Ａｌ‐Ｍｇ‐Ｓｉ系高濃度合金の急冷凝固Ｐ／Ｍ材の組織と機械的性質

Abstract

Rapidly solidified P/M materials were prepared for Al–Mg–Si ternary alloys of nine different compositions with higher alloying additions than the commercial Al–Mg–Si alloys. The rapid solidification was performed by argon gas atomization and subsequent splat quenching on a water-cooled copper roll. The rapidly solidified flakes were consolidated to P/M materials by cold pressing, vacuum degassing and hot extrusion at 673 K with a reduction of 25:1. Cast ingots of these alloys were also hot-extruded under the same conditions to the I/M reference materials. For all the tested alloys, tensile strength of the as-extruded P/M materials is higher than that of the I/M counterparts. The tested alloys were grouped into two classes according to the changes in hardness and tensile strength of the P/M materials with increasing Mg+Si content. The alloys containing excess Mg to the Mg2Si composition showed higher hardness and tensile strength than those without excess Mg at the same Mg+Si content. It is considered that both Mg solid solution and dispersion of Mg2Si particles were contributing to the strength increases in the P/M materials. The mechanical properties at room temperature were highest for the P/M material of Al–13%Mg–4%Si alloy which showed tensile strength of 516 MPa, specific modulus of 44.7 GPa/g/cm3 and specific strength of 204 MPa/g/cm3.