fine-grained yet heterogeneous microstructure,display flat shear fractures dominated by high-density dislocation initiation induced by twin formation,with fracture propagation dictated by the non-uniform texture.By achieving an ultra-fine grain size and homogeneous texture,DS-FSP effectively modifies the fracture mechanisms,thereby enhancing the strength-ductility balance of bio-magnesium alloys.展开更多
To promote early rapid osteogenesis and prevent late implant-related infection,it is critical to develop ef-fective and reliable surface treatment technologies for enhancing both osteogenic and antibacterial prop-erti...To promote early rapid osteogenesis and prevent late implant-related infection,it is critical to develop ef-fective and reliable surface treatment technologies for enhancing both osteogenic and antibacterial prop-erties of titanium alloy implants.Reduced graphene oxide(rGO)is considered a promising modification candidate.However,whether rGO retains its osteogenic and antibacterial functions after being applied to modify titanium alloy surfaces depends on the surface treatment technology employed.In this study,rGO was integrated onto the surface of Ti-35Nb-2Ta-3Zr(TNTZ)alloy through friction stir processing(FSP),yielding a consolidated TNTZ/F-rGO composite.The incorporation of rGO not only significantly im-proved the microhardness and hydrophilicity of the material,but also exhibited positive biological effects in vitro experiments:it effectively promoted the proliferation,osteogenic differentiation,alkaline phos-phatase(ALP)production and extracellular matrix mineralization of BMSCs.Furthermore,TNTZ/F-rGO ex-hibited potent antibacterial activity via surface-contact mechanisms.In summary,the rGO-modified in-tegrated titanium alloy has excellent osteogenic properties and high-efficiency antibacterial ability.This study provides new insights and strategies for the design of graphene-based biomaterials and implant surface modification technologies.展开更多
The inherent trade-off between ductility and strength in Mg alloys remains a significant challenge,primarily governed by microstructural distribution and texture characteristics.Friction stir processing(FSP),a severe ...The inherent trade-off between ductility and strength in Mg alloys remains a significant challenge,primarily governed by microstructural distribution and texture characteristics.Friction stir processing(FSP),a severe plastic deformation(SPD)technique,refines microstructures by generating fine grains,uniformly dispersed fragmented particles,and a high fraction of high-angle grain boundaries(HAGBs),thereby facilitating superplastic forming at high strain rates and low temperatures.In the present work,a dual eccentric-pin tool(DEPT)FSP was employed to incorporate ZrO_(2) particles into a 6 mm thick AZ91D Mg alloy,leading to the formation of high volume{10-12}twins,dislocations,and β-Mg_(17)Al_(12) precipitates within the stirred zone.The microstructural evolution and mechanical behaviour of the stir zone under various process parameters were analysed using scanning electron microscopy(SEM),X-ray diffraction(XRD),electron backscatter diffraction(EBSD),and transmission electron microscopy(TEM).The DEPT enhanced plastic shearing and dynamic recrystallization,significantly reducing the grain size from 15.6μm to 2.35μm while promoting uniform dislocation distribution within the stir zone(SZ).Grain orientation analysis revealed a transition from basal to prismatic texture dominance(29.3% volume fraction)due to intensified radial-tangential coupling shear deformation,facilitating the activation of non-basal slip systems.The DEPT evidently improved the hardness of the SZ from 58 to 92 HV and increased tensile strength from 234 MPa to 325 MPa while maintaining an elongation of 23.8%,achieving an optimal strengthductility balance.This work presents a one-step approach for tailoring microstructural heterogeneity and enhancing mechanical properties in AZ91D/ZrO_(2) composites using the DEPT FSP technique.The method provides an effective strategy for mitigating the strength-ductility trade-off commonly observed in Mg alloys.展开更多
A novel Mg_(98.5)Zn_(0.5)Y alloy sheet with ultrafine grains and exceptional electromagnetic shielding performance has been fabricated using friction stir processing(FSP).This study investigates the impact of FSP on t...A novel Mg_(98.5)Zn_(0.5)Y alloy sheet with ultrafine grains and exceptional electromagnetic shielding performance has been fabricated using friction stir processing(FSP).This study investigates the impact of FSP on the microstructure,mechanical properties,and electromagnetic interference(EMI)shielding effectiveness(SE)of the alloy,specifically across three distinct layers within the stir zone(SZ):Top,Middle,and Bottom.The results reveal that the Mg_(12)YZn long-period stacking ordered(LPSO)phase is the predominant structure,undergoing significant grain refinement.The grain size is drastically reduced from 1.5 mm in the as-cast state to 12.6μm,10.0μm,and 7.1μm in the Top,Middle,and Bottom,respectively.This grain refinement and fragmentation of the LPSO phase into nanoscale particles