Evolution of microstructure during high temperature low cycle fatigue of high purity aluminiumo ligocrystals

Abstract

For a variety of metallic materials, conspicuous microstructural changes were observed during elevated temperature cyclic deformation owing to grain growth, grain boundary motion, and reorientation of the grain boundaries under 45° with respect to the stress axis. These phenomena were investigated in high purity aluminium. The evolution of microstructure and microtexture during high temperature low cycle fatigue can be observed very well using oligocrystals (i.e. specimens consisting of less than 15 grains in the deformed area). The orientation of individual grains and the spatial arrangement of grain boundaries can be characterised completely owing to the extremely large grain size. After several deformation steps the movement of the grain boundaries was measured using optical microscopy without additional preparation, therefore, each migration step of the grain boundary and each microtextural change of grains can be analysed.