Titanium-Tantalum Alloy Powder Produced by the Plasma Rotating Electrode Process (PREP)

Abstract

Microstructure of Ti-28Ta powders produced by plasma rotating electrode process (PREP) was investigated by using scanning electron microscopy (SEM), optical microscopy (OM), and transmission electronic microscopy (TEM). Phase constituent of the PREP Ti-28Ta powders was analyzed by X-ray diffraction (XRD). It was found that microstructure of the PREP Ti-28Ta powders was dependent on the powder particle sizes. Predominant martensitic α”, some metastable β and trace athermal ω phases were observed in the powders with the small diameter. While, phase constituent of the PREP Ti-28Ta powders with the large particle size was predominant metastable β, some martensitic α” and trace athermal ω. With the reduction of the powder particle size, the amount of martensitic α” increased and the metastable β decreased. The martensitic α” was formed preferentially on the metastable β grain boundaries of the PREP Ti-28Ta powders. The increase of α” phase and decrease of β with reduction of the powder particle size is attributed to the increase of the volume of the grain boundaries due to the grain refinement.