Chemical Properties of Amorphous Metals

Abstract

Researchers have been taking a considerable interest recently in the characteristics of amorphous metallic materials. This is because their ex­ tremely disordered atomic arrangements contribute to various pro­ perties different from those of crystalline metals, which have a long-range ordered structure. It has been known since the 1950s that such a random atomic structure can be produced by vacuum vapor deposition and chemical depo­ sition techniques. The most important discovery in the preparation of amorphous metals was made in 1960 by Duwez et al (1), who demon­ strated that the molten eutectic Au-Si alloy could be caused to solidify in the amorphous state by the Gun technique at a cooling rate of about 106oC sec 1. Since then, many kinds of amorphous metals have been found in metal-metalloid and metal-metal systems by this rapid quenching technique. The early investigations of these alloys concentrated on structure, and on magnetic and electrical properties, due mainly to the fact that the specimens obtainable were very small and irregular in shape. The sub­ sequent development of new quenching techniques (2-4) in 1970 facilitated the study of amorphous metals by making it possible to produce sizable specimens uniform enough for more quantitative measurements. As a result, the physical, mechanical, and chemicalproperties of amorphous metals have been characterized. The present authors and co-workers have been investigating these properties since the end of 1960s, and have re­ ported that amorphous metals exhibit high strength and toughness, and that some metals with selected compositions have extremely high cor­ rosion resistance and/or excellent magnetic permeability (5).