Effects of solution heat treatment on the microstructure, oxidation, and mechanical properties of a cast Ni3Al-based intermetallic alloy

Solution heat treatment is employed in an attempt to improve oxidation and mechanical properties of an as-cast Ni₃Al alloy (IC221M) at operation temperature, 900 °C. Solution heat treatment was hypothesized to have beneficial effects through dissolving γ Ni₅Zr eutectic into the matrix. The microstructures, oxidation behavior in air at 900 °C, and mechanical properties with aging times at 900 °C were examined after solution heat treatment of as-cast Ni₃Al alloy in Ar for up to 100 h at 1100 °C. The oxide penetration depth into the matrix was dramatically decreased and more homogeneous surface oxides were obtained relative to the no solution, treatment case. Hardness was improved by solution heat treatment due to a solid solution strengthening effect by Zr, but the tensile properties after solution heat treatment were not significantly different from those prior to treatment.