The compromise between strength and plasticity has greatly limited the potential application of particles reinforced magnesium matrix composites(MMCs).In this work,the Ti particles reinforced AZ31 magnesium(Mg)matrix ...The compromise between strength and plasticity has greatly limited the potential application of particles reinforced magnesium matrix composites(MMCs).In this work,the Ti particles reinforced AZ31 magnesium(Mg)matrix composites achieved simultaneous improvement in strength,elongation and wear resistance.The Ti particles reinforced AZ31 composites were fabricated by ultrasonic-assisted stir casting with hot extrusion.The results showed that a strong interfacial bonding was obtained at Ti/Mg interface because of the formation of semicoherent orientation relationship of Ti Al/Mg,Ti Al/Al_(2)Ti and Al_(2)Ti/Mg interfaces.The as-extruded 6 wt.%Ti/AZ31 composite presented the best compressive mechanical properties and wear resistance with ultimate tensile strength,elongation and wear rate of 327 MPa,20.4%and 9.026×10^(-3)mm^(3)/m,obviously higher than those of AZ31 alloys.The enhanced mechanical properties were attributed to the grain refinement and strong interfacial bonding.The improved wear resistance was closely related to the increased hardness of composites and the formation of protective oxidation films.展开更多
Spherical micro-Ti particle(TiP)-reinforced AZ91 magnesium alloy composites were fabricated by semi-solid stirring assisted ultrasonic vibration,which were then subjected to hot extrusion.The microstructure results sh...Spherical micro-Ti particle(TiP)-reinforced AZ91 magnesium alloy composites were fabricated by semi-solid stirring assisted ultrasonic vibration,which were then subjected to hot extrusion.The microstructure results showed that the addition of Ti particles refined the grain size and decreased the texture intensity of the as-extruded AZ91 alloy.An Al3Ti phase with a thickness of 100 nm formed at the Ti/Mg interface,which had a non-coherent relationship with the magnesium matrix.The as-extruded 1 vol.%TiP/AZ91 composite exhibited the best comprehensive mechanical properties,with yield strength,ultimate tensile strength,and elongation at break of 366 MPa,456 MPa,and 14.6%,respectively,which were significantly higher than those of the AZ91 alloy.Therefore,the addition of Ti particles can improve the strength and ductility of the AZ91 alloy,demonstrating the value of magnesium matrix composites for commercial applications.展开更多
The ageing behavior of as-extruded Ti_(P)/VW94 composites was investigated.The peak hardness of the composites increases compared to the matrix alloy and the 5%Ti_(P)/VW94 composite presents the highest peak hardness ...The ageing behavior of as-extruded Ti_(P)/VW94 composites was investigated.The peak hardness of the composites increases compared to the matrix alloy and the 5%Ti_(P)/VW94 composite presents the highest peak hardness of 148.7 HV after aging for about 50 h.However,the hardness increments first decrease and then slightly increase with increasing Ti particle content due to the introduction of high-density dislocations by Ti particles.展开更多
Mg matrix composites were often reinforced by non-deformable ceramic particles.In this paper,a novel Mg matrix composite reinforced with deformable TC4(Ti-6Al-4 V)particles was fabricated and then extruded.The evoluti...Mg matrix composites were often reinforced by non-deformable ceramic particles.In this paper,a novel Mg matrix composite reinforced with deformable TC4(Ti-6Al-4 V)particles was fabricated and then extruded.The evolutions of microstructure and mechanical properties of the composite during hot extrusion were investigated.Hoi extrusion refined giains and eliminated the segregation of TC4 particles.TC4 particles,as deformable particles,stimulated the nucleation of dynamic recrystallization during extrusion.However,since the deformation of TC4 particles partly released the stress concentrations around them,the recrystallized grains are just slightly smaller around TC4 particles than that away from them,which is evidently different from the case in Mg matrix composites reinforced by non-deformable ceramic particles.Compared with AZ91 matrix composites reinforced by SiC particles,the present composite possesses the superior comprehensive mechanical properties,which are attributed to not only the strong interfacial bonds between TC4p and matrix but also the deformability of TC4 particles.展开更多
