The influence of stacking fault energy and adhesion on the wear of copper and aluminum bronze

Abstract

The subsurface deformation induced in pure copper and a series of Cu-Al alloys has been characterized using scanning electron microscopy after prolonged dry sliding contact against an Al 2O 3 cylinder. Scanning electron microscopy was found to be a very useful technique for examining the deformation in depth. The strength of the adhesive bond between copper and Al 2O 3 was found to be less than the cohesive strength of either material. Therefore true transfer layers were not formed. Owing to dynamic recrystallization occurring near the surface, extremely large strains ( i.e. greater than 12) were sustained and resulted in very low wear rates in agreement with the results of Bill and Wisander. A mechanically mixed layer, which is continuous with the substrate and incorporates oxide particles, was observed. Two mechanisms were identified for the production of wear debris. The layered structure proposed by Heilmann to explain the random misorientation of subgrains was confirmed. The adhesive strength of the Cu-Al alloys examined with Al 2O 3 was greater than the cohesive strengths of the alloys. Therefore metal transfer to the slider occurred. The subsurface deformation behavior of aluminum bronze was found to be very dependent on both the stacking fault energy (SFE) and the orientation of individual grains and is related to the wear rate. In the case of aluminum bronze sliding against A1 2O 3, adhesion effects overshadow the influence of SFE. However, in other systems, it is expected that SFE effects will play a dominant role in determining wear response.