Phase transformation kinetics of Ti-1300 alloy during continuous heating

摘要

The a + b → b phase transformation kinetics of Ti-1300 alloy during continuous heating at different heating rates were investigated using dilatometric method.Results show that the curves of the a + b → b phase transformation exhibit a typical S-shaped pattern, which indicates that the a + b → b phase transformation is a nucleation-growth-controlled process. The overall activation energy of the a + b → b transformation of the alloy is797 k J mol-1. The nucleation and growth mechanism of the a + b → b transformation was also investigated using the non-isothermal Avrami exponent. The Avrami exponent during a + b → b transformation process significantly changes with transformed volume fraction increasing, which indicates that the a + b → b transformation mechanism in the Ti-1300 alloy varies at different sections.