すべり摩擦を受けた(001)銅単結晶における結晶の回転と小角粒界の形成

Abstract

A sliding wear test was conducted on a copper single crystal having (001) surface. Formation of fine grains was recognized locally near the worn surface. To find a criterion for generation of low-angle boundaries during the sliding wear, lattice rotation of the matrix and misorientation between adjoining points were measured using electron backscatter diffraction (EBSD) analysis. Particularly, we paid attention to the low-angle boundaries that were distant from the worn surface. Beneath the fine-grained area, orientation of the matrix continuously changed along the direction of depth. The continuous lattice rotation was understood from a concept of geometrically necessary (GN) dislocations whose density is proportional to a lattice rotation gradient ∂φ/∂x. Increase in the lattice rotation gradient that was measured from the EBSD analysis was recognized near the worn surface. However, at the subsurface layer where low-angle boundaries were generated, the lattice rotation gradient was no longer a function of depth, and was smaller than that of the region where the continuous lattice rotation occurred. Accordingly, the generation of the low-angle boundary could be caused by rearrangement of the dislocations that was induced by the sliding wear.