Authors
School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran
Abstract
Friction stir processing was carried out on an AZ31 substrate with and without introduction of nano-sized TiC powder. Clusters of TiCwere found in the fabricated layer with a non-uniform distribution. Applied additional passes resulted in gradual break-up of TiC clusters; a nano-composite layer with a uniform dispersion of nano-sized TiC reinforcements in a matrix of fine grains (~3mm) was achieved after three further passes. This layerexhibited a micro hardness and yield strength of ~91HV and 290MPa, respectively. These values are found to be ~1.5 and 1.3 times of those of the as-received AZ31 substrate, respectively.Enhancement of mechanical properties is attributed to dispersion of nano-sized hard reinforcements in a matrix of fine grains. The layer produced without introduction of TiC powder showed a microstructure of fine grains (~5.5mm). However, it exhibited a lower micro hardness and yield strength than those of the as-received AZ31; this softening is related to dissolution of an intermetallic compound phase during the thermo-mechanical phenomena associated with friction stir processing.
Keywords
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