Gleeble-Assisted Investigation and Thermokinetics Simulation of α Phase Isothermal Precipitation during Short-Time Duplex Heat Treatment of Ti-6Al-4V Alloy

• Published in: Journal of materials engineering and performance 2022, Vol.31 (9), p.7517-7526
• Main Authors: Kherrouba, Nabil, Carron, Denis, Kouba, Ramdhane, Bouabdallah, Mabrouk, Badji, Riad
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion and Coatings; Engineering Design; Engineering Sciences; Materials Science; Quality Control; Reliability; Safety and Risk; Technical Article; Tribology
• ISSN: 1059-9495; 1544-1024
• DOI: 10.1007/s11665-022-06775-8

The precipitation mechanism and kinetics of the secondary α phase during short-time duplex heat treatment of the Ti-6Al-4V alloy were investigated. The precipitation kinetics was determined by means of in situ isothermal electrical resistivity tests in a Gleeble thermomechanical testing machine in the temperature range of 600-700 °C. The results showed that the higher the aging temperature, the faster the secondary α phase precipitation, which obeys the Kolmogorov–Johnson–Mehl–Avrami (KJMA) equation with an Avrami parameter n = 1. The precipitation process was also investigated by simulation using the thermokinetic software MatCalc. Results of the simulation on MatCalc indicated that the secondary α phase nucleation ended at an earlier stage of the precipitation and that the latter is mainly controlled by the growth of secondary α phase precipitates. Increasing the aging temperature resulted in an increase of the precipitate’s size with an activation energy of Q = 62 kJ/mol for the process. Evolution of the simulated elements contents showed that only the vanadium concentration in the β phase changed significantly during the isothermal aging. Thus, the growth of the secondary α phase is governed by the vanadium diffusion into the β phase.