result in a substantial enhancement of mechanical properties.The ultimate tensile strength(UTS)reached 358.2 MPa with an elongation(EL)of 15.1%,reflecting a 344% increase in strength and a 733% improvement in ductility compared to the as-cast material.Simultaneously,the EMI SE was maintained between 70 and 110.4 dB over a broad frequency range(30-4500 MHz).Despite the nanoscale LPSO particles contributing minimally to EMI shielding,the lamellar LPSO structure demonstrated excellent performance through multiple electromagnetic wave reflections within the matrix.These findings underscore the dual benefits of FSP in improving both mechanical strength and electromagnetic shielding effectiveness,positioning this Mg_(98.5)Zn_(0.5)Y alloy for advanced applications in the electronics and telecommunications sectors.展开更多
Microstructure and tensile behaviors of AZ31 magnesium alloy prepared by friction stir processing（FSP） were investigated.The results show that microstructure of the AZ31 hot-rolled plate with an average grain size o...Microstructure and tensile behaviors of AZ31 magnesium alloy prepared by friction stir processing（FSP） were investigated.The results show that microstructure of the AZ31 hot-rolled plate with an average grain size of 92.0 μm is refined to 11.4 μm after FSP.The FSP AZ31 alloy exhibits excellent plasticity at elevated temperature,with an elongation to failure of 1050% at 723 K and a strain rate of 5×10-4 s-1.The elongation of the FSP material is 268% at 723 K and 1×10-2 s-1,indicating that high strain rate superplasticity could be achieved.On the other hand,the hot-rolled base material,which has a coarse grain structure,possesses no superplasticity under the experimental conditions.展开更多
The ultra-fine structured Ni?Al?WC layer with interlocking bonding was fabricated on austenitic stainless steel by combination of laser clad and friction stir processing (FSP). Laser was initially applied to Ni?Al ele...The ultra-fine structured Ni?Al?WC layer with interlocking bonding was fabricated on austenitic stainless steel by combination of laser clad and friction stir processing (FSP). Laser was initially applied to Ni?Al elemental powder preplaced on the austenitic stainless steel substrate to produce a coating for further processing. The as-received coating was subjected to FSP treatment, processed by a rotary tool rod made of WC?Co alloy, to obtain sample for inspection. Microstructure, phase constitutions, hardness and wear property were investigated by methods of scanning electronic microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX) microanalysis, and X-ray diffraction (XRD), hardness test alongside with dry sliding wear test. The results show that the severe deformation effect exerted on the specimen resulted in an ultra-fine grain layer of about 100μmin thickness and grain size of 1?2μm. Synergy between introduction of WC particles to the deformation layer and deformation strengthening contributes greatly to the increase in hardness and friction resistance. An interlocking bonding between the coating and matrix which significantly improves bonding strength was formed due to the severe deformation effect.展开更多
The effects of friction stir processing （FSP） on the microstructure, microtexture and hardness of rolled pure aluminum were investigated. The microstructure and microtexture were characterized using electron backsca...The effects of friction stir processing （FSP） on the microstructure, microtexture and hardness of rolled pure aluminum were investigated. The microstructure and microtexture were characterized using electron backscattered diffraction （EBSD） technique on the transversal section. The stir zone （SZ） contains fine, equiaxed and fully recrystallized grains. The texture component of the base material mainly consists of R, S and brass R textures. Miner copper texture component is also determined. In the center of the stir zone, the dominant texture is （111） parallel to about 70° from ND pointing toward RD. The textures of this location rotating clockwise about 30° and anticlockwise about 60° around the ND result in the textures of the areas, which are 3 mm apart from this location on the retreating side and advancing side, respectively.展开更多
Magnesium(Mg)alloys have been extensively used in various fields,such as aerospace,automobile,electronics,and biomedical industries,due to their high specific strength and stiff ness,excellent vibration absorption,ele...Magnesium(Mg)alloys have been extensively used in various fields,such as aerospace,automobile,electronics,and biomedical industries,due to their high specific strength and stiff ness,excellent vibration absorption,electromagnetic shielding eff ect,good machinability,and recyclability.Friction stir processing(FSP)is a severe plastic deformation technique,based on the principle of friction stir welding.In addition to introducing the basic principle and advantages of FSP,this paper reviews the studies of FSP in the modification of the cast structure,superplastic deformation behavior,preparation of finegrained Mg alloys and Mg-based surface composites,and additive manufacturing.FSP not only refines,homogenizes,and densifies the microstructure,but also eliminates the cast microstructure defects,breaks up the brittle and network-like phases,and prepares fine-grained,ultrafine-,and nano-grained Mg alloys.Indeed,FSP significantly improves the comprehensive mechanical properties of the alloys and achieves low-temperature and/or high strain rate superplasticity.Furthermore,FSP can produce particle-and fiber-reinforced Mg-based surface composites.As a promising additive manufacturing technique of light metals,FSP enables the additive manufacturing of Mg alloys.Finally,we prospect the future research direction and application with friction stir processed Mg alloys.展开更多