A novel Ti/Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 composite was successfully prepared by infiltrating the melt into sintered Ti preform. It shows that the introduction of Ti particles into the composite results in an increase...A novel Ti/Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 composite was successfully prepared by infiltrating the melt into sintered Ti preform. It shows that the introduction of Ti particles into the composite results in an increase in elastic strain to 3% and an enhancement of the strength up to 2.1 GPa. High specific strength has been obtained because of the decrease in density of the composite. It is suggested that an improvement in the mechanical properties of the composite may be attributed to the generation of multiple shear bands and some deformation in the Ti particles.展开更多
In the field of particle reinforced magnesium(Mg)matrix composites(MMCs),the interfacial microstructures between reinforcements and Mg matrix are a subject of interest for most researchers.In this work,the 2 wt.%Ti pa...In the field of particle reinforced magnesium(Mg)matrix composites(MMCs),the interfacial microstructures between reinforcements and Mg matrix are a subject of interest for most researchers.In this work,the 2 wt.%Ti particle reinforced Mg-6Zn alloy composites with different contents(0,0.5,1,1.5,2 wt.%)of Mn were prepared using semi-solid stirring assisted ultrasonic treatment followed by hot extrusion.With the increment of Mn element,the characteristics of mixed-grain structure became obvious and the DRX was inhibited.Meanwhile,the interfacial product gradually changed from MgZn_(2)to Mn_(2)Ti.The tensile test demonstrated that the 2Ti/Mg-6Zn-1.5Mn composite exhibited an excellent strength-ductility synergy,achieving the highest yield stress(YS),ultimate tensile stress(UTS)of 239 MPa,366 MPa,respectively,along with a notable elongation(El.)of 20.6%.The increased strength is mainly due to the grain refinement,the precipitation strengthening,the HDI strengthening and the strong interfacial bonding including the tightly Ti/Mn_(2)Ti bonding and the Mn_(2)Ti/Mg coherent orientation relationship.The ideal El.is the result of fine/coarse bimodal structure and the proper interfacial reaction,which can reduce the occurrence of cracks.展开更多
Novel Ti6Al4V particles-reinforced AZ91 Mg matrix composites were successfully fabricated by stir casting method. The stirring time in semisolid condition directly affected the particle distribution and the quality of...Novel Ti6Al4V particles-reinforced AZ91 Mg matrix composites were successfully fabricated by stir casting method. The stirring time in semisolid condition directly affected the particle distribution and the quality of the ingots. Furthermore, the optimal speed of the heating and the liquid stirring could overcome particle settlement caused by the density difference between the matrix and the particles. Ti6Al4V particles distributed uniformly in the composites with different particle contents. The average grain size decreased with the increase in the particle contents. The Ti6A14V particles bonded pretty well with the alloy matrix. In addition, there were some interfacial reactions in the composites. There were rod-like A13Ti phases at the interface. The precipitates extended from the particle surface to the matrix, and they might improve the interfacial bonding strength. The ultimate tensile strength, yield strength and elastic modulus were enhanced as the particle contents increased, and the elongation was much better than that of the same matrix material reinforced with SiC particles. Thus, the novel composites exhibit better comprehensive mechanical properties.展开更多
Fe-based alloy layer reinforced by Ti（C,N） particles was produced on the surface of cast steel. X ray dif fraction （XRD） was used for phase identification in the composite coating. The microstructure of laser clad...Fe-based alloy layer reinforced by Ti（C,N） particles was produced on the surface of cast steel. X ray dif fraction （XRD） was used for phase identification in the composite coating. The microstructure of laser cladding layer was analyzed by means of optical microscope （OM）, electron probe microscope analyzer （EPMA）, scanning electron microscope （SEM） and transmission electron microscope （TEM）. The results show that Ti（C0.3 N0.7 ） particle is in-troduced by an in situ metallurgical reaction of TiN particle and graphite powder in the process of laser cladding. The shape of lots of Ti（C0.3 N0.7） particle is irregular. The sizes of Ti（C0. 3N0. 7） particles range from 0. 1 to 6.0 μm, and they are dispersed evenly in the matrix, which is fine dendritic or cellular crystal. A new kind of phase named Ti（C0.3 N0. 7 ） parti-cles are tightly bonded with α-Fe microstructure, and there is a clean and smooth phase interface between ceramic re-inforcement phase and the matrix.展开更多
