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

The microstructural characteristics of worn surface of AI-Si alloys sliding against a tool steel has been investigated using scanning electron microsc opy (SEM) and transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS) and X-ray mapping. In particular, mechanical mixing phe nomenon induced by the sliding wear between the materials in sliding contac t has been extensively studied at a variety of sliding loads. The features of the mechanically mixed layers (MML) in the worn surfaces are also relate d to those of wear debris generated from the sliding systems. The results s how that the mixed layers and wear debris have similar microstructural feat ures and are comprised of mixtures of ultrafine grained structures, in whic h the constituents vary depending on the sliding loads. At a low load, the ultrafine structures mainly consist of the original base materials, i.e., a lpha-Al solid solution and alpha-Fe from the steel. With an increase in sli ding load, the ultrafine structures are incorporated with Fe-Al(Si) interme tallic compounds and aluminum oxides. The formation mechanisms of the mecha nically mixed layers and their influences on wear mechanisms of these multi phase materials are studied based on the microstructural observations. (C) 1999 Published by Elsevier Science S.A. All rights reserved.