Metallic Glasses
Metallic glasses/ amorphous metals were originally produced in thin sections by rapid cooling or deposition techniques. They found commercial application in transformers as a replacement for Fe-Si. Japanese and American scientists then developed so-called BMGs (bulk metallic glasses) starting in the 1980s that utilize different atomic sizes of the constituent elements in the alloys to prevent ordering and reducing the requisite cooling rates down to as low as 1 K/s. The metallic glasses have high strength, high hardness and corrosion resistance. (The latter two properties are valuable in coatings, which is a more established application area for amorphous metals.) Metallic glasses also have high elastic limit, which is beneficial for energy transfer in sporting goods like rackets and baseball bats. The BMGs are also easy to mold since they soften gradually at relatively low temperatures (typically 400-600°C) akin to thermoplastics. However, the fundamental weakness has been lack of ductility and brittle fracture of the bulk material. However, recent development of BMGs that grow crystalline dendrites has produced materials with remarkable strength and toughness, and opens the door to structural applications in areas like aerospace. We report on this as well as other recent developments in materials and applications, and also cover recent scientific efforts in simulation and modeling of metallic glasses.
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