Influence of Heat Treatment on Microstructure and Mechanical Characteristics of the Titanium Alloy Ti-5Al-5 V-2Mo-Cr with Metastable β-Phase

In this study, mechanical characteristics and microstructural evolution of Ti-5Al-5 V-2Mo-Cr titanium alloy after quenching from different temperatures and tensile deformation were investigated. It was established that the destabilization of the b-phase in relation to the development of b -> a" stress-induced martensitic transformation (SIMT) with an increase in quenching temperature from 800 to 860 celcius contributes to the appearance of "double yield mechanical behavior" and superelasticity effect during tensile tests causes an increase in strength properties and impact toughness characteristics of the alloy. SIMT quenched from 860 celcius alloy also leads to the change in fracture surface micromechanism at impact tests from intergranular cracking along the boundaries of a/b-phases to destruction along the boundaries of a"-martensite packets. X-ray phase analysis and TEM methods have been used to detect the formation of needle-like a"-martensite, which is formed in the neck zone of tensile specimen quenched from the temperature of 860 celcius.