Effect of rare-earth additions on the microstructure and mechanical properties of die-cast mg alloys AE44-4 and AE44-2

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The magnesium alloy AE 44-4 is designed for use at elevated temperature, up to about 200°C, but is more expensive, and thus less competitive, than steel and aluminum alternatives. This arises because the good high-temperature mechanical properties of AE 44-4 result from the addition of up to 4% rare earth elements. A relatively new version of the alloy, AE44-2, is a lower cost formulation but its elevated temperature performance has not been thoroughly investigated. By conducting laboratory scale controlled casting trials, characterizing microstructure, and probing mechanical behavior at the micro-scale we will quantify and report on the relationships between solidification conditions and as-cast microstructures and generate a microstructure- and temperature-dependent mechanical property dataset for the elevated temperature properties of the AE44-2 and the AE44-4 Mg alloys. These results will subsequently be incorporated into the research team's Integrated Computational Materials Engineering (ICME) models, thus enabling our industrial partner, Meridian Lightweight Technologies Inc. (Strathroy, ON) to make realistic predictions of the spatially varying, high-temperature mechanical performance of high pressure die cast AE44-2 and compare these to similarly die cast AE44-4 and other common die cast magnesium alloys.Successful completion of this research project will give our industrial partner improved competitiveness over other Mg suppliers and other materials through improved casting optimization capability and the ability to shorten the AE44-2 product development cycle.