Wear behavior of thixoformed AZ91D magnesium alloy: A comparison with permanent mould cast alloy

The friction and wear properties of thixoformed (TF) and permanent mould cast (PMC) AZ91D magnesium alloys were investigated under dry reciprocating sliding conditions. The results indicated that the wear resistance of the TF alloy was significantly superior to that of the PMC alloy. This was attributed to that the thixoforming process obviously decreased the amount of porosity and grain size, and enhanced solid solution strengthening. The wear mechanism of both alloys showed similar tendency to change from mild wear regime (oxidation wear and/or micromachine wear) to severe wear regime (plastic deformation induced wear or/and severe plastic deformation accompanied by severe adhesive wear) with increase in reciprocating frequency or load. However, the wear of the TF alloy was always milder than that of the PMC alloy under each wear regime. The effect of wear mechanism on the friction coefficient was larger than that of the wear rate. (c) 2006 Elsevier B.V. All rights reserved.