A Y2O3 particle enhanced Ni/TiC composite coating was fabricated in-situ on a TC4 Ti alloy by laser surface cladding.The phase component,microstructure,composition distribution and properties of the composite layer we...A Y2O3 particle enhanced Ni/TiC composite coating was fabricated in-situ on a TC4 Ti alloy by laser surface cladding.The phase component,microstructure,composition distribution and properties of the composite layer were investigated.The composite layer has graded microstructures and compositions,due to the fast melting followed by rapid solidification and cooling during laser cladding.The TiC powders are completely dissolved into the melted layer during melting and segregated as fine dendrites when solidified.The size of TiC dendrites decreases with increasing depth.Y2O3 fine particles distribute in the whole clad layer.The Y2O3 particle enhanced Ni/TiC composite layer has a quite uniform hardness along depth with a maximum value of HV1380,which is 4 times higher than the initial hardness.The wear resistance of the Ti alloy is significantly improved after laser cladding due to the high hardness of the composite coating.展开更多
Ti3AlC2/TiC-Al2O3 composite was synthesized by a combustion reaction in TiO2-Al-C system. The effect of the compositions in raw materials on the products was investigated. Ti3AlC2/TiC-Al2O3 composite was obtained at t...Ti3AlC2/TiC-Al2O3 composite was synthesized by a combustion reaction in TiO2-Al-C system. The effect of the compositions in raw materials on the products was investigated. Ti3AlC2/TiC-Al2O3 composite was obtained at the molar ratio of TiO2：Al：C=3.0：5.0～5.1：1.8～2.0. The reaction path for the 3TiO2-5Al- 2C system was proposed. Al3Ti, Ti203, TiO, and 6-Al2O3 are found to be transitional phases. Finally, Ti3AlC2/TiC-Al2O3 composite forms at～900℃ of furnace temperature. The measured Vickers hardness, fracture toughness, and flexural strength of the nearly dense sample from 3TiO2-5Al-2C are 13.3±1.1 GPa, 5.8±0.3 MPa.m^1/2, and 466±39 MPa, respectively.展开更多
TiC/Ni_3Al composites have been prepared using upward infiltration method. The densification was performed by both Ni_3Al melt filling and TiC sintering during the infiltration. The dissolution of TiC in liquid Ni_3A...TiC/Ni_3Al composites have been prepared using upward infiltration method. The densification was performed by both Ni_3Al melt filling and TiC sintering during the infiltration. The dissolution of TiC in liquid Ni_3Al has been evidenced by finding Ni_3(Al,Ti)C after fast cooling in the TiC/Ni_3Al composites. The dissolution may be responsible for the infiltration and sintering. Compared with downward infiltration, the upward infiltration brought about higher strength and fracture toughness and shorter infiltration time. TiC/20 vol. pct Ni_3Al composite processed by upward infiltration had a flexural strength of 1476 MPa with a statistic Weibull modulus of 20.2 and a fracture toughness of 20.4 MPa . Better mechanical properties may be attributed to melt unidirectional movement in upward infiltration.展开更多
The thermal shock fatigue behaviors of pure hot-pressed alumina and 30 wt.% TiC/Al2O3 composites were studied. The effect of TiC and Al2O3 starting particle size on the mechanical properties of the composites was disc...The thermal shock fatigue behaviors of pure hot-pressed alumina and 30 wt.% TiC/Al2O3 composites were studied. The effect of TiC and Al2O3 starting particle size on the mechanical properties of the composites was discussed. Indentation-quench test was conducted to evaluate the effect of thermal fatigue temperature difference （ΔT） and number of thermal cycles （Ⅳ） on fatigue crack growth （Δa）. The mechanical properties and thermal fatigue resistance of TiC/Al203 composites are remarkably improved by the addition of TiC. The thermal shock fatigue of monolithic alumina and TiC/Al2O3 composites is due to a ＂true＂ cycling effect （thermal fatigue）. Crack deflection and bridging are the predominant reasons for the improvement of thermal shock fatigue resistance of the composites.展开更多
