The partially stabilized ZrO2 (PSZ) particles were introduced into TiB2 ceramics to improve its density and mechanical properties. The results show that the addition of PSZ is very effective not only in bettering the ...The partially stabilized ZrO2 (PSZ) particles were introduced into TiB2 ceramics to improve its density and mechanical properties. The results show that the addition of PSZ is very effective not only in bettering the sinterability but also in enhancing the flexural strength and fracture toughness of TiB2.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
Ni-50at.%A1 matrix composites containing 0 to 20v.% TiB_(2) particles have been successfully fabricated by HPES technique. The results show that the Vickers hardness at room temperature and the compressive yield stren...Ni-50at.%A1 matrix composites containing 0 to 20v.% TiB_(2) particles have been successfully fabricated by HPES technique. The results show that the Vickers hardness at room temperature and the compressive yield strength from room temperature to 1000℃ of the composites increase with increasing volume fraction of the strengthening phase. Especially, the yield strength of NiAl-20TiB_(2) was approximately twice as high as that of unreinforced NiAl. The ductility of the composites at room temperature is also superior to the monolithic NiAl.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
TiB_(2p)/Cu composites with high reinforcement content(φ_(p)=50%,58%and 65%)for electronic packaging applications were fabricated by squeeze casting technology.The microstructures and thermo-physical properties of th...TiB_(2p)/Cu composites with high reinforcement content(φ_(p)=50%,58%and 65%)for electronic packaging applications were fabricated by squeeze casting technology.The microstructures and thermo-physical properties of the TiB_(2p)/Cu composites were investigated.The results show that TiB2 particles are homogeneous and distribute uniformly,and the TiB2-Cu interfaces are clean and free-from interfacial reaction products and amorphous layers,the densifications of the TiB_(2p)/Cu composites are higher than 98.2%. The mean linear coefficients of thermal expansion at 20-100℃for TiB_(2p)/Cu composites range from 8.3×10^(-6)to 10.8×10^(-6)/K and decrease with increasing volume fraction of TiB2.The experimental coefficients of thermal expansion agree well with the predicted values based on Turner’s model.The thermal conductivities of TiB_(2p)/Cu composites range from 167.3 to 215.4 W/(m·K),decreasing with increasing volume fraction TiB2.展开更多
The microstructure and mechanical properties of TiB_2 /B_4C composites have been investi- gated.It was found that both the strength and hardness for TiB_2 greatly increase with the ad- dition of 20 to 30 wt-% B_4C,and...The microstructure and mechanical properties of TiB_2 /B_4C composites have been investi- gated.It was found that both the strength and hardness for TiB_2 greatly increase with the ad- dition of 20 to 30 wt-% B_4C,and the fracture toughness K_(IC) value remaines on the original high level.The flexure strength,Vicker's hardness and fracture toughness are 782 MPa,26.2 GPa and 7.2 MPam^(1/2),respectively,for the TiB_2-30 wt-% B_4C composite,compared to 450 MPa,21 GPa and 7.0 MPam^(1/2) for monolithic TiB_2.The toughening and strengthening mechanisms,have also been discussed.展开更多
14% and 20% (volume fraction) TiB2p/6061Al composites were fabricated by pressure infiltration method, and then were extruded. The microstructure and properties of TiB2p/Al composites before and after extrusion were s...14% and 20% (volume fraction) TiB2p/6061Al composites were fabricated by pressure infiltration method, and then were extruded. The microstructure and properties of TiB2p/Al composites before and after extrusion were studied by TEM, SEM and tensile method. The results show that TiB2 particles employed are equiaxed polyhedrals and are well wetted with the aluminum alloy. Hot extruding is effective in eliminating defects such as pores, which are induced in the fabrication process. After T6 treatment and extrusion treatment, elastic modulus, tensile strength and elongation of 14%TiB2p/6061Al composites are 107 GPa, 364.1 MPa and 9.25%, respectively. While those of 20%TiB2p/6061Al composites are 120 GPa, 472.6 MPa and 9.79%, respectively, which show high strength and plasticity. A lot of dimples and a few cracked particles are observed on the fracture surfaces of the composites, which indicates good plasticity of the composites. The high strength and plasticity of TiB2p/6061Al composites are attributed to good bonding between TiB2 particles and aluminum alloy.展开更多
文摘The partially stabilized ZrO2 (PSZ) particles were introduced into TiB2 ceramics to improve its density and mechanical properties. The results show that the addition of PSZ is very effective not only in bettering the sinterability but also in enhancing the flexural strength and fracture toughness of TiB2.