A route combining powder metallurgy and subsequent friction stir processing was utilized to fabricate carbon nanotube （CNT） reinforced AI （CNT/AI） and 6061AI （CNT/6061AI） composites. Microstructural observations...A route combining powder metallurgy and subsequent friction stir processing was utilized to fabricate carbon nanotube （CNT） reinforced AI （CNT/AI） and 6061AI （CNT/6061AI） composites. Microstructural observations indicated that CNTs were uniformly dispersed in the matrix in both CNT/AI and CNT/6061AI composites. Mg and Si elements tended to segregate at CNT-AI interfaces in the CNT/6061AI composite during artificial aging treatment. The tensile properties of both the AI and 6061AI were increased by CNT incorporation. The electrical conductivity of CNT/AI was decreased by CNT addition, while CNT/6061AI exhibited an increase in electrical conductivity due to the Mg and Si segregation.展开更多
基金supported by Hebei Natural Science Foundation,China (No.E2020203158)Hebei Provincial Department of Human Resources and Social Security,China (No.E2020100006)。
文摘The microstructures and hot tensile behaviors of ZK30 alloys subjected to single-and multi-pass friction stir processing(FSP)were systematically investigated.Following single-pass FSP(S-FSP),coarse grains underwent refinement to 1−2μm,with a distinct basal texture emerging in the stir zone(SZ).Additionally,second-phase particles were fragmented,dispersed,and partially dissolved.Multi-pass FSP(M-FSP)further enhanced the homogeneity of the microstructure,reduced texture intensity differences,and decreased the fraction of second-phase particles by 50%.Both S-FSP and M-FSP SZs demonstrated superplasticity at strain rates below 1×10^(−3)s^(−1)and at temperatures of 250−350℃.The S-FSP SZ exhibited an elongation of 390%at 250℃and 1×10^(−4)s^(−1),while the M-FSP SZ achieved an elongation of 406%at 350℃and 1×10^(−3)s^(−1).The superplastic deformation of SZ was co-dominated by grain boundary sliding(GBS)and the solute-drag mechanism in S-FSP and mainly by GBS in M-FSP.
文摘The influence of overlap multi-pass friction stir processing on the microstructure and the mechanical properties, in particular, strength, ductility and hardness of die cast A1-7Si-3Cu aluminum alloy was investigated. It was observed that increase in the number of overlap passes friction stir processing resulted in significant refinement and redistribution of aluminum silicon eutectic phase and elimination of casting porosities. The microstructural refinement by the friction stir processing not only increases the ultimate tensile strength from 121 to 273 MPa, but also increases the ductility as observed by the increase in fracture strain from 1.8% to 10%. Analysis of the fractured surface reveals that the microstructural refinement obtained by friction stir processing plays a vital role in transforming the fracture mode from completely mixed mode to the ductile mode of the fracture with increasing number of passes. The change in the size, shape, morphology and distribution of eutectic silicon particles and elimination of the porosities are the main reasons for the increases in tensile strength and ductility due to friction stir processing.
基金support received from the Ministry of Education and Science,Russia,(Belgorod State University project No.1533)is acknowledgedsupport from the National Science Foundation for Young Scientists of China(No.51501035)+1 种基金Chinese Postdoctoral Science Foundation(No.2016T90227)supported financially by the National Natural Science Foundation of China(No.51334006)
文摘Three-pass friction stir processing(FSP)with different moving distances of the stirring tool between the two successivepasses,50%diameter of the pin(traditional way)and50%diameter of the shoulder(novel way),was conducted on7B04-O Al alloy.The result shows that an improvement in the mechanical properties of the processed zone is accomplished due to grain and secondphase particles refinement.The hardness of the multi-pass FSP(M-FSP)sample is about HV40higher than that of the base metal.And the tensile strength of the M-FSP specimens is also significantly increased to about1.4times that of the base metal.Besides,theweak region of the processed zone is mainly dependent on the moving distance,where it is the previous pass stir zone in thetraditional way and the transitional zone in the novel way.Increasing the rotational speed narrows the weak region in the novel way,while it does not in the traditional way.
