In-situ surface characterization of a binary aluminum alloy during tensile deformation

Abstract

A metal surface that is not contacting a tool typically roughens with increasing plastic strain. This form of roughening, which is often referred to as orange peel, results from non-uniform plastic flow of surface grains that are not constrained by a tool surface and hence are free to deform out of the surface plane. Although a substantial body of literature exists on orange peel, there appears to have been little work on the characterization of individual grain surface topography at the nanometric scale resulting from tensile deformation. The information gained from tracking changes in grain topography on the sub-micron scale stands to provide insight into both surface and near-surface grain deformation which could aid in the development of finite element models of non-uniform plastic flow of metals. From a materials design standpoint, a knowledge of the topographical changes that occur on various grains could provide insight as to how metal alloys can be manufactured so that free grain roughening is minimized. The purpose of this article is to present a technique that combines atomic force microscopy and orientation imaging microscopy to measure grain surface topography during in-situ tensile testing.