Thèse . H/F - Doctorat.Gouv.Fr

Établissement : Mines Paris-PSL
École doctorale : SFA - Sciences Fondamentales et Appliquées
Laboratoire de recherche : Centre de Mise en Forme des Matériaux
Direction de la thèse : Daniel PINO MUÑOZ
Début de la thèse : 2026-10-01
Date limite de candidature : 2026-08-31T23:59:59

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Titanium alloys are widely used in demanding applications such as aerospace, biomedical implants, and energy systems due to their high strength-to-weight ratio and excellent corrosion resistance. In these applications, controlling the microstructure-and in particular the phase distribution -is essential, as it directly governs mechanical properties such as strength, ductility, and fatigue resistance. Titanium alloys can exist in two different crystal structures: the low temperature phase (hexagonal) and the high temperature phase (cubic). The transition between these two phases is usually described by the transus temperature, above which the phase becomes stable. However, experiments over the past 40 years have shown that this diffusive transformation can also be strongly influenced by mechanical deformation. In particular, applying stress can shift the transus temperature by as much as 50 °C, meaning that phase transformations can occur at temperatures where they would not normally be expected based on standard phase diagrams. This reveals that deformation does not only affect the transformation kinetics but also modifies phase equilibrium. Despite many experimental observations, there is currently no model capable of reliably predicting how the phase forms during deformation (-> ), nor the reverse transformation (-> ) that takes place after the load is removed. This lack of understanding limits our ability to control microstructures in industrial processes. The goal of this PhD project is therefore, through coupled experimental and modelling work, to better understand the physical mechanisms behind the deformation-induced phase transformations in titanium and its alloys, and to develop a model that can describe both the transformation under stress and the subsequent reverse transformation. Such a model would provide new insights into how mechanical loading can fundamentally alter phase stability in titanium alloys.

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