Etat des recherches sur les aluminiures de titane monolithiques à base de Ti₃AI et de TiAl

Monolithic titanium aluminides based on Ti₃Al and TiAl - A review

¹ IFI, Université de Marne-la-Vallée, Champs-sur-Marne, France
² Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615, Université Claude Bernard Lyon I, Villeurbanne, France

Abstract

Titanium aluminides based on TiAl and Ti₃Al are emerging as revolutionary high temperature materials. In order to confer these materials the thermomechanical properties required for industrial applications, two phase alloys are developed by microalloying. That leads to formulate different alloy compositions adapted to the fabrication process and to the specific properties required for engineering applications. Knowledge of the fundamental understanding such as composition-structure-mechanical property relationships, microalloying effects and temperature dependence of plasticity micromechanisms are in progress and are used to optimize mechanical properties such as yield and creep strengths, tensile ductility and fracture resistance. Cast processing of XD™ near-y titanium aluminides has been successfully develo¬ped to manufacture near-net shaped components. For wrought alloys, investigation is aimed at producing large homogenized ingots and at improving the balance of properties by thermome-chanical processing and heat treatments. Microstructure control is attempted by examining the role of solidification paths, phase relations and transformations and microalloying effects. The research efforts directed towards achieving balanced engineering properties are reviewed.