Grant: Collaborative Research and Development Grants

In this proposed project, in collaboration with GM of Canada, we will develop thermodynamic, phase equilibrium and reaction models to better understand the phase relations in the microstructure, the forming properties and phase reactions during processing, casting and hot rolling of Mg alloys dedicated to automotive applications. These computational thermodynamic models will predict with the FactSage software the stable phase proportions and compositions, the metastability of non-stable phases, and the most stable products of reactions involving Mg-alloys with very reactive alloying elements such as Al, Ca, Sr, and the rare-earths, and with processing tools. This will be done using thermodynamic modeling, where Gibbs energy expressions are developed: the parameters of such functions are calibrated by complex optimization techniques using published literature data (phase equilibrium, activity, enthalpies), experimental DSC, DTA, XRD and diffusion couples data obtained during this project, and First Principles calculations of enthalpies of formation of compounds and partial enthalpies of important solutes in solid solution. The proposed project will extend the thermodynamic modeling of Mg alloys, with the additional feature of estimating missing data from First Principles calculations for stable and metastable phases, for the following important systems (4 sub-projects): 1)Mg-Al-Li-Zn-Mn, 2) Mg-Al-Rare earths-(Mn), 3) Grain refiners (Ti, C, B, Zr) and 4) Mg-Al-Zn-Ca-Sr-(Mn). In addition, we will use the databases to predict proportions and compositions of phases present in the Mg alloys obtained by twin roll casting (TRC) and hot rolling (HR) at CANMET. The databases will be used to guide CANMET researchers in selecting the best alloy composition and the best annealing temperatures according to the desired phase distribution. This forms the 5th sub-project: Calculation of stable and metastable phases in TRC + HR of Mg alloys.