Cyclic deformation behavior of Ni3Nb single crystals deforming by slip on (010)[100]

Cyclic deformation behavior in Ni3Nb single crystals deforming by slip on (010)[100] was investigated. Fatigue tests were performed in a symmetrical push/pull mode at a fixed total strain amplitude (Δε) from ±0.06 to ±0.30% at ambient temperature. The cyclic hardening behavior varied below and above Δε=±0.15%. In the low strain amplitude group, the maximum stress amplitude reached a saturated value after initial strong hardening, while the cyclic hardening behavior in the high strain amplitude group were divided into three stages including the initial strong hardening. This initial strong hardening is related to the exhaustion hardening caused by the Kear–Wilsdorf locking. The hardening mechanism in each stage is discussed focusing on the cyclic stress-strain behavior, slip trace morphology and dislocation structure.