Structure and wear of Al surface layers reinforced with AlCuFe particles using ultrasonic impact peening: Effect of different particle sizes

Near-surface layers in aluminium specimens are modified using quasicrystalline (QC) AlCuFe particles introduced into a zone of severe plastic deformation induced by ultrasonic impact peening (UIP). Two types of QC particles are used: atomized with average size of approx. 25 μm (coarse QC–c-QC) and milled — 0.3–0.5 μm (fine QC–f-QC). The effect of QC particles of different sizes on microstructure and wear resistance of sub-surface composite layers in aluminium is studied in this paper. XRD, SEM and TEM studies of reinforced aluminium layers allow establishing the links between microstructural features of the layers and their sliding wear. The formed layers of composites reinforced with both types of QC particles demonstrate almost double increment in wear resistance when compared to that of annealed aluminium. It is due to the combination of several factors: (i) high hardness and high wear resistance of QC reinforcement (more efficient for c-QC); (ii) relatively strong interfacial bonding of homogeneously dispersed reinforcing QC particles; (iii) fine grain structure of the Al matrix (f-QC) or increased density of dislocations arranged in fine dislocation-cell structure (c-QC) — i.e. increased volume fraction of grain boundaries/dense dislocation walls. ► AlCuFe particles reinforced composite layers in Al. ► Ultrasonic impact peening enables uniform dispersion of reinforcements in the Al matrix. ► Sufficiently strong interfacial bonding promotes increase in wear resistance. ► Formed sub-structure or nano-sized grain structure enhances wear and microhardness. ► Double growth in wear resistance of reinforced surface layers is observed.