Mechanical mixing induced by sliding wear of an Al–Si alloy against M2 steel

Abstract

The microstructural characteristics of worn surface of Al–Si alloys sliding against a tool steel has been investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS) and X-ray mapping. In particular, mechanical mixing phenomenon induced by the sliding wear between the materials in sliding contact has been extensively studied at a variety of sliding loads. The features of the mechanically mixed layers (MML) in the worn surfaces are also related to those of wear debris generated from the sliding systems. The results show that the mixed layers and wear debris have similar microstructural features and are comprised of mixtures of ultrafine grained structures, in which the constituents vary depending on the sliding loads. At a low load, the ultrafine structures mainly consist of the original base materials, i.e., α-Al solid solution and α-Fe from the steel. With an increase in sliding load, the ultrafine structures are incorporated with Fe–Al(Si) intermetallic compounds and aluminum oxides. The formation mechanisms of the mechanically mixed layers and their influences on wear mechanisms of these multiphase materials are studied based on the microstructural observations.