Cold-rolled Ti/Al laminated composites were annealed at 525−625℃for 0−128 h,and the interfacial microstructure evolution was investigated.The results indicate that only the TiAl_(3) phase was formed at the Ti/Al inte...Cold-rolled Ti/Al laminated composites were annealed at 525−625℃for 0−128 h,and the interfacial microstructure evolution was investigated.The results indicate that only the TiAl_(3) phase was formed at the Ti/Al interface;most of TiAl_(3) grains were fine equiaxed with average sizes ranging from hundreds of nanometers to several microns and the TiAl_(3) grain size increased with increasing annealing time and/or temperature,but the effect of annealing temperature on the TiAl_(3) grain size was far greater than that of annealing time.The growth of the TiAl_(3) phase consisted of two stages.The initial stage was governed by chemical reaction with a reaction activation energy of 195.75 kJ/mol,and the reaction rate constant of the TiAl_(3) phase was larger as the Ti/Al interface was bonded with fresh surfaces.At the second stage,the growth was governed by diffusion,the diffusion activation energy was 33.69 kJ/mol,and the diffusion growth rate constant of the TiAl_(3) phase was mainly determined by the grain boundary diffusion owing to the smaller TiAl_(3) grain size.展开更多
Hot compression behavior of TiC–Al2O3/Al composites was studied using the Gleeble-1500 system at a temperature range of 300–550 °C and at strain rate range of 0.01–10.00 s-1. The associated structural changes ...Hot compression behavior of TiC–Al2O3/Al composites was studied using the Gleeble-1500 system at a temperature range of 300–550 °C and at strain rate range of 0.01–10.00 s-1. The associated structural changes were studied by TEM observations. The results show that stress level decreases with deformation temperature increasing and strain rate decreasing, which can be represented by a Zener–Hollomon parameter in an exponent-type equation with hot deformation activation energy Q of 172.56 kJ·mol-1.Dynamic recovery occurs easily when strain rates are less than 10.00 s-1. Dynamic recrystallization can occur at strain rate of 10.00 s-1.展开更多
Ceramic tapes, containing Al2O3-25 wt pct TiB2(B) and Al2O3-25 wt pct nano-TiC (c), have been obtained by tape casting process. Numerous tapes (about 60～80 tapes) were prepared by stacking in turn the composition (B)...Ceramic tapes, containing Al2O3-25 wt pct TiB2(B) and Al2O3-25 wt pct nano-TiC (c), have been obtained by tape casting process. Numerous tapes (about 60～80 tapes) were prepared by stacking in turn the composition (B) and (C), laminating under 10 MPa pressure, eliminating the solvent and burning out the polymer additives. The final green bodies were hot pressed at 1750℃ and 30 MPa. The composite has a bending strength of 568 MPa and a fracture toughness of 5.8 M Pa·m1/2. SEM analysis exhibits that Al2O3 particle growth was inhibited by TiC particles in C. but TiB2 particles could not hinder Al2O3 growth in B. The curves of GTA indicates that all organic additives could be removed completely above 600℃展开更多
Al-Al3Ti composites were prepared by a direct reaction method, in which Al3Ti was formed by the reaction of Ti and Al in aluminum alloy melt. The morphology of Al3Ti changes apparently from the fine particle, needle-l...Al-Al3Ti composites were prepared by a direct reaction method, in which Al3Ti was formed by the reaction of Ti and Al in aluminum alloy melt. The morphology of Al3Ti changes apparently from the fine particle, needle-like to large block with the increase of Al3Ti content. The addition of magnesium can markedly change the morphology of Al3Ti and reduce their size. Short rod-like Al3Ti was formed and homogeneous distribution was obtained with the addition of 3 wt.% Mg. The effect of Al3Ti and Mg on the microstructure of Al-Al3Ti composites and the mechanism were also discussed.展开更多
An Al-based composite reinforced with core–shell-structured Ti/Al_3Ti was fabricated through a powder metallurgy route followed by hot extrusion and was found to exhibit promising mechanical properties. The ultimate ...An Al-based composite reinforced with core–shell-structured Ti/Al_3Ti was fabricated through a powder metallurgy route followed by hot extrusion and was found to exhibit promising mechanical properties. The ultimate tensile strength and elongation of the composite sintered at 620°C for 5 h and extruded at a mass ratio of 12.75:1 reached 304 MPa and 14%, respectively, and its compressive deformation reached 60%. The promising mechanical properties are due to the core–shell-structured reinforcement, which is mainly composed of Al_3Ti and Ti and is bonded strongly with the Al matrix, and to the reduced crack sensitivity of Al_3Ti. The refined grains after hot extrusion also contribute to the mechanical properties of this composite. The mechanical properties might be further improved through regulating the relative thickness of Al–Ti intermetallics and Ti metal layers by adjusting the sintering time and the subsequent extrusion process.展开更多
