High-Energy Ball Milling and Subsequent Heat Treatment of Ti-Cu-Si-B Powders

Abstract

Metal matrix multicomponent alloys and others based on the Ti+Ti6Si2B phases are potentially attractive for structural applications. However, there is limited information in literature on the effect of alloying in stability of the Ti6Si2B compound, which presents its single-phase region close to Ti-22Si-11B alloy composition (at.-%). In this sense, this work discusses on the effect of copper addition on the stability of the Ti6Si2B compound. Elemental powder mixtures were used to prepare the Ti-xCu-22Si-11B (x=2 and 6 at.-%) alloys by high-energy ball milling and subsequent heat treatment (1100oC for 240 minutes). The as-milled Ti-Cu-Si-B powders and heat-treated samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS). Similar behavior was noted during ball milling of Ti-Cu-Si-B powders, i.e., the Ti5Si3 phase was formed after milling for 180 minutes. The mechanically alloyed and heat treated Ti-2Cu-22Si-11B alloy presented a matrix of Ti6Si2B dissolving close to 2 at.-% Cu. Precipitates of Ti5Si3 and other unknown Cu-and Fe-rich phase were also identified in microstructures of these quaternary alloys, whose amounts were increased in the mechanical alloyed and heat treated Ti-6Cu-22Si-11B alloy.