Effect of solution heat treatment on creep properties of a nickel-based single crystal superalloy

Abstract

A novel low-density nickel-based single-crystal superalloy was prepared and the effect of solution treatment on the creep deformation mechanism was systematically investigated. The results reveal that the creep life increases with the increase of solution treatment time, which can be ascribed to microstructural homogenization. However, when the solution treatment time exceeds a threshold limit, the relative proportion of undesirable defects significantly increases, which accelerates the failure and compromises the creep life. The homogenization of the composition leads to the precipitation of a more homogenized γ′ phase and, in turn, results in a more uniform and dense dislocation network, thus hindering the dislocation movement and improving the creep life. The undesirable defects may lead to the stress concentration and weaken the effect of the dislocation network, thus accelerating the creep process and the dislocation are more likely to shear into the γ′ phase. In general, the current study provides guidance for selecting a more reasonable solution treatment time to improve the creep strength.

Keywords

• Nickel-based single crystal superalloys
• Microstructural evolution
• Creep behavior
• Solution heat-treatment