Two-dimensional(2D)Ti3C2Tx MXene is an attractive additive not only used in base oil due to its low friction coefficient,but also used in composites due to its high aspect ratio and rich surface functional groups.So f...Two-dimensional(2D)Ti3C2Tx MXene is an attractive additive not only used in base oil due to its low friction coefficient,but also used in composites due to its high aspect ratio and rich surface functional groups.So far there has been intense research into polymer matrix composites reinforced with Ti3C2Tx,Here we report on the use of 2D Ti3C2Tx to enhance the mechanical and frictional properties of Al matrix composites.Ti3C2Tx/Al composites were designed and prepared by pre s sureless sintering followed by hot extrusion technique.The prepared composites exhibit a homogeneous distribution of Ti3C2Tx.The Vickers hardness and the tensile strength continuously increase with increasing Ti3C2Tx content.A hardness of 0.52 GPa and a tensile strength of 148 MPa were achieved in the 3 wt%Ti3C2Tx/Al composite.The frictional properties of pure Al and the Ti3C2Tx/Al composite were comparably studied under dry sliding.A low friction coefficient of 0.2,twice lower than that of pure Al,was achieved in the 3 wt%Ti3C2Tx/Al composite.Ti3C2Tx acting as a solid lubricant reduces the abrasive wear in the composite,improving the frictional properties of Al matrix composites.展开更多
XD TM method was used to prepare titanium aluminide(Ti 3Al) matrix composites. The phase constitution and the as cast microstructure of Ti 25Al alloy with different carbon contents have been investigated using XRD and...XD TM method was used to prepare titanium aluminide(Ti 3Al) matrix composites. The phase constitution and the as cast microstructure of Ti 25Al alloy with different carbon contents have been investigated using XRD and SEM. Microhardness and elastic modulus of the matrix and reinforcements were tested by mechanical property microprobe. In Ti 25Al 0.5C alloy, blocky Ti 3AlC and lath Ti 3AlC were in situ formed as reinforcement, and homogeneously distributed in the matrix. The microhardness and elastic modulus of blocky Ti 3AlC are 14.2 GPa and 281.3 GPa respectively, higher than those of the lath Ti 3AlC about 3 GPa and 60 GPa respectively. When C content is more than 0.5%, dendritic TiC and Ti 3AlC were formed as reinforcement in a core structure, where the TiC core is coated with Ti 3AlC phase. The microhardness and elastic modulus of the reinforcement decrease with increasing distance from the center of the reinforcement and matrix. The maximum microhardness and modulus of TiC and Ti 3AlC are 22.8 GPa, 302.7 GPa and 20.2 GPa, 313.5 GPa, respectively.展开更多
A novel technique for fabricating TiB_2/Al composites in molten aluminum was introduced. The formation mechanism of brittleAl,Ti particulates up to 30 m in size produced in the composites was studied and a method of e...A novel technique for fabricating TiB_2/Al composites in molten aluminum was introduced. The formation mechanism of brittleAl,Ti particulates up to 30 m in size produced in the composites was studied and a method of eliminating them was proposed. The resultsshow that (l) the brittle Al,Ti particulates are always present in the composites when the molar ratio of Ti to B 'T,:nB is l:2; and (2) theformation of the brittle Al,Ti phase can be avoided entirely from the final product by using a proper 'T,:nB of l:4 in the Ti-B-Al preforms.In the former case, the tensile elongation of the composite is only 4%, much lower than the value of pure aluminum (20%). In the latercase, the tensile elongation of this composite is 10%, higher than the value of the composite with a lot ofAl,Ti (4%), whereas the ultimatetensile stfength of the former is nearly that of the later.展开更多
Ti/Al 2O 3 composite with improved mechanical properties was synthesized by th e spark plasma sintering. The effect of Nb on the microstructure of the composit e was analyzed by TEM, SEM and so on. The experimental ...Ti/Al 2O 3 composite with improved mechanical properties was synthesized by th e spark plasma sintering. The effect of Nb on the microstructure of the composit e was analyzed by TEM, SEM and so on. The experimental results indicate that the bending strength, fracture toughness, micro-hardness and relative density of t he composite are 897.29MPa, 17.38MPa·m 1/2, 17.13GPa and 99.24% respec tively when adding 1.5vol%Nb. The bending strength is improved by reason of form ing dislocation ring and transfering fracture mode from intergranular to mixture fracture of intergranular and transgranular. The crack propagating is mainly th e deflection bridging. It indicates a reduction of crack driving force and an in crease in crack growth resistance,which results in toughness enhanced.展开更多
