等离子电火花烧结温度对TiAl合金微观组织和力学性能的影响

以等离子旋转电极球形Ti-45Al-2Cr-2Nb-0.2W预合金粉末为原料,采用等离子电火花烧结工艺在1150到1250℃范围内制备了高致密度和显微组织均匀一致的细晶钛铝基合金。烧结温度为1150℃时可获得均匀组织的α2+γ双态组织,并呈现出烧结温度范围内最高的断裂强度(1026MPa)和室温延伸率(1.12%);烧结温度为1250℃时可获得全片层α2/γ组织,烧结体的断裂强度和室温延伸率分别为953MPa和0.92%。双态组织(DP)的断裂模式是等轴γ晶内的穿晶断裂和片层晶团内的晶间断裂;而DP组织则为穿片层断裂、片层间断裂和台阶撕裂3种模式的复合模式。

Effect of SPS Temperature on Microstructure and Mechanical Properties of TiAl Alloys

The spark plasma sintering(SPS) technique was used to consolidate pre-alloyed powder of Ti-45Al-2Cr-2Nb-0.2W produced by plasma rotating electrode processing(PREP).The powder was sintered at temperatures between 1150 and 1250 ℃,and the effects of sintering temperature on the microstructure and the mechanical properties were studied.The optimized conditions yield high densities and uniform microstructure.Specimens sintered at 1150 ?C are characterized by fine duplex microstructure,leading to superior room temperature mechanical properties with a tensile strength of 1026 MPa and an elongation of 1.12%,while the specimen sintered at 1250℃ are of fully lamellar microstructure with a tensile strength of 953 MPa and an elongation of 0.92%.The main fracture mode in the duplex microstructure is transgranular in the equiaxed γ grains and interlamellar in the lamellar colonies,and for the fully lamellar microstructure the dominant fracture mode is interlamellar,translamellar and stepwise failure.