Effects of processing parameters on wear behaviors of thixoformed AZ91D magnesium alloys

The effects of processing parameters on the wear behaviors of thixoformed AZ91D alloys were investigated under dry reciprocating sliding conditions. The results indicated that the processing parameters did not change the dominative wear mechanism but obviously affected the wear rate. The wear rate increased with the increase in reheating duration or mould temperature. There was an optimal reheating temperature of 858 K, and the wear rate would increase if the temperature was lower or higher than 858 K. These changes in wear rate were attributed to the hardness values of the formed alloys which depended on the processing parameters and the resulting microstructures. The parameters did not remarkably affect the friction coefficient because the dominative wear mechanism always maintained micro-machining under the present conditions. However, the parameters altered the attribution of the subsidiary wear mechanism of adhesion to the whole wear. Comparatively, the effect of the mould temperature was larger than those of the reheating time and reheating temperature. In addition, the wear behaviors of different positions in one thixoformed product were also different because its microstructure was quite inhomogeneous.