Structure and mechanical properties of Mg₈₅Cu₅Zn ₅Y₅ amorphous alloy containing nanoscale particles

The application of melt-spinning process of Mg₈₅Cu ₅Zn₅Y₅ alloy was found to cause the formation of a mixed structure consisting of nanoscale crystalline particles embedded in an amorphous matrix. The Mg₈₅Cu₅Zn₅Y ₅ (at.%) alloy has a mixed structure consisting of amorphous+hcp-Mg in the as-quenched state and amorphous+hcp-Mg+Mg₂₄Y₅ in an annealed state at 544 K for 300 s. The crystallization of the mixed phase alloy occurs through two stages of Am.(amorphous) → Am. + hcp-Mg → hcp-Mg + Mg₂₄Y₅. The particle size is as small as 10-30 nm in the as-quenched state and 20-40 nm in the annealed state, respectively. The tensile strength for Mg₈₅Cu₅Zn₅Y₅ alloy at 298 K is 467 MPa, being nearly twice as high as that (242 MPa) for a conventional crystalline AZ91(Mg-9wt.%Al-1wt.%Zn) alloy prepared at the same melt-spinning condition. Both of the ribbons exhibit good bending ductility. The high mechanical strength of the Mg₈₅Cu₅Zn ₅Y₅ alloy is presumably due to the formation of the fine mixed structure consisting of nanoscale particles embedded in the amorphous matrix. These data allow us to expect the future progress as a new type of high specific strength material which can be fabricated with industrialization method.