Chapter 12 – Creep in Amorphous Metals

Amorphous metals are a relatively new class of alloy, originating in about 1960 with the discovery of thin metallic ribbons by splat cooling. These are always alloys, and pure metal glasses have not yet been produced. Because these alloys are noncrystalline, they have no dislocations, at least in the sense normally described in crystalline materials. Thus, amorphous metals have yield stresses that are higher than those of crystalline alloys. High fracture stress, low elastic moduli, and sometimes-favorable fracture toughness are observed. Often, favorable corrosion properties were observed, as well, partly due to an absence of grain boundaries. Toward 1990, alloys with deep eutectics were developed that allowed liquid structures to be retained in thicker sections in the amorphous state on cooling to ambient temperature. With this development, there has been fairly intensive study of bulk metallic glasses for possible structural applications. Most of the alloys in this chapter are relevant to bulk metallic glasses.