Preparation of High-Temperature TiAl Pre-alloyed Powder by PREP and Its Densification Microstructure Research

Abstract:

High-temperature TiAl pre-alloyed powder was produced by Plasma Rotating Electrode Process (PREP), and its characteristics were investigated. The results show that the as-prepared particle size mostly ranges from 46 μm to 150 μm, and its distribution is bimodal distribution. The freezing microstructure and phase of pre-alloyed powder are related to its granularity. The microstructure of powder with large particle size is usually dendritic structure, while that with small particle size shows smooth surface. The phase of as-prepared powder is mainly hexagonal α2 phase, but powder with particle size less than 46 μm contains some β phase, and powder with particle size larger than 200 μm has a small amount of γm phase. It is obvious that the powder with different phase and microstructure has an inherited effect on the densification microstructure formed by hot isostatic pressing. Powder with large particle size is prone to forming the coarsening lamellae structure and residual powder boundary in the densification microstructure.