Effect of Solution Temperature on Microstructure and Mechanical Properties of Ti-5Al5Mo5V3Cr1Zr Alloy

The work aims to reveal relationship between solution temperature, microstructure, and mechanical properties of Ti-5Al5Mo5V3Cr1Zr (Ti-55 531) alloy. The alloys are prepared via solution processing in a temperature ranging from T (beta) - 100 degrees C (where T (beta) is beta-transus temperature) to T (beta) + 100 degrees C for 2 h; and then air cooled, aged at 600 degrees C for 6 h, and air cooled again. Results indicate that solution temperature range (from T (beta) - 100 degrees C to T (beta) + 100 degrees C) can be divided into following five ranges according to performance of Ti-55 531 alloy. The alloy presents excellent mechanical performance combining high strength and good ductility for solution temperatures ranging from T (beta) - 50 degrees C to T (beta) - 30 degrees C and from T (beta) + 10 degrees C to T (beta) + 30 degrees C. Interestingly, the Ti-55 531 alloy exhibits a dramatically enhanced strength, while ductility drops rapidly as solution temperature exceeds T (beta) + 70 degrees C. The enhanced strength's main reason is that grain boundary alpha phase changes from continuous to discontinuous with increasing solution temperature; nevertheless, the increased size of beta grains results in a reduction in ductility. Thus, continuity of grain boundary alpha phase has a dramatical influence on performance of Ti-55 531 alloy.