LIGHT-METAL BASE AMORPHOUS-ALLOYS CONTAINING LANTHANIDE METAL

Light-metal base amorphous alloys with high specific strength and good corrosion resistance were produced in Al- and Mg-based systems containing lanthanide (Ln) as an essential solute element for glass formation. The amorphous alloy systems were composed of Al-Ln, Al-Ln-TM, Mg-Ln, Mg-Ca-Ln and Mg-Ln-TM (TM = transition metal). The addition of TM was very effective for the extension of their glass formation ranges. The highest tensile strength (sigma(f)) reaches 1250 MPa for the Al-based alloys and 830 MPa for the Mg-based alloys. The Mg-based alloys have a large glass-forming capacity which enables the production of an amorphous phase by a metallic mold casting method. The extrusion of the Al-based amorphous powders at temperatures above crystallization temperature caused the formation of high strength materials with finely mixed structure consisting of dispersed intermetallic compounds in an Al matrix. The highest values of sigma(f) and the fatigue limit are as high as 940 and 330 MPa, respectively, at room temperature and 520 and 165 MPa at 473 K. The extruded Al-Ni-Mm alloys have been used as machine parts and subsequent further development as practical materials is expected.