SPS制备TiAl基合金微观组织演变研究

Microstructural Evolution Mechanisms of TiAl Based Alloy Prepared by Spark Plasma Sintering

以等离子旋转电极雾化球形Ti47Al2Cr2Nb0.2W预合金粉末为原料,采用SPS技术在不同烧结温度下(1100,1200,1250,1300℃)制备Ti Al基合金。结合XRD、SEM及TEM等检测手段,对预合金粉末致密化过程中显微组织演变以及不同烧结温度对力学性能的影响进行了系统研究。结果表明:当烧结温度超过1200℃时,组织内存在少量高温残留B2相,且随着烧结温度的升高,β相(B2相)含量有所增加;烧结温度在1100℃时合金具有最高的抗压缩断裂强度、抗拉伸断裂强度和断裂应变,分别为2367 MPa、600 MPa和2.25%;α2相、β相和γ相存在如下晶体学关系:(0001)α2∥{111}γ∥{110}β,■;1300℃烧结样品中有形变诱导α2→γ相变以及形变孪晶产生。

Using atomizing spherical Ti47Al2Cr2Nb0.2W prealloyed powder with plasma rotating electrode as starting material,Ti Al-based alloy was prepared by SPS technology at different sintering temperatures(1100°C,1200°C,1250°C,1300°C).The microstructure evolution of the pre-alloyed powder during densification was systematically studied by XRD,SEM and TEM and the effects of different sintering temperatures on mechanical properties were also investigated.The results show that when the sintering temperature exceeds 1200°C,there is a small amount of high temperature residual B2 phase in the microstructure,and theβphase(B2 phase)content increases with the increase of sintering temperature.The alloy has the highest compressive fracture strength,tensile fracture strength and fracture strain at 1100°C,which are 2367 MPa,600 MPa and 2.25%,respectively.Theα2 phase,βphase andγphase have the following crystallographic relationship:(0001)α2∥{111}γ∥{110}β,■.Deformation inducedα2→γphase transformation and deformation twin formation occur in the sample sintered at 1300°C.