The Martensite formed at low temperatures in Fe-Ni-Co-Ti alloys is featured as thin plate when the size of γ' dispersively precipitated particles was about 20—50 nm.The interface of martensite plate is not smoot...The Martensite formed at low temperatures in Fe-Ni-Co-Ti alloys is featured as thin plate when the size of γ' dispersively precipitated particles was about 20—50 nm.The interface of martensite plate is not smooth.If the γ'particles are sized less than 5 nm,the thin plate martensite with thermoelastisity may be found at low temperatures,whi greater than 5 nm, intermittent martensite may occur,and the plate martensite increases both in size and quantity with the coarsening of the γ particles.The lenticular or butterfly martensite forms at low tem- peratures until the γ' particles are up to 10—5 nm.展开更多
A novel and simple strategy of morphology-controlled Sr Ti O3（ST） micro-scale particle synthesis by the flux method is reported. Systematic experiments are designed to realize the tunable morphologies of the particl...A novel and simple strategy of morphology-controlled Sr Ti O3（ST） micro-scale particle synthesis by the flux method is reported. Systematic experiments are designed to realize the tunable morphologies of the particles when the flux salt,sintering process, and the precursors are changed. The ST plates can be synthesized by plate-like Bi4Ti3O12（BIT） precursors in Na Cl flux. However, the as-synthesized Bi4Ti3O12 grains transform into reticular particles and finally into rods at higher temperature in Na Cl and KCl compounds. Besides, cubic ST particles are also prepared using different precursors as a comparative experiment. This study provides a strategy for further investigations in designing the morphology-controlled particles and efficient anisotropic materials of perovskite structure such as ferroelectric and photocatalyst.展开更多
There are few studies on the preparation of magnesium matrix composites(MMCs)by rapid solidification.This study aims to add minor amounts of Ti particles to AZ91 alloy and prepare AZ91/Ti_(P) MMC ribbon by Melt-Spinni...There are few studies on the preparation of magnesium matrix composites(MMCs)by rapid solidification.This study aims to add minor amounts of Ti particles to AZ91 alloy and prepare AZ91/Ti_(P) MMC ribbon by Melt-Spinning(MS).The effects of Ti particle content on the microstructure and mechanical properties of AZ91/Ti_(P) ribbon were studied by scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),X-ray diffraction(XRD),transmission electron microscopy(TEM),three-dimensional profiling(3D-P)and calculation of supercooling rate.The results show that the grain refinement of AZ91 ribbon prepared by rapid solidification is very significant and the grain refinement is further improved with the increase of Ti particle content;at the same time,the growth of β-Mg_(17)Al_(12) is inhibited,and the interface reaction between Ti and Mg leads to the formation of interfaces around Ti particles.These nano-scale Ti_(3)Al and Al_(3)Ti interface compounds uniformly wrap the Ti particles.It is believed that the addition of Ti particles not only helps to refine the surrounding grains,but also increases the dislocations in the MMC ribbon and forms a good interface,thereby improving the mechanical properties.Compared with AZ91 alloy ribbon,the yield strength and tensile strength of MMC material containing 5 wt.%Ti particles increased by 25.0%and 22.7% respectively.The elongation only decreased by 10.9%.AZ91/5 wt.%Ti_(P) ribbon has a better balance between high strength and high elongation.The analysis shows that the strengthening effect of this mechanical property is mainly attributed to fine grain strengthening,dislocation strengthening and non-basal slip.展开更多
SiC/7075 aluminum matrix composites were prepared by a liquid stirring method.The role of Ti facilitating the preparation of SiC/7075 aluminum matrix were studied by means of direct-reading spectrometer,scanning elect...SiC/7075 aluminum matrix composites were prepared by a liquid stirring method.The role of Ti facilitating the preparation of SiC/7075 aluminum matrix were studied by means of direct-reading spectrometer,scanning electron microscope,energy dispersive spectrometer,X-ray diffraction and the sessile drop method.The results show that the SiC content in the SiC/7075 composite increases with an increase of Ti addition.The addition of Ti can significantly improve the wettability of SiC/Al system,there is a critical value of above 0.5%of Ti content in improving the wettability of the Al/SiC system at 1173K.The temperature of the"non wetting-wetting"transition for the(Al-2Ti)/SiC system is about 1123K,the contact angle decreases to 88°at 200 seconds and reaches a stable contact angle of 28°at 2100 seconds.展开更多
