Nanocomposites can be produced by partial crystallization of bulk metallic glasses (BMG). The introduction of such nanocrystals in an amorphous matrix can sharply change the mechanical behavior of the glass at room temperature. In the present study, the effect of crystals in Mg-based BMG is studied by partial crystallization of the Mg65Cu25Gd10 and addition of 3 at.% of iron. Various techniques (DSC, DRX, TEM) are used to get data about the nature, the volume fraction or the average size of the crystals. Mechanical properties at room temperature are investigated in compression. The fracture stress is enhanced by iron addition, but no favorable effect of partial crystallization is observed for the Mg65Cu25Gd10 BMG. These results are discussed in relation with the associated microstructures

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Various Mg based BMG were successfully elaborated by copper mould casting. High strengths (> 600 MPa) were obtained in compression at room temperature associated with a large elastic strain (≈ 0.015) but also to a macroscopically brittle behavior. Deformation capacity in the glass transition interval has been investigated. For such temperatures, thanks to Newtonian rheologies, glasses exhibit a particularly good viscoplastic forming ability with low viscosities. However, in some cases, crystallization can occur during the process and increase sharply the viscosity.