Effect of long-term thermal exposure on microstructure and creep properties of DD5 single crystal superalloy

Abstract

Nickel-based single crystal superalloys are widely employed for hot sections of aircraft engines and gas turbines because of their excellent high temperature creep and fatigue strengths [1][2][3] . Single crystal superalloys are strengthened by high volume fractions of cubical γ' phase embedded coherently in γ matrix phase, and by the addition of a variety of refractory elements [4,5] , such as Re, W and Mo. The addition of refractory elements with higher melting points can enhance the solid solution strengthening and creep properties, but meanwhile, the freckles and precipitation of harmful phases may occur [6] . Adding a small amount of C element may form carbides, which can consume heavy refractory elements to reduce the probability of freckles and harmful phases formation [7,8] .