Increase of Mechanical Strength of a Mg85Zn12Ce3 Amorphous Alloy by Dispersion of Ultrafine hcp-Mg Particles

A Mg85Zn12Ce3 amorphous alloy containing finley dispersed hcp-Mg particles was found to form either by melt spinning or by heat treatment of the melt-spun ribbon. The particle size and interparticle distance of the hcp-Mg phase can be controlled in the range of 3 to 20 nm and 5 to 10 nm, respectively. The mixed phase alloy prepared thus has a good bending ductility and exhibits a high ultimate tensile strength (σB) ranging from 655 to 935 MPa and a fracture elongation including elastic elongation (εf) of 2.9 to 7.0%. The highest specific strength (σB/density=σs) reached 3.6×105 N·m/kg. It should be noted that the highest values of σB, σs and εf are considerably higher than those (690 MPa, 2.5×105 N·m/kg and 2.5%) for amorphous Mg–Zn–Ce alloys. The increase of the mechanical strengths by the formation of the mixed phase structure is presumably due to a dispersion hardening of the hcp supersaturated solution which has the hardness higher than that of the amorphous phase with the same composition.