Connecting, assemblage and electromechanical shaping of bulk metallic glasses

Abstract

Shaping of Bulk metallic glasses (BMG) and BMG-based composites into various complex forms has been achieved by a new electromechanical process. Bulk metallic glasses have large supercooled regions between the glass transition temperature Tg and the crystallisation temperature Tx up to some hundred degrees higher. In this range, the undercooled liquid in principal deforms in a Newtonian way, allowing thermomechanical shaping in the low viscosity range as applied to oxide glasses. Electromechanical shaping technology allows rapid shaping at low applied stresses by eliminating the thermal mass of the furnace and the need to heat the deformation dies. Joule heating is efficiently used thanks to the high electrical resistivity of bulk metallic glasses. Here it is shown that large shape changes (high deformations) can be achieved without crystallisation. For example, crosses and other mechanically resistant complex forms are achieved from two amorphous rods or an amorphous rod and a crystalline bar.