Evolution of intermetallic compounds in Ti-Al-Nb system by the action of mechanoactivation and spark plasma sintering

Abstract

The present study shows promising approach to produce hydrogen-accumulated rechargeable intermetallic compounds (IMC) from three-component powder composition Ti-25Al- 25Nb (at%), through experimentally chosen best modes and combined technological processes. The study includes research results on the effect of mechanoactivation (MA) process and following spark plasma sintering (SPS) technique on structural phase state of intermetallic Ti-Al-Nb composites. It was revealed that upon activation of the initial powder mixtures during their machining, intermetallic phases are formed by the interpenetration of aluminum into titanium and niobium lattices with the formation of solid solutions (Ti, Al) and (Nb, Al). It is found out, that the combination of MA and SPS is good for producing fine-graded predicted micro-structures in Ti-Al-Nb system owing to the activation of particle surface and formation of intermetallic phases at the preparation stage of powder mixture using MA technique as well as due to the effect of fast consolidation using SPS. This points to the fact of prospect for creating metal hydrides by combining MA and SPS techniques that makes it possible to obtain fine-grained IMC containing fair amount of O-phase.

Keywords

• intermetallic compounds
• ti-25al-25nb alloy
• spark plasma sintering
• mechanoactivation
• o-phase