Spherical TiAl Alloy Powders by PREP: Preparation, Microstructure and Properties

Abstract

TiAl alloy powders were prepared by plasma rotate electrode pulverization (PREP) with high speed. The effect of preparation process on the microstructure and properties of powders was studied. The results showed that the titanium aluminum powder prepared by PREP method was solid and spherical without satellite powder. The powders had two morphologies: cracked surface and smooth surface. The relationship between particle size and surface morphology was as follows: the smaller the particle size, the smoother the surface. Ti, Nb and Gr elements were uniformly distributed, while Al elements were segregated, but no alloy element loss occurred. The powderswere mainly composed of γ-TiAl and α2-Ti3Al phase and contained a small amount of NbCr2 phase. The average thickness of laminates of α 2+γ was about 0.2μm. Thelamellar thickness of γ phase was about 20nm. The long axis of NbCr2 phase was 200nm, and the short axis was 50 ~ 100nm. The higher the rotating speed of the electrode, the smaller the particle size and the higher the sphericity of the powders. With the increase of plasma generator current, the particle size decreased and the sphericity increased. The yield of - 100 mesh ~ + 325 mesh powders for EBSM molding could reach more than 80.68 %, when42000r / min and 670A process parameters were adopted.