Characterization Of The Mechanical Performance Of The AE44-2 And AE44-4 High Pressure Die Cast Mg-Rare Earth Alloys

B. Fu


This thesis aims to study the local mechanical properties of high pressure die cast (HPDC) AE44-2 and AE44-4 alloys at 25˚C and 200˚C and their microstructures. The chemical composition of the precipitates and grain size, the effect of cooling rate on the grains, the relationship between the grain size and mechanical properties, and the creep resistance of these two HPDC alloys were studied and discussed. In this thesis, the spherical micro-indentation, constant Berkovich indentation tests, and tensile tests were performed on the specimens at 25˚C and 200˚C to probe their stress- strain response and creep behavior. This study used a new analytical technique to deduce the stress-strain curves from the spherical indentation tests. This thesis suggests that the mechanical properties of these two alloys have a complicated dependence on the grain size. Although, with different RE additions, these two alloys have a similar indentation creep resistance at 25˚C and 200˚C. Keywords: