Assessing capabilities of Thixomolding system in semisolid processing of magnesium alloys

摘要

Mg-9Al-1Zn alloy, in the form of mechanically comminuted chips, was processed using a Thixomolding system within the semisolid state temperature range. The influence of operating parameters on mould filling characteristics, integrity and the microstructure of components with varying geometry and wall thickness was examined. It was revealed that the temperature profile along the material flow path is a key factor which controls the process. Although α-Mg and Mg{sub}17Al{sub}12 of random crystallographic orientation was the common phase composition, the microstructures generated by each thermal profile were morphologically unique. The unmelted phase of globular morphology promoted uniform flow; however, even when unmelted phase was present at high contents, the mould was filled irregularly unless the injection velocity was adjusted accordingly.