Fatigue properties of strongly textured bulk NiW

Abstract

The cyclic plasticity of Ni–5at.%W with a strong cube texture was investigated for two different deformation directions and at two different plastic strain amplitudes of 2.5⋅10−4 and 5⋅10−4 in a symmetric push–pull-mode. To prevent bending of the thin samples during the compression half-cycles, a novel sample suspension was successfully integrated into the mechanical tests.Samples deformed parallel to a 〈001〉or a〈011〉direction of the cube texture displayed significant differences in both plastic behavior (i.e., lifetime, correlation of saturation stress amplitude and plastic strain amplitude) and microcrack characteristics. The majority of these effects can be interpreted as a consequence of the peculiar grain structure of the material, consisting of a “matrix” of cube oriented grains with small embedded grain regions of differing orientations. The hysteresis loops of all samples exhibit a short region of concave curvature shortly before the inversion points, possible reasons of which are discussed.