In this paper, in situ （Ti, Nb）C particle （（Ti, Nb）Cp） reinforced Fe-based composite coatings were produced by laser cladding on the surface of the high carbon steel. The effects of heat input on the microstruct...In this paper, in situ （Ti, Nb）C particle （（Ti, Nb）Cp） reinforced Fe-based composite coatings were produced by laser cladding on the surface of the high carbon steel. The effects of heat input on the microstructure, distribution characteristics of particle, and mechanical properties of the coating were investigated. The results show that （Ti, Nb）C multiple carbide particle is synthesized during solidification of molten pool. The size of particle coarsens gradually, the area ratio of particle increases, and the amount of particles presents a non-monotonous variation with the increase in energy density. The mechanical properties of the coating are improved dramatically compared with those of the substrate, benefiting from its higher hardness and dispersed in situ （Ti, Nb）Cp in it. With the change in heat input, the mechanical performances of the coating vary except the hardness. When energy density is 1 × 10^5 J.mm-2, tensile strength and wear resistance of the coating achieve optimal value due to moderate content and size of the particle in the coating.展开更多
（Ti, Nb）C reinforced Fe based laser coatings were prepared with normal and high scanning velocities of the laser beam. The distribution characteristics of reinforced particles in the coatings were investigated. The ...（Ti, Nb）C reinforced Fe based laser coatings were prepared with normal and high scanning velocities of the laser beam. The distribution characteristics of reinforced particles in the coatings were investigated. The mechanical properties of coatings were tested. The results showed that the morphologies of the microstructure and the reinforced particle changed dramatically at high solidification rate due to rapid laser processing compared with that prepared by normal processing. Two kinds of particles were observed in the coating. One was （Ti, Nb）C multiple carbide particle with the size of micron and sub micron scales, in which a mass of dislocations were found. Another was nano sized particle including a Fe and （Ti, Nb）C obtained by rapid solidification. The microstructure of the coatings was highly refined and a large number of twin crystals were found in matrix. The resuhs of mechanical properties test revealed that the wear resistance of the coaling was improved by rapid laser processing, compared with that of the coating prepared with normal speeds. The ahove-mentioned conclusion indicated that rapid laser cladding can promote not on ly the processing efficiency but also lhe mechanical properties of the coating.展开更多
In this study,the hot rolled medium manganese steel containing titanium was solution treated at 1,000°C and followed by aging treatment at 500,550,and 600°C.The influence of aging treatment on mechanical pro...In this study,the hot rolled medium manganese steel containing titanium was solution treated at 1,000°C and followed by aging treatment at 500,550,and 600°C.The influence of aging treatment on mechanical properties and wear resistance of medium manganese steel reinforced with Ti(C,N)particles was investigated.It was found that the matrix of medium manganese steel was austenite.The austenite grain size was refined,and Ti(C,N)particles were precipitated after aging treatment.Compared to that of the as-hot rolled sample,the initial hardness of 500°C aged sample increased by 9.5%to 312.86 HV,whose impact energy was more than doubled to 148.5 J.As the aging temperature raised to 600°C,the initial hardness changed slightly.However,the impact energy dropped significantly to 8 J due to the aggregation of Mn at the grain boundaries.In addition,the main wear mechanisms of the samples were fatigue wear and abrasive wear.It was worth noting that 500°C aged sample exhibited the best wear resistance under a 300 N applied load,whose wear loss was just half of the as-hot rolled sample.The relationship between wear loss and mechanical properties indicated that the wear resistance of medium manganese steel was independent of the initial hardness.The large difference in the wear resistance was predominately due to the outstanding work hardening ability of 500°C aged sample,whose strengthening mechanisms were contributed from transformation induced plasticity(TRIP)effect,dislocation strengthening,twinning induced plasticity(TWIP)effect,and precipitation strengthening.展开更多
