Shaping, joining and engraving of bulk metallic glasses using an electromechanical process

Some intrinsic materials properties of bulk metallic glasses (BMG) such as electrical resistivities two orders of magnitude higher than good conductors and a Newtonian viscous-flow regime of deformability have allowed shaping, joining and engraving of BMGs using a new electromechanical process. The new process exploits the fact that bulk metallic glasses have large liquid supercooled regions between the glass transition temperature T, and the crystallisation temperature T,. In this range, the undercooled liquid in principle deforms in a Newtonian way, allowing thermomechanical shaping in the low viscosity range as applied to oxide glasses. Electromechanical processing technology has been used for rapid shaping at low applied stresses by eliminating the thermal mass of the furnace and the need to heat the deformation dies. The process parameters has been adapted to fully maintain the glassy state or, when desired in appropriate compositions, to induce nanocrystallisation or nano-quasicrystallisation during the joining or shaping operation.