Nondestructive evaluation of dislocation structure in cyclically deformed Ni3Fe single crystals using magnetic techniques

Abstract

The deformation substructure in Ni3Fe single crystals cyclically deformed at constant plastic shear strain amplitudes (γpl) consisted of two phases: the matrix with planar dislocation arrangement and the persistent slip band (PSB) having a three dimensional cell structure. The saturation stress remained almost constant regardless of γpl by adjusting the volume fraction of PSB. Anisotropy of high-field susceptibility in cyclically deformed Ni3Fe single crystals was measured in the (111) discs. Two types of magnetic anisotropy caused by atom rearrangement near the antiphase boundary (APB) and internal stress around dislocations were observed in fatigued Ni3Fe single crystals. The anisotropy data were subjected to the Fourier-type transformation and were split into separate anisotropy functions depending on the type of lattice defects. The magnitude ratio of dislocation- to APB-dependent anisotropy increases linearly with increasing γpl. This strongly suggests that Winter’s two-phase model can be applied to both mechanical and magnetic properties. Thus, nondestructive evaluation of dislocation structure in cyclically deformed Ni3Fe single crystals could be done by analyzing the magnetic anisotropy induced by cyclic deformation.