Formation of ductile α/β-Ti phases in Ti5Si3 intermetallic compound and their effects on the microstructure and mechanical properties

The effect of ductile phase on structural and mechanical properties of the refractory Ti5Si3 intermetallic compound was studied. There are two types of Ti solid solution, alpha-Ti (bcc) and beta-Ti (hcp), The later phase is unstable under the temperature of beta transus about 1138K in TiSi system. Therefore, it is necessary to add ternary element to make the beta phase stable at room temperature. It was determined that the optimum compositions of (Ti5Si3+beta-Ti) two phase alloys were Ti-32mol%Si-10mol%V and Ti-32mol%Si-5mol%Mo by using are-melted samples. Ti5Si3 monolithic, (Ti5Si3+alpha-Ti) and two types of (Ti5Si3+beta-Ti) alloys were fabricated by mechanical alloying and vacuum hot pressing method. Mechanical properties including fracture toughness and high temperature strength were investigated by micro-Vickers hardness test from room temperature to 1373K.