Thermodynamic modeling and experimental investigation of glass-forming magnesium alloys

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Development of a reliable Mg database that contains all the possible alloying elements is the applicant's long term objective. This will be achieved through computational thermodynamics coupled with key experiments using DSC, XRD, SEM/EPMA and diffusion-couples techniques. This proved to reduce the time and effort necessary to establish such a multicomponent database. The current proposal focuses on investigating Mg ternary systems that have strong potential for metallic glass applications. Three of such systems are Mg-Al-Y, Mg-Ni-Y and Mg-Cu-Y. Mg-based glass-forming alloys have attracted special attention due to their low-density, high strength, excellent corrosion resistance, and high toughness. Mg-based metallic glasses exhibit high tensile fracture strength which is more than twice as high as the highest strength of conventional Mg-based crystalline alloys. More importantly, it is mentioned in the literature that Mg-based alloys have the potential to produce the largest bulk metallic glass. So far, the efforts worldwide are focussed on the improvement of the glass-forming ability of Mg-based alloys by additions of different alloying elements. The current proposal aims at contributing to these efforts by providing a self-consistent thermodynamic database that can be used to identify the most promising compositions for Mg-alloys that have the highest glass-forming ability. Unlike the current practice of trial and error method, in the proposed research, the compositions that have the tendency to form bulk metallic glasses will be identified using this database. This can be obtained through identifying the compositions that exhibit low lying liquidus surface. It is worth noting that this strategy will enhance the chance of obtaining the most suitable Mg-based alloys for bulk metallic glass applications instead of the traditional empirical trial and error experimentation. Further, the proposed strategy will enable predicting the composition sensitivity of the glass-forming ability which is not possible by the existing criteria that are based on atomic size distribution. This project will benefit Canadian automobile and aerospace industries and will provide new opportunities to all Mg products producers.