Influence of Alloy Composition on Cast Cracking and Heat Resistance of Mg-Al-Ca Cast Alloy

Magnesium alloys are important materials since they can be used to significantly reduce the weight of automobiles, but their application has been limited thus far. One possible way to extend the usage of magnesium alloys is applying them to peripheral parts of the engine that are large, have complicated shapes, and are exposed to high temperatures under the loaded condition. However, heat-resistant magnesium alloys always have poor castability, since such alloys have a lot of intermetallic compounds with poor ductility.In this study, hot cracking tests of Mg-Al-Ca cast alloys were performed in a high-pressure die-casting machine using a die with an I-shaped cavity to investigate the castability. At the same time, the heat resistance of the cast alloys was evaluated using a bolt load retention test. It was found that adding tin to heat-resistant Mg-Al-Ca improved its hot cracking behavior without reducing its excellent heat resistance.