Abstract:

The void nucleation and growth around an inclusion in nickel-based single crystal superalloys are analyzed by using the cohesive zone model to simulate the interface between the matrix and the inclusion. The strength of the interface includes its normal and shear strengths. The relative void volume fraction is noticeably different for different cohesive strengths. The smaller the cohesive strength is, the easier the void nucleation and the higher the void growth rate are. The stress triaxility is the main driving force of void nucleation and growth. The initial location of the interfacial debonding and subsequent crack propagation are different when the stress triaxility changes. At low stress triaxility, void deformation mainly exhibits itself as shape change; at higher stress triaxility, it mainly exhibits itself as bulk expansion. Lode parameter has great effect on void growth and its shape change. The crystallographic orientation has considerable influence on void growth from initial debonding through complete separation to subsequent growth.

Key words: single crystal superalloy, inclusions, void, interface debonding, stress triaxility, cohesive element