基金supported by the National Key Research and Development Program of China(2021YFB3501002)State Key Program of National Natural Science Foundation of China(5203405)+3 种基金National Natural Science Foundation of China(51974220,52104383)National Key Research and Development Program of China(2021YFB3700902)Key Research and Development Program of Shaanxi Province(2020ZDLGY13-06,2017ZDXM-GY-037)Shaanxi Province National Science Fund for Distinguished Young Scholars(2022JC-24)。
文摘A large-scale fine-grained Mg-Gd-Y-Zn-Zr alloy plate with high strength and ductility was successfully prepared by multi-pass friction stir processing(MFSP)technology in this work.The structure of grains and long period stacking ordered(LPSO)phase were characterized,and the mechanical properties uniformity was investigated.Moreover,a quantitative relationship between the microstructure and tensile yield strength was established.The results showed that the grains in the processed zone(PZ)and interfacial zone(IZ)were refined from 50μm to 3μm and 4μm,respectively,and numerous original LPSO phases were broken.In IZ,some block-shaped 18R LPSO phases were transformed into needle-like 14H LPSO phases due to stacking faults and the short-range diffusion of solute atoms.The severe shear deformation in the form of kinetic energy caused profuse stacking fault to be generated and move rapidly,greatly increasing the transformation rate of LPSO phase.After MFSP,the ultimate tensile strength,yield strength and elongation to failure of the large-scale plate were 367 MPa,305 MPa and 18.0% respectively.Grain refinement and LPSO phase strengthening were the major strengthening mechanisms for the MFSP sample.In particularly,the strength of IZ was comparable to that of PZ because the strength contribution of the 14H LPSO phase offsets the lack of grain refinement strengthening in IZ.This result opposes the widely accepted notion that IZ is a weak region in MFSP-prepared large-scale fine-grained plate.
文摘The effect of multi-pass friction stir processing(FSP)on the tribological properties of conventionally-cast Al−8.5Fe−1.3V−1.7Si(FVS0812)alloy was investigated.The pin-on-disk dry sliding wear tests were conducted at room temperature under the applied pressures of 0.25,0.50,and 0.75 MPa.The results showed that FSP substantially refined and improved the distribution of coarse¸-Al_(13)Fe4 platelets andα-Al_(12)(Fe,V)_(3)Si intermetallics in the microstructure of alloys and eliminated the intermetallic-related defects.Consequently,the mechanical properties of the alloys,especially their ductility,were improved,which enhanced the stability of the protective tribolayer formed on their worn surfaces.According to the wear test results,the FSPed samples showed improved tribological properties especially at the higher applied pressures.For instance,at the applied pressure of 0.75 MPa,the wear rate and average friction coefficient of four-pass FSPed sample were lower than those of the base as-cast sample by 97%and 52%,respectively.SEM examination of the worn surfaces and wear debris also demonstrated that the wear mechanism changed from severe delamination/abrasion and microcracking of the tribolayer in the as-cast samples to mild delamination/abrasion and minor plastic wear in the FSPed samples.
基金National Key Research and Development Program of China(2022YFB4600902)Shandong Provincial Science Foundation for Outstanding Young Scholars(ZR2024YQ020)。
文摘Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.
基金supported by National Natural Science Foundation of China(Grant No.52171032)Hebei Natural Science Foundation(Grant No.E2023501002)Fundamental Research Funds for the Central Universities(Grant No.2024GFYD003)。
文摘High entropy alloys(HEAs)have recently attracted significant attention due to their exceptional mechanical properties and potential applications across various fields.Friction stir welding and processing(FSW/P),as notable solid-state welding and processing techniques,have been proved effectiveness in enhancing microstructures and mechanical properties of HEAs.This review article summarizes the current status of FSW/P of HEAs.The welding materials and conditions used for FSW/P in HEAs are reviewed and discussed.The effects of FSW/P on the evolutions of grain structure,texture,dislocation,and secondary phase for different HEAs are highlighted.Furthermore,the influences of FSW/P on the mechanical properties of various HEAs are analyzed.Finally,potential applications,challenges,and future directions of FSW/P in HEAs are forecasted.Overall,FSW/P enable to refine grains of HEAs through dynamic recrystallization and to activate diverse deformation mechanisms of HEAs through tailoring phase structures,thereby significantly improving the strength,hardness,and ductility of both single-and dual-phase HEAs.Future progress in this field will rely on comprehensive optimization of processing parameters and alloy composition,integration of multi-scale modeling with advanced characterization for in-depth exploration of microstructural mechanisms,systematic evaluation of functional properties,and effective bridging of the gap between laboratory research and industrial application.The review aims to provide an overview of recent advancements in the FSW/P of HEAs and encourage further research in this area.
