Abstract
Rapidly solidified flakes of Mg–Y based alloys with or without ternary additions of Ca and Zn were prepared by atomizing the alloys melt and subsequent splat-quenching onto a single copper roll. Ternary alloying additions were 3 mass% Ca for Mg–5 mass% Y alloy and 2 mass% Zn for Mg–10 mass% Y alloy. The flakes were consolidated by cold pressing and hot extrusion. In as rapidly solidified flakes of the Mg–Y binary alloys, extended solid solubility of Y was obtained in the Mg matrix because of high cooling rate of rapid solidification. But, fine dendric structures, the arm spacing of which was approximately 4 μm, were observed in rapidly solidified flakes of the ternary alloys. After consolidation, fine dispersion of intermetallic compounds was observed in all the extruded P/M materials. Those compounds consisted of Mg24Y5 in binary alloys, and Mg24Y5, Mg2Ca or Mg12YZn in the ternary alloys. As-extruded P/M materials of Mg–10 mass%Y and Mg–10 mass%Y–2 mass%Zn alloys showed no remarkable softening after annealing at 573 K. Mg–10 mass%Y–2 mass%Zn alloy showed the highest tensile strength of 520 MPa at room temperature and 440 MPa at 473 K. However, the tensile strength of all the P/M materials dropped below 80 MPa at 573 K.
