Densification Mechanism and Microstructure Evolution of Ti‐48Al‐2Cr‐8Nb Alloy by Spark Plasma Sintering

Abstract

In this work, Ti-48Al-2Cr-8Nb alloy is sintered via spark plasma sintering with pre-alloyed powders prepared by the atomized method. The densification mechanism and microstructure evolution of the spark plasma sintered Ti-48Al-2Cr-8Nb alloy are analyzed. The sintering process is divided into two stages of densification and microstructure transformation. First, the densification mechanism of the powder materials at different sintering temperatures is investigated. At the beginning of the sintering process, the powder particles are closely rearranged under pressure. In the middle of the sintering process, the plastic deformation of the powder particles and the material migration between the adjacent particles promote the densification into the high-speed stage. In the late stages of sintering, the unique equilibrium phase transition of the TiAl alloy allows the densification to be completed quickly. Additionally, the formation process and phase transition mechanism of the near gamma structure, the duplex structure, the full-lamellar structure, and spherical structure in Ti-48Al-2Cr-8Nb alloy are systematically studied.