Properties of Mg-Y-Cu glasses with nanocrystalline particles

Nanocrystals embedded in an amorphous Mg-Y-Cu phase can lead to an increase in fracture stress compared to the homogeneous amorphous alloy. Therefore, mechanical alloying of elemental Mg, Y and Cu powders with Si-, Ce-, Y2O3- and MgO-additives was used to prepare amorphous/nanocrystalline phase mixt ures. Despite the existence of nanocrystalline particles in the amorphous m atrix, all samples exhibit a temperature difference Delta T-x (= T-x - T-g) between the crystallization temperature T-x and the glass transition tempe rature T-g of about 50 - 60 K and a decrease of viscosity above T-g The add itives enhance the thermal stability of the amorphous Mg-Y-Cu phase. Bulk a morphous/nanocrystalline samples can be prepared via consolidation and subs equent hot working in the viscous state above T-g. Finally, first results o n the mechanical properties of the samples are presented. (C) 1999 Acta Met allurgica Inc.