The microstructure of laser welds of sub-micron particulate-reinforced aluminum matrix composite Al_2O_(3p)/6061Al and the weldability of the material were studied. Experimental results indicated that because of the h...The microstructure of laser welds of sub-micron particulate-reinforced aluminum matrix composite Al_2O_(3p)/6061Al and the weldability of the material were studied. Experimental results indicated that because of the huge specific surface area of the reinforcement, the interfacial reaction between the matrix and the reinforcement was re- strained intenslvely at elevated temperature and pulsed laser beam. The main factor affecting the weldability of the com- posite was the reinforcement segregation in the weld resulting from the push of the liquid/solid interface during the soli- dification of the molten pool. The laser pulse frequency directly affected the reinforcement segregation and the reinfor- cement distribution in the weld, so that the weldability of the composite could be improved by increasing the laser pulse frequency. On the basis of this, a satisfactory welded joint of sub-micron paniculate-reinforced aluminum matrix com- posite Al_2O_(3p)/6061Al was obtained by using appopriate welding parameters.展开更多
Currently, many gratifying signs of progress have been made in magnesium(Mg) matrix composites(MMCs) by virtue of their high mechanical properties both at room and elevated temperatures. Although the commonly used rei...Currently, many gratifying signs of progress have been made in magnesium(Mg) matrix composites(MMCs) by virtue of their high mechanical properties both at room and elevated temperatures. Although the commonly used reinforcements in MMCs are ceramic particles,they often provide improved yield and ultimate stresses by a significant loss in ductility. Therefore, hard metallic phases were introduced as alternative candidates for the manufacturing of MMCs, especially titanium(Ti). It has a high melting point, high Young’s modulus, high plasticity, low level of mutual solubility with Mg matrix, and closer thermal expansion coefficient to that of Mg metal than that of ceramic particles. It is highly preferable to provide both high ultimate stress and ductility in Mg matrix. However, many critical challenges for the fabrication of Ti-reinforced MMCs remain, such as Ti’s homogeneity, low recovery rate, and the optimization of interfacial bonding strength between Mg and Ti, etc. Meanwhile, different fabrication methods have various effects on the microstructures, mechanical properties, and the interfacial strength of Ti-reinforced MMCs. Hence, this review placed emphasis on the microstructural characteristics and mechanical properties of Ti-reinforced MMCs fabricated by different techniques. The influencing factors that govern the strengthening mechanisms were systematically compared and discussed. Future research trends, key issues, and prospects were also proposed to develop Ti-reinforced MMCs.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
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
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
The cenosphere dispersed Ti matrix composite was fabricated by powder metallurgy route, and its wear and corrosion behaviors were investigated. The results show that the microstructure of the fabricated composite cons...The cenosphere dispersed Ti matrix composite was fabricated by powder metallurgy route, and its wear and corrosion behaviors were investigated. The results show that the microstructure of the fabricated composite consists of dispersion of hollow cenosphere particles in a-Ti matrix. The average pore diameter varies from 50 to 150 μm. The presence of porosities is attributed to the damage of cenosphere particles due to the application of load during compaction as well as to the hollow nature of cenospheres. A detailed X-ray diffraction profile of the composites shows the presence of Al2O3, SiO2, TiO2 and α-Ti. The average microhardness of the composite （matrix） varies from HV 1100 to HV 1800 as compared with HV 240 of the as-received substrate. Wear studies show a significant enhancement in wear resistance against hardened steel ball and WC ball compared with that of commercially available Ti-6Al-4V alloy. The wear mechanism was established and presented in detail. The corrosion behavior of the composites in 3.56% NaCl （mass fraction） solution shows that corrosion potential （φcorr） shifts towards nobler direction with improvement in pitting corrosion resistance. However, corrosion rate of the cenosphere dispersed Ti matrix composite increases compared with that of the commercially available Ti-6Al-4V alloy.展开更多
A new steel matrix wear resistant composite reinforced by in situ granular eutectics can be obtained by modifying with a Si-Ce-Ti compound in the steel melt. The result indicates that the in situ granular eutectic is...A new steel matrix wear resistant composite reinforced by in situ granular eutectics can be obtained by modifying with a Si-Ce-Ti compound in the steel melt. The result indicates that the in situ granular eutectic is a pseudo-eutectic of austenite and (Fe,Mn)3C, which is formed between austenite dendrites during solidification due to the segregation of C and Mn impelled by modifying elements. The quantity of in situ granular eutectic reaches up to 8%-12% and its grain size is in the range from 10um to 20um. The austenite steel matrix wear resistant composite reinforced by in situ granular eutectic (abbreviated AGE composite) and austenite-bainite steel mains wear resistant composite reinforced by in situ granular eutectic (abbreviated ABGE composite) are obtained in the as-cast state and by air hardening, respectively. The wear resistance of the AGE and ABGE composites can be more greatly increased than that of their matrix steels under low and medium impact working condition.展开更多
