Suppression of Grain Boundary α Formation by Addition of Silicon in a Near-β Titanium Alloy

Abstract

The effect of Si addition on the microstructure and mechanical properties of a near-¢ titanium alloy Ti-17 with fully lamella microstructure was investigated. It was found that the microstructure of Ti-17 with silicon exhibited the absence of a continuously thick ¡ layer along prior-¢ grain boundaries (grain boundary ¡), while the grain boundary ¡ was distinctively formed in Ti-17 without Si. The formation of (Ti, Zr) silicide particles at the prior-¢ grain interior and its grain boundaries were observed, and the presence of these particles were related to the disappearance of grain boundary ¡ similar to the oxygen scavenging effect of boride particles reported previously. With regard to mechanical properties, Ti-17 with silicon exhibits higher strength and lower ductility compared with Ti-17 without Si. Ductile transgranular fracture morphology was observed even on the fracture surface of Ti-17 with Si after tensile test. [