基金sponsored by the National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials Open Fund(No.2020009)the Natural Science Foundation of Guangdong Universities for Innovative Team(No.2020KCXTD043)+1 种基金the Natural Sciences and Engineering Research Council of Canada(NSERC)in the form of international research collaborationNSERC-Alberta Innovates for the financial support。
文摘A large-scale Mg-6Al-Zn plate was prepared by multi-pass submerged friction stir processing(M-SFSP)and its superplastic deformation behavior was investigated.The maximum elongation of 467%,332%and 421%was attained for the samples oriented in the processing direction(PD),45°tilted toward the PD,and transverse direction(TD),respectively,when deformed at 623 K and a strain rate of 1×10^(−3) s^(−1).This was attributed to the homogeneous and fine-grained structure with mostly high-angle grain boundaries facilitating the prevalent deformation mechanism of grain boundary sliding,along with the weakened texture and dynamic recrystallization during hot deformation.
基金supported by the National Natural Science Foundation of China(No.U23A20538)the Fundamental Research Funds for the Universities of Liaoning Province,Shenyang U40 Outstanding Youth Foundation(No.RC230864)+1 种基金the Foundation of CAS Henan Industrial Technology Innovation&Incubation Center(No.2024110)the Natural Science Foundation of Liaoning Province(No.2023-BS-016)。
文摘Interlayer friction stir processing(FSP)has been proved to be an efective method of enhancing the mechanical properties of wire arc-directed energy deposited(WA-DED)samples.However,the original deposition structure was still retained in the FSP-WA-DED component besides the processed zone(PZ),thus forming a composite structure.Considering the material utilization and practical service process of the deposited component,more attention should be paid on this special composite structure,but the relevant investigation has not been carried out.In this study,an Al–Mg–Sc alloy was prepared by WA-DED with interlayer FSP treatment,and the composite structure was frstly investigated.Almost all of the pores were eliminated under the pressure efect from the tool shoulder.The grains were further refned with an average size of about 1.2μm in the PZ.Though no severe plastic deformation was involved in the retained WA-DED deposition zone,comparable tensile properties with the PZ sample were obtained in the composite structure.Low ultimate tensile strength(UTS)of 289 MPa and elongation of 3.2%were achieved in the WA-DED sample.After interlayer FSP treatment,the UTS and elongation of the PZ samples were signifcantly increased to 443 MPa and 16.3%,while those in the composite structure remained at relatively high levels of 410 MPa and 13.5%,respectively.Meanwhile,a high fatigue strength of 180 and 130 MPa was obtained in the PZ and composite structure samples,which was clearly higher than that of the WA-DED sample(100 MPa).It is concluded that the defects in traditional WA-DED process can be eliminated in the composite structure after interlayer FSP treatment,resulting in enhanced tensile and fatigue properties,which provides an efective method of improving the mechanical properties of the WA-DED sample.
基金financially supported by the National Natural Science Foundation of China(No.52105373)the China Scholarship Council(No.202106020094).
文摘Ti-10V-2Fe-3Al alloy with fine-grainedβphases was fabricated by friction stir processing with opti-mized processing parameters.The superplastic behavior of the specimens was investigated by tensile deformation at different strain rates and temperatures,and an optimal superplastic elongation of 634%was achieved at 700℃ and 3×10^(-4)/s.An annealing treatment at 650℃ for 60 min showed a mi-crostructure withαprecipitates distributed in theβmatrix in the friction stir specimen.Such pre-heat treatment improves the superplasticity of the specimen,achieving an elongation of up to 807%at 750℃ and 3×10^(-4)/s.The influences of tensile temperatures and strain rates on the microstructural evolution,such as grain size variation,grain morphology,and phase transformations,were discussed.The super-plastic deformation behavior of fine-grained Ti-10V-2Fe-3Al alloy is controlled by grain boundary sliding and accompanied by dynamic phase transformation and recrystallization.
基金financial support from the National Key Research and Development Program of China(2021YFC2400703)Zhengzhou City Major Special Project for Collaborative InnovationChina Scholarship Council。
文摘Bio-magnesium(Mg)alloys exhibit excellent biocompatibility and biodegradability,making them highly promising for implant applications.However,their limited strength-ductility balance remains a critical challenge restricting widespread use.In this study,ultra-fine-grained and homogeneous Mg alloys were fabricated using double-sided friction stir processing(DS-FSP)with liquid CO_(2) rapid cooling,leading to a significant enhancement in the strength-ductility synergy of the stirred zone.The results demonstrate that DS-FSP samples exhibit simultaneous improvements in ultimate tensile strength(UTS)and elongation,reaching 334.1±15 MPa and 28.2±7.3%,respectively.Compared to the non-uniform fine-grained microstructure obtained through single-sided friction stir processing,DS-FSP generates a uniform ultra-fine-grained structure,fundamentally altering the fracture behavior and mechanisms of Mg alloys.The DS-FSP samples exhibit irregular fracture patterns due to variations in basal slip system activation among different grains.In contrast,single-sided friction stir processing samples,characterized by a fine-grained yet heterogeneous microstructure,display flat shear fractures dominated by high-density dislocation initiation induced by twin formation,with fracture propagation dictated by the non-uniform texture.By achieving an ultra-fine grain size and homogeneous texture,DS-FSP effectively modifies the fracture mechanisms,thereby enhancing the strength-ductility balance of bio-magnesium alloys.
基金financially supported by the National Natural Science Foundation of China(Nos.52272283,52311530772,and 52274387)the Science and Technology Commission of Shanghai Municipality(No.22S31902900)+4 种基金the Shanghai Medical Key Specialty(No.2024ZDXK0048)the Medical Key Subject of Xuhui District(No.SHXHZDXK202302)the National Key Research and Development Program of China(No.2024YFE0109000)the Medical-Engineering Cross Foundation of Shanghai Jiao Tong University(No.YG2024LC04)the Institute-level Research Project of Xuhui District Dental Center(No.SHXYF202212).
文摘To promote early rapid osteogenesis and prevent late implant-related infection,it is critical to develop ef-fective and reliable surface treatment technologies for enhancing both osteogenic and antibacterial prop-erties of titanium alloy implants.Reduced graphene oxide(rGO)is considered a promising modification candidate.However,whether rGO retains its osteogenic and antibacterial functions after being applied to modify titanium alloy surfaces depends on the surface treatment technology employed.In this study,rGO was integrated onto the surface of Ti-35Nb-2Ta-3Zr(TNTZ)alloy through friction stir processing(FSP),yielding a consolidated TNTZ/F-rGO composite.The incorporation of rGO not only significantly im-proved the microhardness and hydrophilicity of the material,but also exhibited positive biological effects in vitro experiments:it effectively promoted the proliferation,osteogenic differentiation,alkaline phos-phatase(ALP)production and extracellular matrix mineralization of BMSCs.Furthermore,TNTZ/F-rGO ex-hibited potent antibacterial activity via surface-contact mechanisms.In summary,the rGO-modified in-tegrated titanium alloy has excellent osteogenic properties and high-efficiency antibacterial ability.This study provides new insights and strategies for the design of graphene-based biomaterials and implant surface modification technologies.
基金the financial support from the Shandong Provincial Science Foundation for Outstanding Young Scholars(Grant No ZR2024YQ020)the National Natural Science Foundation of China(Grant Nos.52275349 and 52035005)+3 种基金the National Key Research and Development Program of China(Grant No 2022YFB4600902)the Excellent Young Team Project of Central Universities(No.2023QNTD002)Key Research and Development Program of Shandong Province(Grant No 2021ZLGX01)sponsored by the China/Shandong University International Postdoctoral Exchange Program.
文摘The inherent trade-off between ductility and strength in Mg alloys remains a significant challenge,primarily governed by microstructural distribution and texture characteristics.Friction stir processing(FSP),a severe plastic deformation(SPD)technique,refines microstructures by generating fine grains,uniformly dispersed fragmented particles,and a high fraction of high-angle grain boundaries(HAGBs),thereby facilitating superplastic forming at high strain rates and low temperatures.In the present work,a dual eccentric-pin tool(DEPT)FSP was employed to incorporate ZrO_(2) particles into a 6 mm thick AZ91D Mg alloy,leading to the formation of high volume{10-12}twins,dislocations,and β-Mg_(17)Al_(12) precipitates within the stirred zone.The microstructural evolution and mechanical behaviour of the stir zone under various process parameters were analysed using scanning electron microscopy(SEM),X-ray diffraction(XRD),electron backscatter diffraction(EBSD),and transmission electron microscopy(TEM).The DEPT enhanced plastic shearing and dynamic recrystallization,significantly reducing the grain size from 15.6μm to 2.35μm while promoting uniform dislocation distribution within the stir zone(SZ).Grain orientation analysis revealed a transition from basal to prismatic texture dominance(29.3% volume fraction)due to intensified radial-tangential coupling shear deformation,facilitating the activation of non-basal slip systems.The DEPT evidently improved the hardness of the SZ from 58 to 92 HV and increased tensile strength from 234 MPa to 325 MPa while maintaining an elongation of 23.8%,achieving an optimal strengthductility balance.This work presents a one-step approach for tailoring microstructural heterogeneity and enhancing mechanical properties in AZ91D/ZrO_(2) composites using the DEPT FSP technique.The method provides an effective strategy for mitigating the strength-ductility trade-off commonly observed in Mg alloys.
基金supported by Yunnan Major Scientific and Technological Projects(Grant No 202202AG050011)the Sichuan Science and Technology Program(No.2023YFG0218)+2 种基金Guizhou Provincial Department of Education Open Recruitment and Leadership Scientific and Technological Attack Project(Guizhou Education Technology[2024]No 003)Anshu University 2024 Annual School-Level Scientific Research Project(asxybsjj202413)Guizhou Provincial Basic Research Program(Natural Science)(No.QKHJC[2024]Youth 214).
文摘A novel Mg_(98.5)Zn_(0.5)Y alloy sheet with ultrafine grains and exceptional electromagnetic shielding performance has been fabricated using friction stir processing(FSP).This study investigates the impact of FSP on the microstructure,mechanical properties,and electromagnetic interference(EMI)shielding effectiveness(SE)of the alloy,specifically across three distinct layers within the stir zone(SZ):Top,Middle,and Bottom.The results reveal that the Mg_(12)YZn long-period stacking ordered(LPSO)phase is the predominant structure,undergoing significant grain refinement.The grain size is drastically reduced from 1.5 mm in the as-cast state to 12.6μm,10.0μm,and 7.1μm in the Top,Middle,and Bottom,respectively.This grain refinement and fragmentation of the LPSO phase into nanoscale particles result in a substantial enhancement of mechanical properties.The ultimate tensile strength(UTS)reached 358.2 MPa with an elongation(EL)of 15.1%,reflecting a 344% increase in strength and a 733% improvement in ductility compared to the as-cast material.Simultaneously,the EMI SE was maintained between 70 and 110.4 dB over a broad frequency range(30-4500 MHz).Despite the nanoscale LPSO particles contributing minimally to EMI shielding,the lamellar LPSO structure demonstrated excellent performance through multiple electromagnetic wave reflections within the matrix.These findings underscore the dual benefits of FSP in improving both mechanical strength and electromagnetic shielding effectiveness,positioning this Mg_(98.5)Zn_(0.5)Y alloy for advanced applications in the electronics and telecommunications sectors.
基金Project (2009Z2-D811) supported by Guangzhou Science and Technology Development Program, ChinaProject (2009ZM0264) supported by the Fundamental Research Funds for the Central Universities, China
文摘Microstructure and tensile behaviors of AZ31 magnesium alloy prepared by friction stir processing（FSP） were investigated.The results show that microstructure of the AZ31 hot-rolled plate with an average grain size of 92.0 μm is refined to 11.4 μm after FSP.The FSP AZ31 alloy exhibits excellent plasticity at elevated temperature,with an elongation to failure of 1050% at 723 K and a strain rate of 5×10-4 s-1.The elongation of the FSP material is 268% at 723 K and 1×10-2 s-1,indicating that high strain rate superplasticity could be achieved.On the other hand,the hot-rolled base material,which has a coarse grain structure,possesses no superplasticity under the experimental conditions.
