MG-BASED AMORPHOUS-ALLOYS

Recent progress in Mg-based amorphous alloys has been reviewed in the framework of the results obtained by the present authors. The amorphous alloys are formed in wide composition ranges in a number of Mg-based alloy systems by melt spinning. The amorphous alloys in Mg-Ln-TM (Ln drop lanthanide metal, TM drop transition metal) system exhibit a wide supercooled liquid region before crystallization and have large glass-forming ability which enables the production of bulk amorphous alloys with thicknesses below 7 mm by the high pressure die casting process. The bulk amorphous alloys were also found to exhibit high tensile strength above 600 MPa. Furthermore, by using the newly developed high pressure argon atomization equipment in which oxygen and moisture contents can be controlled to be below 1 ppm, Mg-based amorphous powders were produced in various alloy systems. The consolidation of the Mg-based amorphous powders resulted in finely mixed structures of Mg and compounds. The mixed phase alloys exhibit high tensile strengths at room and elevated temperatures for Mg-Cu-Y and Mg-Ca-Al alloys and high corrosion resistance for Mg-Ca-Al alloys. The large glass-forming ability and these excellent properties for the Mg-based amorphous alloys are very attractive in applications for the subsequent development of the new alloys.