It is showed that there are Ti 3Al, Ti 2Cu and β phase in the interface of Ti/Ti Al composites reinforced with Y 2O 3 Cr composite soft coated Ti fiber, and that interface bonding is intact. Bending strength ...It is showed that there are Ti 3Al, Ti 2Cu and β phase in the interface of Ti/Ti Al composites reinforced with Y 2O 3 Cr composite soft coated Ti fiber, and that interface bonding is intact. Bending strength of the composites can be increased by 26%, to 709 MPa, and bending deflection increased slightly compared with the Ti/Ti Al composites reinforced by Ti fibers coated with Y 2O 3.展开更多
In-situ 5 vol.pct TiB whiskers and TiC particulates reinforced Ti composites were fabricated by blending Ti powderand B4C particulates followed by reactive hot-pressing. The microstructure of the composites was invest...In-situ 5 vol.pct TiB whiskers and TiC particulates reinforced Ti composites were fabricated by blending Ti powderand B4C particulates followed by reactive hot-pressing. The microstructure of the composites was investigated byusing differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscope (TEM)and scanning electron microscope (SEM). The results showed that the reactive temperature between Ti and B4C isabove 570°. Two kinds of reinforcements with different shapes were formed during hot-pressing: TiB short-fiber andequiaxed TiC particles. The interracial bonding between the reinforcements and Ti matrix is perfect. No interracialreaction between reinforcements and Ti matrix was found.展开更多
In SiC（f）/Ti-6Al-4V composites, the microstructure of the matrix close to the fiber was different from that of the fiber-less material. Microstructure observations show that a layer of fine grains was located adjace...In SiC（f）/Ti-6Al-4V composites, the microstructure of the matrix close to the fiber was different from that of the fiber-less material. Microstructure observations show that a layer of fine grains was located adjacent to the fiber, and more dislocations and faults were found in this region. Higher recrystallization nucleation rate due to the undeformed SiC fiber and thermal residual stress induced during cooling from the fabrication temperature caused the microstructural changes of the matrix. Hardness measurement indicates that the matrix in the fiber neighborhood was strengthened, and the strengthening effect decreased with distance away from the fiber.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
为了在大气条件下利用 Fe- Ti- C熔体中 Ti C的合成反应制备原位 (in situ) Ti CP/Fe复合材料 ,研究了三种覆盖剂对熔体中 Ti元素氧化烧损率的影响 ,并分析了所得复合材料的组织和性能。结果表明 :采用所开发的混合盐型覆盖剂能在大气...为了在大气条件下利用 Fe- Ti- C熔体中 Ti C的合成反应制备原位 (in situ) Ti CP/Fe复合材料 ,研究了三种覆盖剂对熔体中 Ti元素氧化烧损率的影响 ,并分析了所得复合材料的组织和性能。结果表明 :采用所开发的混合盐型覆盖剂能在大气条件下制备出原位 Ti CP/Fe复合材料 ,且原位合成的 Ti C颗粒尺寸细小、分布均匀 ,从而使制备的复合材料特别是经淬火处理后的复合材料具有较高的力学性能。展开更多
基金This project is financially supported by the National Nature Science Fund (59785016) and the Opening Fund ([2000]002) of the N
文摘The microstructure of laser welds of sub-micron particulate-reinforced aluminum matrix composite Al_2O_(3p)/6061Al and the weldability of the material were studied. Experimental results indicated that because of the huge specific surface area of the reinforcement, the interfacial reaction between the matrix and the reinforcement was re- strained intenslvely at elevated temperature and pulsed laser beam. The main factor affecting the weldability of the com- posite was the reinforcement segregation in the weld resulting from the push of the liquid/solid interface during the soli- dification of the molten pool. The laser pulse frequency directly affected the reinforcement segregation and the reinfor- cement distribution in the weld, so that the weldability of the composite could be improved by increasing the laser pulse frequency. On the basis of this, a satisfactory welded joint of sub-micron paniculate-reinforced aluminum matrix com- posite Al_2O_(3p)/6061Al was obtained by using appopriate welding parameters.
基金National Natural Science Foundation of China (52101123, 52171103)Guangdong Major Project of Basic and Applied Basic Research (2020B0301030006) for the support。
文摘Currently, many gratifying signs of progress have been made in magnesium(Mg) matrix composites(MMCs) by virtue of their high mechanical properties both at room and elevated temperatures. Although the commonly used reinforcements in MMCs are ceramic particles,they often provide improved yield and ultimate stresses by a significant loss in ductility. Therefore, hard metallic phases were introduced as alternative candidates for the manufacturing of MMCs, especially titanium(Ti). It has a high melting point, high Young’s modulus, high plasticity, low level of mutual solubility with Mg matrix, and closer thermal expansion coefficient to that of Mg metal than that of ceramic particles. It is highly preferable to provide both high ultimate stress and ductility in Mg matrix. However, many critical challenges for the fabrication of Ti-reinforced MMCs remain, such as Ti’s homogeneity, low recovery rate, and the optimization of interfacial bonding strength between Mg and Ti, etc. Meanwhile, different fabrication methods have various effects on the microstructures, mechanical properties, and the interfacial strength of Ti-reinforced MMCs. Hence, this review placed emphasis on the microstructural characteristics and mechanical properties of Ti-reinforced MMCs fabricated by different techniques. The influencing factors that govern the strengthening mechanisms were systematically compared and discussed. Future research trends, key issues, and prospects were also proposed to develop Ti-reinforced MMCs.
