Mechanical and thermophysical properties of Mg-Al-RE alloys produced by different casting technologies : A comparison study

Sammanfattning

Magnesium alloys are highly valued in automotive, power tools, and consumer applications due to their excellent strength-to-weight ratio. However, their performance is highly sensitive to processing conditions. This thesis investigates how different casting processes influence the microstructure, mechanical behavior, and thermophysical properties of AE44 magnesium alloy.Two processing routes are compared: high-pressure die-casting (HPDC) and directional solidification using a Bridgman furnace, which simulates the microstructure of manufacturing technologies with a slow solidification rate, such as sand-casting. The experimental work includes tensile tests at room and elevated temperatures, thermal properties characterization, and short-duration creep tests.The results indicate that directional solidification at a slow cooling rate negatively impacts mechanical performance, introducing significant variation in alloy behavior, likely due to texture effects. In contrast, HPDC consistently results in superior mechanical properties. However, the thermal properties measured in this study appear to have low sensitivity to the choice of casting technology.Overall, the present work demonstrates how different casting processes can significantly affect the performance of a selected alloy, highlighting the importance of considering the relationship between process microstructure and final properties.