基金the financial supports from the Guangdong Major Project of Basic and Applied Basic Research(2020B0301030006)the National Natural Science Foundation of China(Nos.52171103,52171133)+3 种基金the Natural Science Foundation of Chongqing(cstc2019jcyjmsxm X0234)the“111 Project”(B16007)by the Ministry of Educationthe Fundamental Research Funds for the Central Universities(No.2020CDJDPT001)Graduate Research and Innovation Foundation of Chongqing,China(No.CYB21001)。
文摘The compromise between strength and plasticity has greatly limited the potential application of particles reinforced magnesium matrix composites(MMCs).In this work,the Ti particles reinforced AZ31 magnesium(Mg)matrix composites achieved simultaneous improvement in strength,elongation and wear resistance.The Ti particles reinforced AZ31 composites were fabricated by ultrasonic-assisted stir casting with hot extrusion.The results showed that a strong interfacial bonding was obtained at Ti/Mg interface because of the formation of semicoherent orientation relationship of Ti Al/Mg,Ti Al/Al_(2)Ti and Al_(2)Ti/Mg interfaces.The as-extruded 6 wt.%Ti/AZ31 composite presented the best compressive mechanical properties and wear resistance with ultimate tensile strength,elongation and wear rate of 327 MPa,20.4%and 9.026×10^(-3)mm^(3)/m,obviously higher than those of AZ31 alloys.The enhanced mechanical properties were attributed to the grain refinement and strong interfacial bonding.The improved wear resistance was closely related to the increased hardness of composites and the formation of protective oxidation films.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research (2020B0301030006)the Guangdong Academy of Sciences'Project of Science and Technology Development (2020GDASYL-20200101001).
文摘Spherical micro-Ti particle(TiP)-reinforced AZ91 magnesium alloy composites were fabricated by semi-solid stirring assisted ultrasonic vibration,which were then subjected to hot extrusion.The microstructure results showed that the addition of Ti particles refined the grain size and decreased the texture intensity of the as-extruded AZ91 alloy.An Al3Ti phase with a thickness of 100 nm formed at the Ti/Mg interface,which had a non-coherent relationship with the magnesium matrix.The as-extruded 1 vol.%TiP/AZ91 composite exhibited the best comprehensive mechanical properties,with yield strength,ultimate tensile strength,and elongation at break of 366 MPa,456 MPa,and 14.6%,respectively,which were significantly higher than those of the AZ91 alloy.Therefore,the addition of Ti particles can improve the strength and ductility of the AZ91 alloy,demonstrating the value of magnesium matrix composites for commercial applications.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research (No.2020B0301030006)the National Natural Science Foundation of China (No.52225101)+1 种基金the Graduate Research and Innovation Foundation of Chongqing,China (Grant No.CYB21001)the GDAS'Project of Science and Technology Development (No.2020GDASYL-20200101001).
文摘The ageing behavior of as-extruded Ti_(P)/VW94 composites was investigated.The peak hardness of the composites increases compared to the matrix alloy and the 5%Ti_(P)/VW94 composite presents the highest peak hardness of 148.7 HV after aging for about 50 h.However,the hardness increments first decrease and then slightly increase with increasing Ti particle content due to the introduction of high-density dislocations by Ti particles.
基金This work was supported by“‘National Key R&D Program of China’”2017YFB0703100)“National Natural Science Foundation of China”(Grant Nos.51471059 and 51671066),Key Laboratory of Superlight Materials&Surface Technology(Harbin Engineering University),Ministry of Education and Key Laboratory of Lightweight and High Strength Struc-tural Materials of Jiangxi Province.
文摘Mg matrix composites were often reinforced by non-deformable ceramic particles.In this paper,a novel Mg matrix composite reinforced with deformable TC4(Ti-6Al-4 V)particles was fabricated and then extruded.The evolutions of microstructure and mechanical properties of the composite during hot extrusion were investigated.Hoi extrusion refined giains and eliminated the segregation of TC4 particles.TC4 particles,as deformable particles,stimulated the nucleation of dynamic recrystallization during extrusion.However,since the deformation of TC4 particles partly released the stress concentrations around them,the recrystallized grains are just slightly smaller around TC4 particles than that away from them,which is evidently different from the case in Mg matrix composites reinforced by non-deformable ceramic particles.Compared with AZ91 matrix composites reinforced by SiC particles,the present composite possesses the superior comprehensive mechanical properties,which are attributed to not only the strong interfacial bonds between TC4p and matrix but also the deformability of TC4 particles.
基金This study was financially supported by the National Natural Science Foundation of China (No.50431030, No.59871025, and No.50171006).
文摘A novel Ti/Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 composite was successfully prepared by infiltrating the melt into sintered Ti preform. It shows that the introduction of Ti particles into the composite results in an increase in elastic strain to 3% and an enhancement of the strength up to 2.1 GPa. High specific strength has been obtained because of the decrease in density of the composite. It is suggested that an improvement in the mechanical properties of the composite may be attributed to the generation of multiple shear bands and some deformation in the Ti particles.
基金the Guangdong Major Project of Basic and Applied Basic Research(2020B0301030006)National Natural Science Foundation of China(52225101 and 52101123)+2 种基金Fundamental Research Funds for the Central Universities(2023CDJYXTD-002)Support Program for Overseas Educated Students Returning to China for Entrepreneurship and Innovation(cx2023020)Chongqing Natural Science Foundation of China(CSTB2023NSCQ-MSX0571).
文摘In the field of particle reinforced magnesium(Mg)matrix composites(MMCs),the interfacial microstructures between reinforcements and Mg matrix are a subject of interest for most researchers.In this work,the 2 wt.%Ti particle reinforced Mg-6Zn alloy composites with different contents(0,0.5,1,1.5,2 wt.%)of Mn were prepared using semi-solid stirring assisted ultrasonic treatment followed by hot extrusion.With the increment of Mn element,the characteristics of mixed-grain structure became obvious and the DRX was inhibited.Meanwhile,the interfacial product gradually changed from MgZn_(2)to Mn_(2)Ti.The tensile test demonstrated that the 2Ti/Mg-6Zn-1.5Mn composite exhibited an excellent strength-ductility synergy,achieving the highest yield stress(YS),ultimate tensile stress(UTS)of 239 MPa,366 MPa,respectively,along with a notable elongation(El.)of 20.6%.The increased strength is mainly due to the grain refinement,the precipitation strengthening,the HDI strengthening and the strong interfacial bonding including the tightly Ti/Mn_(2)Ti bonding and the Mn_(2)Ti/Mg coherent orientation relationship.The ideal El.is the result of fine/coarse bimodal structure and the proper interfacial reaction,which can reduce the occurrence of cracks.
基金supported by the National Natural Science Foundation of China (Grant No. 51471059)the China Postdoctoral Science Foundation (Grant No. 2014T70328)
文摘Novel Ti6Al4V particles-reinforced AZ91 Mg matrix composites were successfully fabricated by stir casting method. The stirring time in semisolid condition directly affected the particle distribution and the quality of the ingots. Furthermore, the optimal speed of the heating and the liquid stirring could overcome particle settlement caused by the density difference between the matrix and the particles. Ti6Al4V particles distributed uniformly in the composites with different particle contents. The average grain size decreased with the increase in the particle contents. The Ti6A14V particles bonded pretty well with the alloy matrix. In addition, there were some interfacial reactions in the composites. There were rod-like A13Ti phases at the interface. The precipitates extended from the particle surface to the matrix, and they might improve the interfacial bonding strength. The ultimate tensile strength, yield strength and elastic modulus were enhanced as the particle contents increased, and the elongation was much better than that of the same matrix material reinforced with SiC particles. Thus, the novel composites exhibit better comprehensive mechanical properties.
基金Item Sponsored by Higher Education Fund of Inner Mongolia of China(nyzy11266)
文摘Fe-based alloy layer reinforced by Ti（C,N） particles was produced on the surface of cast steel. X ray dif fraction （XRD） was used for phase identification in the composite coating. The microstructure of laser cladding layer was analyzed by means of optical microscope （OM）, electron probe microscope analyzer （EPMA）, scanning electron microscope （SEM） and transmission electron microscope （TEM）. The results show that Ti（C0.3 N0.7 ） particle is in-troduced by an in situ metallurgical reaction of TiN particle and graphite powder in the process of laser cladding. The shape of lots of Ti（C0.3 N0.7） particle is irregular. The sizes of Ti（C0. 3N0. 7） particles range from 0. 1 to 6.0 μm, and they are dispersed evenly in the matrix, which is fine dendritic or cellular crystal. A new kind of phase named Ti（C0.3 N0. 7 ） parti-cles are tightly bonded with α-Fe microstructure, and there is a clean and smooth phase interface between ceramic re-inforcement phase and the matrix.
文摘The Martensite formed at low temperatures in Fe-Ni-Co-Ti alloys is featured as thin plate when the size of γ' dispersively precipitated particles was about 20—50 nm.The interface of martensite plate is not smooth.If the γ'particles are sized less than 5 nm,the thin plate martensite with thermoelastisity may be found at low temperatures,whi greater than 5 nm, intermittent martensite may occur,and the plate martensite increases both in size and quantity with the coarsening of the γ particles.The lenticular or butterfly martensite forms at low tem- peratures until the γ' particles are up to 10—5 nm.
基金Project supported by the National Natural Science Foundation of China(Grant No.11404004)
文摘A novel and simple strategy of morphology-controlled Sr Ti O3（ST） micro-scale particle synthesis by the flux method is reported. Systematic experiments are designed to realize the tunable morphologies of the particles when the flux salt,sintering process, and the precursors are changed. The ST plates can be synthesized by plate-like Bi4Ti3O12（BIT） precursors in Na Cl flux. However, the as-synthesized Bi4Ti3O12 grains transform into reticular particles and finally into rods at higher temperature in Na Cl and KCl compounds. Besides, cubic ST particles are also prepared using different precursors as a comparative experiment. This study provides a strategy for further investigations in designing the morphology-controlled particles and efficient anisotropic materials of perovskite structure such as ferroelectric and photocatalyst.
基金supported by the National Key Research and Development Program of China(2022YFB3708400)the Guangdong Major Project of Basic and Applied Basic Research(2020B0301030006)+1 种基金the Guangdong Academy of Science Fund(2020GDASYL-20200101001)Evaluation Project of Guangdong Provincial Key Laboratory(2023B1212060043).
文摘There are few studies on the preparation of magnesium matrix composites(MMCs)by rapid solidification.This study aims to add minor amounts of Ti particles to AZ91 alloy and prepare AZ91/Ti_(P) MMC ribbon by Melt-Spinning(MS).The effects of Ti particle content on the microstructure and mechanical properties of AZ91/Ti_(P) ribbon were studied by scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),X-ray diffraction(XRD),transmission electron microscopy(TEM),three-dimensional profiling(3D-P)and calculation of supercooling rate.The results show that the grain refinement of AZ91 ribbon prepared by rapid solidification is very significant and the grain refinement is further improved with the increase of Ti particle content;at the same time,the growth of β-Mg_(17)Al_(12) is inhibited,and the interface reaction between Ti and Mg leads to the formation of interfaces around Ti particles.These nano-scale Ti_(3)Al and Al_(3)Ti interface compounds uniformly wrap the Ti particles.It is believed that the addition of Ti particles not only helps to refine the surrounding grains,but also increases the dislocations in the MMC ribbon and forms a good interface,thereby improving the mechanical properties.Compared with AZ91 alloy ribbon,the yield strength and tensile strength of MMC material containing 5 wt.%Ti particles increased by 25.0%and 22.7% respectively.The elongation only decreased by 10.9%.AZ91/5 wt.%Ti_(P) ribbon has a better balance between high strength and high elongation.The analysis shows that the strengthening effect of this mechanical property is mainly attributed to fine grain strengthening,dislocation strengthening and non-basal slip.
基金the Natural Science Foundation of Shanxi Province,China(No.201801D121108)。
文摘SiC/7075 aluminum matrix composites were prepared by a liquid stirring method.The role of Ti facilitating the preparation of SiC/7075 aluminum matrix were studied by means of direct-reading spectrometer,scanning electron microscope,energy dispersive spectrometer,X-ray diffraction and the sessile drop method.The results show that the SiC content in the SiC/7075 composite increases with an increase of Ti addition.The addition of Ti can significantly improve the wettability of SiC/Al system,there is a critical value of above 0.5%of Ti content in improving the wettability of the Al/SiC system at 1173K.The temperature of the"non wetting-wetting"transition for the(Al-2Ti)/SiC system is about 1123K,the contact angle decreases to 88°at 200 seconds and reaches a stable contact angle of 28°at 2100 seconds.
