The tension/compression asymmetry of a high γ' volume fraction nickel-based single-crystal superalloy

A high γ' volume fraction single-crystal superalloy specimens with various crystallographic orientations were tested under uniaxial tension/compression. The results show that there is apparent tension/compression asymmetry at the initial yielding (plastic strain < 0.2%, where no Kear-Wilsdorf lock and superlattice stacking fault generates during the deformation, so the existing models such as LCP and PPV cannot apply to two-phase nickel-based single-crystal superalloys). In this paper, the effect of elastic deformation on tension/compression asymmetry is discussed. A new constitutive model of two-phase nickel-based single-crystal superalloys is proposed to simulate the tension/compression asymmetry of yield strength. The model could well explain tension/compression asymmetry of twophase alloy in [0 0 1] and [0 1 1] orientations, however it is not suitable for [1 1 1] orientation mainly due to the different slip mode.