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Financial supports from various funding agencies Tata Steel, Jamshedpur, Department of Science and Technology, New Delhi, Council of Scientific and Industrial Research, New Delhi and Board of Research on Nuclear Science, Bombay for the present study are gratefully acknowledged
文摘The cenosphere dispersed Ti matrix composite was fabricated by powder metallurgy route, and its wear and corrosion behaviors were investigated. The results show that the microstructure of the fabricated composite consists of dispersion of hollow cenosphere particles in a-Ti matrix. The average pore diameter varies from 50 to 150 μm. The presence of porosities is attributed to the damage of cenosphere particles due to the application of load during compaction as well as to the hollow nature of cenospheres. A detailed X-ray diffraction profile of the composites shows the presence of Al2O3, SiO2, TiO2 and α-Ti. The average microhardness of the composite （matrix） varies from HV 1100 to HV 1800 as compared with HV 240 of the as-received substrate. Wear studies show a significant enhancement in wear resistance against hardened steel ball and WC ball compared with that of commercially available Ti-6Al-4V alloy. The wear mechanism was established and presented in detail. The corrosion behavior of the composites in 3.56% NaCl （mass fraction） solution shows that corrosion potential （φcorr） shifts towards nobler direction with improvement in pitting corrosion resistance. However, corrosion rate of the cenosphere dispersed Ti matrix composite increases compared with that of the commercially available Ti-6Al-4V alloy.
基金Acknowledgements - This project was supported by the National Natural Science Foundation of China (Grant No.50001008).
文摘A new steel matrix wear resistant composite reinforced by in situ granular eutectics can be obtained by modifying with a Si-Ce-Ti compound in the steel melt. The result indicates that the in situ granular eutectic is a pseudo-eutectic of austenite and (Fe,Mn)3C, which is formed between austenite dendrites during solidification due to the segregation of C and Mn impelled by modifying elements. The quantity of in situ granular eutectic reaches up to 8%-12% and its grain size is in the range from 10um to 20um. The austenite steel matrix wear resistant composite reinforced by in situ granular eutectic (abbreviated AGE composite) and austenite-bainite steel mains wear resistant composite reinforced by in situ granular eutectic (abbreviated ABGE composite) are obtained in the as-cast state and by air hardening, respectively. The wear resistance of the AGE and ABGE composites can be more greatly increased than that of their matrix steels under low and medium impact working condition.
文摘It is showed that there are Ti 3Al, Ti 2Cu and β phase in the interface of Ti/Ti Al composites reinforced with Y 2O 3 Cr composite soft coated Ti fiber, and that interface bonding is intact. Bending strength of the composites can be increased by 26%, to 709 MPa, and bending deflection increased slightly compared with the Ti/Ti Al composites reinforced by Ti fibers coated with Y 2O 3.
文摘In-situ 5 vol.pct TiB whiskers and TiC particulates reinforced Ti composites were fabricated by blending Ti powderand B4C particulates followed by reactive hot-pressing. The microstructure of the composites was investigated byusing differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscope (TEM)and scanning electron microscope (SEM). The results showed that the reactive temperature between Ti and B4C isabove 570°. Two kinds of reinforcements with different shapes were formed during hot-pressing: TiB short-fiber andequiaxed TiC particles. The interracial bonding between the reinforcements and Ti matrix is perfect. No interracialreaction between reinforcements and Ti matrix was found.
文摘In SiC（f）/Ti-6Al-4V composites, the microstructure of the matrix close to the fiber was different from that of the fiber-less material. Microstructure observations show that a layer of fine grains was located adjacent to the fiber, and more dislocations and faults were found in this region. Higher recrystallization nucleation rate due to the undeformed SiC fiber and thermal residual stress induced during cooling from the fabrication temperature caused the microstructural changes of the matrix. Hardness measurement indicates that the matrix in the fiber neighborhood was strengthened, and the strengthening effect decreased with distance away from the fiber.
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.
文摘为了在大气条件下利用 Fe- Ti- C熔体中 Ti C的合成反应制备原位 (in situ) Ti CP/Fe复合材料 ,研究了三种覆盖剂对熔体中 Ti元素氧化烧损率的影响 ,并分析了所得复合材料的组织和性能。结果表明 :采用所开发的混合盐型覆盖剂能在大气条件下制备出原位 Ti CP/Fe复合材料 ,且原位合成的 Ti C颗粒尺寸细小、分布均匀 ,从而使制备的复合材料特别是经淬火处理后的复合材料具有较高的力学性能。
