The micro-formability of Zr-based amorphous alloys in the supercooled liquid state and their application to micro-dies

Zr-based amorphous alloys exhibit an obvious glass transition phenomenon and supercooled liquid state over a wide temperature range. In the present paper, the authors study the macroscopic and microscopic deformation behavior of Zr-Al-Cu and Zr-Al-Cu-Ni amorphous alloys. On a macroscopic scale, the materials exhibit a Newtonian viscous flow in the supercooled liquid state. To evaluate the microformability of the materials, the authors developed an evaluation system using a micro-V-grooved die made of (1 0 0) silicon that has been processed by electron beam lithography and anisotropic etching and employed this system to quantitatively evaluate the microscopic formability of the materials. The V-groove is from 1 to 20 mum wide and has a base angle of 70.6 degrees. The material was subjected to the newly developed micro-forging apparatus and was die forged with micro-V-grooved dies. After the deformation, the shape of the specimen was measured using a three-dimensional shape measurement system with a highly sensitive detector in a scanning electron microscope. These geometrical analyses of deformed specimens confirmed the superior formability on a micrometer scale and indicated the possibility of fabricating very fine micro-parts such as those for micro-electro-mechanical systems (MEMS). Furthermore, the material is stable under the glass transition temperature T-g, and can thus be used as a fine micro-forging die for some plastic materials or other amorphous alloys with a glass transition temperature below T-g. In the present paper, it was confirmed that Zr-Al-Cu amorphous alloy could be used as a micro-die for forming La-Al-Ni amorphous alloy. As a result, it was demonstrated that amorphous alloys are potential micro-materials for fabricating various micro-parts or micro-dies because of their superior mechanical characteristics and homogeneity on a microscopic scale. (C) 2001 Elsevier Science B.V. Ah rights reserved.