Study of kinetics phase transformations during continuous heating and cooling in Ti-6Al-4V

Auteurs :  Nabil KHERROUBA, Brahim MEHDI, Lyacine RABAHI, Riad BADJI
Année : 2017
Domaine : Métallurgie
Type : Communication
Conférence: 2nd International Conference on Light Materials – Science and Technology LightMAT 2017
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Mots clés : Ti-6Al-4V, additivity rule, KJMA equation, sympathetic nucleation

Résumé : 

The aim of this work is to investigate the effect of the solution treatment temperature on the β → α during continuous cooling from temperatures above the transus β in the Ti-6Al-4V titanium alloy. The microstructural analysis reveals the nucleation of two morphologies of α phase: αGB layer that nucleates along the β/β grain boundaries and αW platelets nucleating from the αGB layer or directly on the β/β grain boundaries. An increase in the solution treatment temperature causes a β grain coarsening and delays the formation of the α phase. An approach based on the additivity rule to adapt the KJMA equation to non-isothermal phase transformation has been used to determine the kinetics parameters. This approach permits also to study the α + β → β phase transformation kinetics during continuous heating. This parameters have been discussed according to the microstructure evolution.