基金financially supported by the National Natural Science Foundation of China(No.51275006)
文摘In this paper, in situ （Ti, Nb）C particle （（Ti, Nb）Cp） reinforced Fe-based composite coatings were produced by laser cladding on the surface of the high carbon steel. The effects of heat input on the microstructure, distribution characteristics of particle, and mechanical properties of the coating were investigated. The results show that （Ti, Nb）C multiple carbide particle is synthesized during solidification of molten pool. The size of particle coarsens gradually, the area ratio of particle increases, and the amount of particles presents a non-monotonous variation with the increase in energy density. The mechanical properties of the coating are improved dramatically compared with those of the substrate, benefiting from its higher hardness and dispersed in situ （Ti, Nb）Cp in it. With the change in heat input, the mechanical performances of the coating vary except the hardness. When energy density is 1 × 10^5 J.mm-2, tensile strength and wear resistance of the coating achieve optimal value due to moderate content and size of the particle in the coating.
基金Item Sponsored by National Natural Science Foundation of China(51275006,51274016)Natural Science Foundation of Beijing of China(2142009)Scientific Plan Item of Beijing Education Committee of China(PXM2015-014204-500170)
文摘（Ti, Nb）C reinforced Fe based laser coatings were prepared with normal and high scanning velocities of the laser beam. The distribution characteristics of reinforced particles in the coatings were investigated. The mechanical properties of coatings were tested. The results showed that the morphologies of the microstructure and the reinforced particle changed dramatically at high solidification rate due to rapid laser processing compared with that prepared by normal processing. Two kinds of particles were observed in the coating. One was （Ti, Nb）C multiple carbide particle with the size of micron and sub micron scales, in which a mass of dislocations were found. Another was nano sized particle including a Fe and （Ti, Nb）C obtained by rapid solidification. The microstructure of the coatings was highly refined and a large number of twin crystals were found in matrix. The resuhs of mechanical properties test revealed that the wear resistance of the coaling was improved by rapid laser processing, compared with that of the coating prepared with normal speeds. The ahove-mentioned conclusion indicated that rapid laser cladding can promote not on ly the processing efficiency but also lhe mechanical properties of the coating.
基金The authors acknowledge the support from the National Natural Foundation of China(Grant No.51974084)Taiyuan University of Science and Technology Scientific Research Initial Funding(Grant Nos.20202039 and 20212052)China Postdoctoral Science Foundation(Grant Nos.2020M673194 and 2020T130329).
文摘In this study,the hot rolled medium manganese steel containing titanium was solution treated at 1,000°C and followed by aging treatment at 500,550,and 600°C.The influence of aging treatment on mechanical properties and wear resistance of medium manganese steel reinforced with Ti(C,N)particles was investigated.It was found that the matrix of medium manganese steel was austenite.The austenite grain size was refined,and Ti(C,N)particles were precipitated after aging treatment.Compared to that of the as-hot rolled sample,the initial hardness of 500°C aged sample increased by 9.5%to 312.86 HV,whose impact energy was more than doubled to 148.5 J.As the aging temperature raised to 600°C,the initial hardness changed slightly.However,the impact energy dropped significantly to 8 J due to the aggregation of Mn at the grain boundaries.In addition,the main wear mechanisms of the samples were fatigue wear and abrasive wear.It was worth noting that 500°C aged sample exhibited the best wear resistance under a 300 N applied load,whose wear loss was just half of the as-hot rolled sample.The relationship between wear loss and mechanical properties indicated that the wear resistance of medium manganese steel was independent of the initial hardness.The large difference in the wear resistance was predominately due to the outstanding work hardening ability of 500°C aged sample,whose strengthening mechanisms were contributed from transformation induced plasticity(TRIP)effect,dislocation strengthening,twinning induced plasticity(TWIP)effect,and precipitation strengthening.
