Mechanical properties of SiC particle–AZ31B magnesium alloy machined chips composites prepared by hot extrusion after ECAP

Abstract

Wear resistance and mechanical properties of hot extruded AZ31B/SiC particle composite, where the hot extrusion billets were processed by ECAP, were investigated. Uniform dispersion of SiC particles was observed after extrusion for the mean particle size of 1.2ϳ11 mm constituting 0 to 6% volume fraction of SiC particle content, where the particles had been thinly adhered to the surface of the machined chips of ECAP-hot extrusion samples before extrusion. However, when the SiC particle size is under 3 mm, the aggregates at the triple junction of the interfaces of the machined chips could not be decomposed and dispersed. To solve this problem, hot extrusion was carried out using various cold green compacts prepared by repetitive ECAP processed up to 7 times. As a result, refinement of grain size was obtained for the ECAP extruded materials by decomposition and dispersion of the SiC particles with increase in the ECAP frequency. Consequently, it was possible to obtain the composite of AZ31 magnesium base alloy machined chip and SiC particle which contains almost uniformly dispersed SiC particles. Furthermore, the average grain diameter of the matrix was very much refined to approximately 2 mm, and s B , s 0.2 were also improved. Frictional wear test shows that abrasion resistance was further improved for Nϭ7 extruded materials than Nϭ4 samples due to more homogeneous mixing of the SiC particles as well as decomposition and dispersion of the aggregates.

Solid-state recycling of aluminium alloy swarf through cold profile extrusion and cold rolling

“…Although the studies mentioned above have targeted single-phase materials, the solid-state recycling of machined chips into composite materials has also been attempted. These have included magnesium-based composites with SiC particles (Aida et al, 2008) and aluminium-based composites with reinforcing particles such as tungsten, which was adopted by Gronostajski et al (1996), and SiC, which was utilised by Tekkaya et al (2009). It was recently revealed that the hot extrusion of aluminium alloy machined chips with pure aluminium powder added as a binder achieves better bonding and results in improved mechanical properties for recycled products made from two-phase materials (Sherafat et al, 2009).…”