MICROSTRUCTURAL EVOLUTION OF TiC PARTICULATE REINFORCED Mg-13.5Al-0.6Zn MATRIX COMPOSITE DURING PARTIAL REMELTING

摘要

Microstructural evolutions during partial remelting of Mg-13.5Al-0.6Zn alloy and TiC/Mg-13.5Al-0.6Zn composite are investigated by the isothermal treatment at the temperature of 510℃. Compared with the unreinforced matrix alloy, the remaining liquid dramatically decreases in the composite; furthermore, also the solid α-Mg grain size in the composite significantly reduces in the partial remelting microstructure. The addition of cerium (Ce), which is combined with Al to form AlxCe compounds during solidification, has little contribution to the entrapment of TiC by the α-Mg grains during partial remelting process. As a result, in addition to very small amount of them eventually entrapped within the α-Mg grains, most of the TiC particulates are present in the remaining liquid phases distributing at the grain boundaries after partial remelting process.