基金Projects(51571214,51301205,51101126)supported by the National Natural Science Foundation of ChinaProject(P2014-07)supported by the Open Fund of State Key Laboratory of Materials Processing and Die&Mould Technology,China+4 种基金Project(20130162120001)supported by the Specialized Research Fund for the Doctoral Program of Higher Education of ChinaProject(K1308034-11)supported by the Changsha Municipal Science and Technology Plan,ChinaProjects(2015GK3004,2015JC3006)supported by the Science and Technology Project of Hunan Province,ChinaProject supported by the Innovation-driven Plan in Central South University,ChinaProject supported by the Independent Project of State Key Laboratory of Powder Metallurgy of Central South University,China
文摘The ultra-fine structured Ni?Al?WC layer with interlocking bonding was fabricated on austenitic stainless steel by combination of laser clad and friction stir processing (FSP). Laser was initially applied to Ni?Al elemental powder preplaced on the austenitic stainless steel substrate to produce a coating for further processing. The as-received coating was subjected to FSP treatment, processed by a rotary tool rod made of WC?Co alloy, to obtain sample for inspection. Microstructure, phase constitutions, hardness and wear property were investigated by methods of scanning electronic microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX) microanalysis, and X-ray diffraction (XRD), hardness test alongside with dry sliding wear test. The results show that the severe deformation effect exerted on the specimen resulted in an ultra-fine grain layer of about 100μmin thickness and grain size of 1?2μm. Synergy between introduction of WC particles to the deformation layer and deformation strengthening contributes greatly to the increase in hardness and friction resistance. An interlocking bonding between the coating and matrix which significantly improves bonding strength was formed due to the severe deformation effect.
文摘The effects of friction stir processing （FSP） on the microstructure, microtexture and hardness of rolled pure aluminum were investigated. The microstructure and microtexture were characterized using electron backscattered diffraction （EBSD） technique on the transversal section. The stir zone （SZ） contains fine, equiaxed and fully recrystallized grains. The texture component of the base material mainly consists of R, S and brass R textures. Miner copper texture component is also determined. In the center of the stir zone, the dominant texture is （111） parallel to about 70° from ND pointing toward RD. The textures of this location rotating clockwise about 30° and anticlockwise about 60° around the ND result in the textures of the areas, which are 3 mm apart from this location on the retreating side and advancing side, respectively.
基金sponsorship from the National Natural Science Foundation of China(Nos.51574192,51404180,51974220,and U1760201)the Key Industrial Research Program of Shaanxi Province,China(No.2017ZDXMGY-037)+1 种基金the National Key Research and Development Program of China(No.Z20180407)the Youth Innovation Team of Shaanxi Universities(No.2019-2022).
文摘Magnesium(Mg)alloys have been extensively used in various fields,such as aerospace,automobile,electronics,and biomedical industries,due to their high specific strength and stiff ness,excellent vibration absorption,electromagnetic shielding eff ect,good machinability,and recyclability.Friction stir processing(FSP)is a severe plastic deformation technique,based on the principle of friction stir welding.In addition to introducing the basic principle and advantages of FSP,this paper reviews the studies of FSP in the modification of the cast structure,superplastic deformation behavior,preparation of finegrained Mg alloys and Mg-based surface composites,and additive manufacturing.FSP not only refines,homogenizes,and densifies the microstructure,but also eliminates the cast microstructure defects,breaks up the brittle and network-like phases,and prepares fine-grained,ultrafine-,and nano-grained Mg alloys.Indeed,FSP significantly improves the comprehensive mechanical properties of the alloys and achieves low-temperature and/or high strain rate superplasticity.Furthermore,FSP can produce particle-and fiber-reinforced Mg-based surface composites.As a promising additive manufacturing technique of light metals,FSP enables the additive manufacturing of Mg alloys.Finally,we prospect the future research direction and application with friction stir processed Mg alloys.
基金the support of the National Basic Research Program,China(Grant Nos.2011CB932603 and 2012CB619600)the National Natural Science Foundation, China(Grant No.51331008)
文摘A route combining powder metallurgy and subsequent friction stir processing was utilized to fabricate carbon nanotube （CNT） reinforced AI （CNT/AI） and 6061AI （CNT/6061AI） composites. Microstructural observations indicated that CNTs were uniformly dispersed in the matrix in both CNT/AI and CNT/6061AI composites. Mg and Si elements tended to segregate at CNT-AI interfaces in the CNT/6061AI composite during artificial aging treatment. The tensile properties of both the AI and 6061AI were increased by CNT incorporation. The electrical conductivity of CNT/AI was decreased by CNT addition, while CNT/6061AI exhibited an increase in electrical conductivity due to the Mg and Si segregation.
