Microstructure and high-temperature mechanical properties of TiAl composites with Ti-rich region prepared via powder metallurgy

TiAl alloys are recognized for their substantial application potential in high-temperature aerospace contexts. However, their limited plasticity presents significant challenges in the realm of plastic processing. In this paper, TiAl composites with Ti-rich region were prepared by hot-pressing sintering using Ti powders and Ti-48Al-2Cr2Nb alloy powders as raw materials. The microstructure, high temperature tensile properties and fracture behavior of TiAl composites were studied. The findings suggest that the formation of the Ti-rich region is linked to the diffusion reaction of elements between Ti powders and the matrix during the sintering process. At high temperatures, the TiAl composite exhibits superior ductility. Specifically, at 800 degrees C, 900 degrees C, and 1000 degrees C, the tensile strengths are 358.57 MPa, 178.71 MPa, and 59.62 MPa, respectively, with corresponding elongations of 29.45 %, 39.53 %, and 97.31 %. The excellent ductility is attributed to the formation of dislocation slip, deformation twins in the TiAl matrix and the deformation coordination between the Ti-rich region and the TiAl matrix. Throughout the fracture process, the existence of Ti-rich region facilitates the deformation coordination of TiAl composite, restrains crack propagation, and delays the fracture occurrence.