In order to improve the mechanical properties of Ti Al alloys, especially the ductility at room temperature, and to study the effect of boron(B) on Ti Al alloys, different contents(0, 0.1, 0.3, 0.6, 0.9, 1.2, at.%) of...In order to improve the mechanical properties of Ti Al alloys, especially the ductility at room temperature, and to study the effect of boron(B) on Ti Al alloys, different contents(0, 0.1, 0.3, 0.6, 0.9, 1.2, at.%) of B were added into Ti-44Al-6Nb alloys to prepare ingots. The surface quality, macrostructure, microstructure, compressive properties and fracture surface of the ingots were studied. The results show that B has little influence on the surface quality except that there are some dark spots on the surface when the content of B is 0.9%. B can refine the grains. The average grain size decrease from about 0.8 mm to 0.088 mm with increasing B content. Meanwhile, the grain morphology of these ingots changes from big equiaxed grains with lamellars to fine equiaxed grains. When the content of B is 1.2%, the primary Ti B2 phase forms in the liquid phase and increases the nucleation rate, leading to further refinement of the grains. The compressive testing results show that B can increase the strength and the ductility, the compressive strength and compressibility can reach 2,037.8 MPa and 26.7% from 1,156.2 MPa and 10.2% when the boron content is 0.6%, which is resulted from grain refining and grain boundary strengthening. It is found that the compressive strength and the compressibility are relatively stable when the B content is more than 0.3%.展开更多
Ti44A16 Nb-based alloy ingots with different cerium(Ce)contents(0,0.05,0.10,0.15,0.20;at%)were prepared by non-consumable vacuum arc smelting furnace(WK-Ⅱ).The surface quality,macrostructure,microstructure,compressiv...Ti44A16 Nb-based alloy ingots with different cerium(Ce)contents(0,0.05,0.10,0.15,0.20;at%)were prepared by non-consumable vacuum arc smelting furnace(WK-Ⅱ).The surface quality,macrostructure,microstructure,compressive properties and fracture morphology of these ingots were studied.The results show that Ce has few influences on the surface quality.Ce can refine grain size and the average grain size decreases from 0.50 to 0.19 mm with the increase of Ce content.Meanwhile,the microstructure morphology of these ingots changes from large lamellar microstructure to dual-phase microstructure.With addition of Ce,CeO and AlCe3 are formed during melting and solidifying,which act as the core of heterogeneous nucleation and refine the grain.The compressive testing results show that Ce can improve strength and ductility.The ultimate compressive strength increases from 1156.2 to 1472.2 MPa with Ce content increasing from 0 at%to 0.20 at%.The compression ratio is improved from 10.2%to 15.3%with Ce content increasing from 0 at%to 0.10 at%.The refined crystalline strengthening and grain boundary strengthening are the main reasons for the improvement of compressive property.展开更多
基金Project (2011CB605505) supported by the National Basic Research Program of ChinaProject (2008AA03A233) supported by the National High-Tech Research and Development Program of China
基金supported by the Program of New Century Excellent Talents in University(NCET-12-0153)National Natural Science of Foundation of China(51274076)National Basic Research Program of China(2011CB605504)
文摘In order to improve the mechanical properties of Ti Al alloys, especially the ductility at room temperature, and to study the effect of boron(B) on Ti Al alloys, different contents(0, 0.1, 0.3, 0.6, 0.9, 1.2, at.%) of B were added into Ti-44Al-6Nb alloys to prepare ingots. The surface quality, macrostructure, microstructure, compressive properties and fracture surface of the ingots were studied. The results show that B has little influence on the surface quality except that there are some dark spots on the surface when the content of B is 0.9%. B can refine the grains. The average grain size decrease from about 0.8 mm to 0.088 mm with increasing B content. Meanwhile, the grain morphology of these ingots changes from big equiaxed grains with lamellars to fine equiaxed grains. When the content of B is 1.2%, the primary Ti B2 phase forms in the liquid phase and increases the nucleation rate, leading to further refinement of the grains. The compressive testing results show that B can increase the strength and the ductility, the compressive strength and compressibility can reach 2,037.8 MPa and 26.7% from 1,156.2 MPa and 10.2% when the boron content is 0.6%, which is resulted from grain refining and grain boundary strengthening. It is found that the compressive strength and the compressibility are relatively stable when the B content is more than 0.3%.
基金financially supported by the National Natural Science of Foundation of China(No.51274076)the Program of New Century Excellent Talents in University(No.NCET12-0153)the National Basic Research Program of China(No.2011CB605504)
文摘Ti44A16 Nb-based alloy ingots with different cerium(Ce)contents(0,0.05,0.10,0.15,0.20;at%)were prepared by non-consumable vacuum arc smelting furnace(WK-Ⅱ).The surface quality,macrostructure,microstructure,compressive properties and fracture morphology of these ingots were studied.The results show that Ce has few influences on the surface quality.Ce can refine grain size and the average grain size decreases from 0.50 to 0.19 mm with the increase of Ce content.Meanwhile,the microstructure morphology of these ingots changes from large lamellar microstructure to dual-phase microstructure.With addition of Ce,CeO and AlCe3 are formed during melting and solidifying,which act as the core of heterogeneous nucleation and refine the grain.The compressive testing results show that Ce can improve strength and ductility.The ultimate compressive strength increases from 1156.2 to 1472.2 MPa with Ce content increasing from 0 at%to 0.20 at%.The compression ratio is improved from 10.2%to 15.3%with Ce content increasing from 0 at%to 0.10 at%.The refined crystalline strengthening and grain boundary strengthening are the main reasons for the improvement of compressive property.
