Microstructure and Mechanical Properties of ZA27 Alloy Matrix Composites

摘要

The effect of Al_2O_3 and SiC particles on microstructure and strength (compressin) of ZA27 (zinc-based alloy) was studied. Two composites were produced by compocasting process, i.e. particles of strengtheners were continuously added to the semi-solid melt which was vigorously stirred. The concentration and size of strengtheners were approximately the same, i.e. 3wt.percent and 15mum, respectively. Comparative investigations of microstructure (optical and scanning electron microscope) and compression strength (from room temperature to 170 deg C) of composites and the corresponding as-cast alloy, produced by standard melting and casting process, were carried out. The dendritic structure was nearly completely removed by compocasting process, whereas a rather inhomogeneous distribution of strengtheners (particularly Al_2O_3) in the matrix was achieved. The strength of both composites was superior to that of as-cast alloy, the difference being greater with increase in temperature. The effect of Al_2O_3 and SiC particles on matrix strengthening was approximately the same.