The influence of Mo on the microstructure,bending strength and HV of Ti/Al 2O 3 composite was studied,and the influence mechanism was analyzed.The results indicate that after the addition of Mo,the composite organiz...The influence of Mo on the microstructure,bending strength and HV of Ti/Al 2O 3 composite was studied,and the influence mechanism was analyzed.The results indicate that after the addition of Mo,the composite organization is finer and phases distribution is better-proportioned which make the microstructure denser,the bending strength and HV of composite are also increased to a degree.But the bending strength increases first then decreases with the increasing of Mo content,so the appropriate Mo content for the Ti/Al 2O 3 composite is to be further confirmed.展开更多
基金Projects(51101096,51002093)supported by the National Natural Science Foundation of ChinaProject(1052nm05000)supported by Special Foundation of the Shanghai Science and Technology Commission for Nano-Materials ResearchProject(J51042)supported by Leading Academic Discipline Project of the Shanghai Education Commission,China
文摘A Y2O3 particle enhanced Ni/TiC composite coating was fabricated in-situ on a TC4 Ti alloy by laser surface cladding.The phase component,microstructure,composition distribution and properties of the composite layer were investigated.The composite layer has graded microstructures and compositions,due to the fast melting followed by rapid solidification and cooling during laser cladding.The TiC powders are completely dissolved into the melted layer during melting and segregated as fine dendrites when solidified.The size of TiC dendrites decreases with increasing depth.Y2O3 fine particles distribute in the whole clad layer.The Y2O3 particle enhanced Ni/TiC composite layer has a quite uniform hardness along depth with a maximum value of HV1380,which is 4 times higher than the initial hardness.The wear resistance of the Ti alloy is significantly improved after laser cladding due to the high hardness of the composite coating.
文摘Ti3AlC2/TiC-Al2O3 composite was synthesized by a combustion reaction in TiO2-Al-C system. The effect of the compositions in raw materials on the products was investigated. Ti3AlC2/TiC-Al2O3 composite was obtained at the molar ratio of TiO2：Al：C=3.0：5.0～5.1：1.8～2.0. The reaction path for the 3TiO2-5Al- 2C system was proposed. Al3Ti, Ti203, TiO, and 6-Al2O3 are found to be transitional phases. Finally, Ti3AlC2/TiC-Al2O3 composite forms at～900℃ of furnace temperature. The measured Vickers hardness, fracture toughness, and flexural strength of the nearly dense sample from 3TiO2-5Al-2C are 13.3±1.1 GPa, 5.8±0.3 MPa.m^1/2, and 466±39 MPa, respectively.
文摘TiC/Ni_3Al composites have been prepared using upward infiltration method. The densification was performed by both Ni_3Al melt filling and TiC sintering during the infiltration. The dissolution of TiC in liquid Ni_3Al has been evidenced by finding Ni_3(Al,Ti)C after fast cooling in the TiC/Ni_3Al composites. The dissolution may be responsible for the infiltration and sintering. Compared with downward infiltration, the upward infiltration brought about higher strength and fracture toughness and shorter infiltration time. TiC/20 vol. pct Ni_3Al composite processed by upward infiltration had a flexural strength of 1476 MPa with a statistic Weibull modulus of 20.2 and a fracture toughness of 20.4 MPa . Better mechanical properties may be attributed to melt unidirectional movement in upward infiltration.
文摘The thermal shock fatigue behaviors of pure hot-pressed alumina and 30 wt.% TiC/Al2O3 composites were studied. The effect of TiC and Al2O3 starting particle size on the mechanical properties of the composites was discussed. Indentation-quench test was conducted to evaluate the effect of thermal fatigue temperature difference （ΔT） and number of thermal cycles （Ⅳ） on fatigue crack growth （Δa）. The mechanical properties and thermal fatigue resistance of TiC/Al203 composites are remarkably improved by the addition of TiC. The thermal shock fatigue of monolithic alumina and TiC/Al2O3 composites is due to a ＂true＂ cycling effect （thermal fatigue）. Crack deflection and bridging are the predominant reasons for the improvement of thermal shock fatigue resistance of the composites.
基金the financial supports from the S&T Program of Hebei Province,China(No.20373901D)the National Natural Science Foundation of China(Nos.51807047,51804095)+2 种基金the National Science Foundation of Hebei Province,China(No.E2019402433)the Youth Top Talents Science and Technology Research Project of Hebei Province University,China(No.BJ2019003)the Research and Development Project of Science and Technology of Handan City,China(No.19422111008-19).
