Bulk metallic glasses

In the last decade metallic glasses have regained considerable interest due to the fact that new glass-forming compositions have been found that have a critical cooling rate of less than 100 K/s and can be made glassy with dimensions of I cm or more. The development of such alloys with a very high resistance to crystallization of the undercooled melt has opened new opportunities for the fundamental study of both the liquid state and the glass transition. The availability of bulk specimens has enabled measurements of various physical, particularly mechanical, properties that were previously impossible. Furthermore, these alloys are progressively being used for engineering applications. In order to recognize this significant advancement in materials science, this new class of materials is commonly referred to as bulk metallic glasses. This article will first review the history of metallic glasses. The origins of glass formation are then discussed and thermophysical properties (crystallization, phase separation, viscosity and diffusion) are presented. Furthermore, the paper outlines magnetic and mechanical properties along with resulting applications and presents a new processing technique to discover bulk metallic glass compositions in Section 5. (C) 2003 Elsevier Science Ltd. All rights reserved.