High Strength Nanocrystalline Mg-Al-Ca Alloys Produced by Rapidly Solidified Powder Metallurgy Processing

Abstract

Nanocrystalline magnesium alloy having high specific tensile strength, high Young's modulus, high elevated-temperature tensile strength, high-strain-rate superplasticity and high corrosion resistance has been developed by rapidly solidified powder metallurgy (RS P/M) processing in amorphous forming Mg 70 Al 20 Ca 10 alloy. The density of the nanocrystalline RS P/M alloy was 1.80 g/cm 3 . The compressive yield strength and plastic strain that were dependent on the consolidation temperature were in the ranges of 570 to 930 MPa and 0.5 to 9.2 %, respectively. The tensile yield strength, plastic elongation and Young's modulus of the RS P/M alloy extruded at 673 K were 600 MPa. 1.0% and 50 GPa, respectively, The specific tensile yield strength was four times as high as that of a commercial AZ91-T6 alloy. The RS P/M alloy exhibited excellent elevated-temperature yield strength that was 360 MPa at 473 K. The RS P/M alloy also exhibited superplasticity at a high strain rate of 1. 1x10 0 S -1 and at 723 K. It is expected that the Mg 70 Al 20 Ca 10 RS P/M alloy is applied in some fields that requires simultaneously the high specific strength at ambient and elevated temperatures, high workability and high corrosion resistance.