Phase constituents and thermal expansion behavior of a NiCrAlYRe coating alloy

Phase constituents and properties of MCrAlY coating alloys play a crucial role in determining the performance of MCrAlY stand-alone overlay coatings and thermal barrier coating systems. Recent advances in computer modeling including access to involved thermodynamic databases make it possible to predict phase stabilities in these alloy systems. This article investigates the phase stabilities of a NiCrAlY coating alloy containing Re both experimentally and thermodynamically. The addition of Re promotes the formation of the Cr-rich a-phase that owns low coefficient of thermal expansion (CTE), and thereby decreases the CTE of the NiCrAlYRe coating alloy. In addition, the martensitic transformation of the B2 beta-NiAl phase is investigated. This transformation has an important influence on the microhardness of the beta-NiAl phase.