文摘Cold-rolled Ti/Al laminated composites were annealed at 525−625℃for 0−128 h,and the interfacial microstructure evolution was investigated.The results indicate that only the TiAl_(3) phase was formed at the Ti/Al interface;most of TiAl_(3) grains were fine equiaxed with average sizes ranging from hundreds of nanometers to several microns and the TiAl_(3) grain size increased with increasing annealing time and/or temperature,but the effect of annealing temperature on the TiAl_(3) grain size was far greater than that of annealing time.The growth of the TiAl_(3) phase consisted of two stages.The initial stage was governed by chemical reaction with a reaction activation energy of 195.75 kJ/mol,and the reaction rate constant of the TiAl_(3) phase was larger as the Ti/Al interface was bonded with fresh surfaces.At the second stage,the growth was governed by diffusion,the diffusion activation energy was 33.69 kJ/mol,and the diffusion growth rate constant of the TiAl_(3) phase was mainly determined by the grain boundary diffusion owing to the smaller TiAl_(3) grain size.
基金financially supported by the Inner Mongolia Science and Technology Reward Foundation(No.20101707)the Inner Mongolia Natural Science Foundation(No.2013MS0804)+1 种基金the Inner Mongolia High School Scientific Research Foundation(No.NJZZ14056)the Inner Mongolia University of Technology Foundation(No.ZD20120015)
文摘Hot compression behavior of TiC–Al2O3/Al composites was studied using the Gleeble-1500 system at a temperature range of 300–550 °C and at strain rate range of 0.01–10.00 s-1. The associated structural changes were studied by TEM observations. The results show that stress level decreases with deformation temperature increasing and strain rate decreasing, which can be represented by a Zener–Hollomon parameter in an exponent-type equation with hot deformation activation energy Q of 172.56 kJ·mol-1.Dynamic recovery occurs easily when strain rates are less than 10.00 s-1. Dynamic recrystallization can occur at strain rate of 10.00 s-1.
文摘Ceramic tapes, containing Al2O3-25 wt pct TiB2(B) and Al2O3-25 wt pct nano-TiC (c), have been obtained by tape casting process. Numerous tapes (about 60～80 tapes) were prepared by stacking in turn the composition (B) and (C), laminating under 10 MPa pressure, eliminating the solvent and burning out the polymer additives. The final green bodies were hot pressed at 1750℃ and 30 MPa. The composite has a bending strength of 568 MPa and a fracture toughness of 5.8 M Pa·m1/2. SEM analysis exhibits that Al2O3 particle growth was inhibited by TiC particles in C. but TiB2 particles could not hinder Al2O3 growth in B. The curves of GTA indicates that all organic additives could be removed completely above 600℃
文摘Al-Al3Ti composites were prepared by a direct reaction method, in which Al3Ti was formed by the reaction of Ti and Al in aluminum alloy melt. The morphology of Al3Ti changes apparently from the fine particle, needle-like to large block with the increase of Al3Ti content. The addition of magnesium can markedly change the morphology of Al3Ti and reduce their size. Short rod-like Al3Ti was formed and homogeneous distribution was obtained with the addition of 3 wt.% Mg. The effect of Al3Ti and Mg on the microstructure of Al-Al3Ti composites and the mechanism were also discussed.
基金financially supported by the Science and Technology Plan Item of Liaoning Province (No.201601174)the National Natural Science Foundation of China (No.51371121)
文摘An Al-based composite reinforced with core–shell-structured Ti/Al_3Ti was fabricated through a powder metallurgy route followed by hot extrusion and was found to exhibit promising mechanical properties. The ultimate tensile strength and elongation of the composite sintered at 620°C for 5 h and extruded at a mass ratio of 12.75:1 reached 304 MPa and 14%, respectively, and its compressive deformation reached 60%. The promising mechanical properties are due to the core–shell-structured reinforcement, which is mainly composed of Al_3Ti and Ti and is bonded strongly with the Al matrix, and to the reduced crack sensitivity of Al_3Ti. The refined grains after hot extrusion also contribute to the mechanical properties of this composite. The mechanical properties might be further improved through regulating the relative thickness of Al–Ti intermetallics and Ti metal layers by adjusting the sintering time and the subsequent extrusion process.
