Effect of Cr Content on Isothermal Transformation Kinetics and TTT Diagram of Ti5Mo5V3Al-Cr Alloys

Abstract

The relationship between phase transformation and time of Ti5Mo5V3Al-Cr (Cr content is 1.0%,3.0%,5.0%,7.0% and 9.0%,mass fraction) alloys at 420,520,620℃was studied by in-situ thermal expansion and XRD method. According to the Johnson-Mehl-Avrami equation and experimental results,the kinetic parameters of Ti5Mo5V3Al-Cr alloys were obtained by fitting, and the dynamic equation of the system was established. Furthermore,based on the experimental results and theoretical calculation results, the time temperature transformation (TTT) contrast curve of Ti5Mo5V3Al-Cr alloys was plotted. The results show that the calculated results are in good agreement with the experimental results. Besides, 1Cr and 3Cr alloys have a fast phase change speed in the test temperature range of 420,520,620℃; 5Cr and 7Cr alloys have the fastest alpha phase transition velocity at the "nose temperature zone" of 550℃. The "nose temperature zone" of 9Cr alloy is not obvious, which means that the phase transition rate is slow.

Keywords

• Cr content
• Ti5Mo5V3Al-Cr alloy
• phase transformation
• dynamic equation
• TTT diagram