Modeling of Ni–Cr–Mo based alloys: Part I—phase stability

The CALPHAD approach is applied to the study of the stability of several candidate Ni–Cr–Mo based alloys for use in waste disposal canisters for the Yucca Mountain Project (YMP). The stability of occurring phases in the as-fabricated materials is investigated since temporal evolution of precipitates at service temperatures can significantly alter their corrosion resistance and mechanical properties. To account for the stability of the Ni₂Cr phase and the hypothetical Ni₂Mo and Ni₂W phases, available thermodynamic data and ab initio electronic structure-based results were employed. A comparative study of property diagrams for the nominal composition of several YMP candidate alloys is presented. These results form the basis for experimental and theoretical studies of kinetics of phase transformation and aging to be presented in Part II.