基金supported by the National Natural Science Foundation of China(No.51772020)Beijing Natural Science Foundation(No.2182058)+1 种基金Beijing Government Funds for the Constructive Project of Central UniversitiesEquipment Development Department of the National Military Commission Foundation of China(No.JZX7Y20190262063601)。
文摘Two-dimensional(2D)Ti3C2Tx MXene is an attractive additive not only used in base oil due to its low friction coefficient,but also used in composites due to its high aspect ratio and rich surface functional groups.So far there has been intense research into polymer matrix composites reinforced with Ti3C2Tx,Here we report on the use of 2D Ti3C2Tx to enhance the mechanical and frictional properties of Al matrix composites.Ti3C2Tx/Al composites were designed and prepared by pre s sureless sintering followed by hot extrusion technique.The prepared composites exhibit a homogeneous distribution of Ti3C2Tx.The Vickers hardness and the tensile strength continuously increase with increasing Ti3C2Tx content.A hardness of 0.52 GPa and a tensile strength of 148 MPa were achieved in the 3 wt%Ti3C2Tx/Al composite.The frictional properties of pure Al and the Ti3C2Tx/Al composite were comparably studied under dry sliding.A low friction coefficient of 0.2,twice lower than that of pure Al,was achieved in the 3 wt%Ti3C2Tx/Al composite.Ti3C2Tx acting as a solid lubricant reduces the abrasive wear in the composite,improving the frictional properties of Al matrix composites.
文摘XD TM method was used to prepare titanium aluminide(Ti 3Al) matrix composites. The phase constitution and the as cast microstructure of Ti 25Al alloy with different carbon contents have been investigated using XRD and SEM. Microhardness and elastic modulus of the matrix and reinforcements were tested by mechanical property microprobe. In Ti 25Al 0.5C alloy, blocky Ti 3AlC and lath Ti 3AlC were in situ formed as reinforcement, and homogeneously distributed in the matrix. The microhardness and elastic modulus of blocky Ti 3AlC are 14.2 GPa and 281.3 GPa respectively, higher than those of the lath Ti 3AlC about 3 GPa and 60 GPa respectively. When C content is more than 0.5%, dendritic TiC and Ti 3AlC were formed as reinforcement in a core structure, where the TiC core is coated with Ti 3AlC phase. The microhardness and elastic modulus of the reinforcement decrease with increasing distance from the center of the reinforcement and matrix. The maximum microhardness and modulus of TiC and Ti 3AlC are 22.8 GPa, 302.7 GPa and 20.2 GPa, 313.5 GPa, respectively.
文摘A novel technique for fabricating TiB_2/Al composites in molten aluminum was introduced. The formation mechanism of brittleAl,Ti particulates up to 30 m in size produced in the composites was studied and a method of eliminating them was proposed. The resultsshow that (l) the brittle Al,Ti particulates are always present in the composites when the molar ratio of Ti to B 'T,:nB is l:2; and (2) theformation of the brittle Al,Ti phase can be avoided entirely from the final product by using a proper 'T,:nB of l:4 in the Ti-B-Al preforms.In the former case, the tensile elongation of the composite is only 4%, much lower than the value of pure aluminum (20%). In the latercase, the tensile elongation of this composite is 10%, higher than the value of the composite with a lot ofAl,Ti (4%), whereas the ultimatetensile stfength of the former is nearly that of the later.
基金Funded by the National Natural Science Foundation of China (No. 50232020) and the Natural Science Foundation of Shandong Province(No.2002F21)
文摘Ti/Al 2O 3 composite with improved mechanical properties was synthesized by th e spark plasma sintering. The effect of Nb on the microstructure of the composit e was analyzed by TEM, SEM and so on. The experimental results indicate that the bending strength, fracture toughness, micro-hardness and relative density of t he composite are 897.29MPa, 17.38MPa·m 1/2, 17.13GPa and 99.24% respec tively when adding 1.5vol%Nb. The bending strength is improved by reason of form ing dislocation ring and transfering fracture mode from intergranular to mixture fracture of intergranular and transgranular. The crack propagating is mainly th e deflection bridging. It indicates a reduction of crack driving force and an in crease in crack growth resistance,which results in toughness enhanced.
文摘The influence of Mo on the microstructure,bending strength and HV of Ti/Al 2O 3 composite was studied,and the influence mechanism was analyzed.The results indicate that after the addition of Mo,the composite organization is finer and phases distribution is better-proportioned which make the microstructure denser,the bending strength and HV of composite are also increased to a degree.But the bending strength increases first then decreases with the increasing of Mo content,so the appropriate Mo content for the Ti/Al 2O 3 composite is to be further confirmed.
