Abstract
Recently, a number of amorphous alloys having a temperature range of supercooled liquid above 50K before crystallization and high glass-forming ability have been discovered. The new amorphous alloys are called "bulk metallic glasses". Such metallic glasses can be fabricated from the melt in a bulk form with a thickness of-10mm at slow cooling rates of the order of 1-100 K/s. The metallic glasses, moreover, exhibit useful properties such as high strength and high stiffness at ambient temperature. We have found that the metallic glasses exhibited high-strain-rate superplasticity at temperatures above the glass transition temperature. The superplasticity inherent in the supercooled liquid seems to give a unique approach for the synthesis of bulk metallic glasses by powder metallurgy processing. We, therefore, tried to consolidate the metallic glass powders using the superplasticity. We consequently succeeded in synthesis of bulk metallic glasses with the same tensile strength as the cast bulk glassy alloy and melt-spun metallic glass ribbon. Recently, the bulk metallic glasses produced by extrusion of gas-atomized glass powders have been commercially used as a face material of newly designed "iron"-type and "patter"-type golf club heads.
