Liquid metal penetration in metallic polycrystals: New tools for a challenging unsolved problem of materials science

The set of works performed in the framework of the GEDEON program on liquid metal embrittlement is presented. We focus on the role of wetting of grain boundaries (CBs) in the rapid penetration of a liquid metal along GB, and we point out the thermodynamic and kinetic parameters involved in this phenomenon. Since the paper of Mullins (1957) and the experimental studies performed in the 60's, new tools are available for the observation of grain boundary grooving (and wetting) at a scale below one micron. They are scanning electron microscopy (SEM) and atomic force microscopy (AFM). It will be shown on copper-, iron- and nickel-based alloys that accurate observations with these facilities allow to reveal the role of interface faceting in grain boundary penetration and to propose a new model which takes into account this new feature

Etude du comportement à hautes températures d’un alliage TiAl densifié par frittage flash

International audienceLes travaux effectués portent sur la caractérisation microstructurale et le comportement mécanique d’un alliage TiAl en cours de développement, pour la fabrication d’aubes de turbine des étages à basse pression. Nous présenterons ainsi les caractéristiques d’un alliage TiAl élaboré au CEMES par frittage flash ainsi que son comportement à haute température