Microstructural characterization and properties of Ti-28Ta at.% powders produced by plasma rotating electrode process

摘要

Ti-28 at.% Ta powders were produced by rapid solidification via plasma rotating electrode process (PREP). It is found that microstructure, morphology and phase constituents of Ti-28Ta powders are particle size dependent. Small powder particle exhibit the formation of predominant martensitic alpha '' and minor metastable beta, whilst large particles consist of primary metastable beta with minor martensitic alpha '' phase. The amount of martensitic alpha '' increases while the amount of metastable beta phase decreases with decreasing the particle size. The martensitic alpha '' lath with the size of about 50 nm wide and 1 mu m long are formed preferentially at the beta grain boundaries. The martensitic transformation start temperature (M-s) and peak temperature (M-p) are similar to 390 degrees C and similar to 340 degrees C respectively for the Ti-28Ta powders with the particle size between 40 and 65 mu m. An increased Vickers micro-hardness is obtained and is associated with decreasing particle size. (C) 2017 Elsevier B.V. All rights reserved.