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.
文摘Ni-50at.%A1 matrix composites containing 0 to 20v.% TiB_(2) particles have been successfully fabricated by HPES technique. The results show that the Vickers hardness at room temperature and the compressive yield strength from room temperature to 1000℃ of the composites increase with increasing volume fraction of the strengthening phase. Especially, the yield strength of NiAl-20TiB_(2) was approximately twice as high as that of unreinforced NiAl. The ductility of the composites at room temperature is also superior to the monolithic NiAl.
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℃
基金Project(20080430895)supported by China Postdoctoral Science FoundationProject(2008RFQXG045)supported by the Special Fund of Technological Innovation of Harbin,China。
文摘TiB_(2p)/Cu composites with high reinforcement content(φ_(p)=50%,58%and 65%)for electronic packaging applications were fabricated by squeeze casting technology.The microstructures and thermo-physical properties of the TiB_(2p)/Cu composites were investigated.The results show that TiB2 particles are homogeneous and distribute uniformly,and the TiB2-Cu interfaces are clean and free-from interfacial reaction products and amorphous layers,the densifications of the TiB_(2p)/Cu composites are higher than 98.2%. The mean linear coefficients of thermal expansion at 20-100℃for TiB_(2p)/Cu composites range from 8.3×10^(-6)to 10.8×10^(-6)/K and decrease with increasing volume fraction of TiB2.The experimental coefficients of thermal expansion agree well with the predicted values based on Turner’s model.The thermal conductivities of TiB_(2p)/Cu composites range from 167.3 to 215.4 W/(m·K),decreasing with increasing volume fraction TiB2.
文摘The microstructure and mechanical properties of TiB_2 /B_4C composites have been investi- gated.It was found that both the strength and hardness for TiB_2 greatly increase with the ad- dition of 20 to 30 wt-% B_4C,and the fracture toughness K_(IC) value remaines on the original high level.The flexure strength,Vicker's hardness and fracture toughness are 782 MPa,26.2 GPa and 7.2 MPam^(1/2),respectively,for the TiB_2-30 wt-% B_4C composite,compared to 450 MPa,21 GPa and 7.0 MPam^(1/2) for monolithic TiB_2.The toughening and strengthening mechanisms,have also been discussed.
基金Project(NCET-07-0234) supported by Program for New Century Excellent Talents in UniversityProject(20060400813) supported by China Postdoctoral Science Foundation
文摘14% and 20% (volume fraction) TiB2p/6061Al composites were fabricated by pressure infiltration method, and then were extruded. The microstructure and properties of TiB2p/Al composites before and after extrusion were studied by TEM, SEM and tensile method. The results show that TiB2 particles employed are equiaxed polyhedrals and are well wetted with the aluminum alloy. Hot extruding is effective in eliminating defects such as pores, which are induced in the fabrication process. After T6 treatment and extrusion treatment, elastic modulus, tensile strength and elongation of 14%TiB2p/6061Al composites are 107 GPa, 364.1 MPa and 9.25%, respectively. While those of 20%TiB2p/6061Al composites are 120 GPa, 472.6 MPa and 9.79%, respectively, which show high strength and plasticity. A lot of dimples and a few cracked particles are observed on the fracture surfaces of the composites, which indicates good plasticity of the composites. The high strength and plasticity of TiB2p/6061Al composites are attributed to good bonding between TiB2 particles and aluminum alloy.
