Enhancement of ductility and plasticity of Zr55Cu30Al10Ni5 bulk glassy alloy by cold rolling

With the aim of improving ductility and plasticity of a Zr55Cu30Al10Ni5 bul k glassy alloy, a cold rolling treatment leading to the rolled structure wi th high-density slip bands was performed. A number of slip bands were intro duced along the maximum shear stress plane by cold rolling, and the first s lip bands were found to slant significantly with increasing reduction ratio in thickness. At the critical reduction ratios, the second slip bands were introduced at a reduction ratio of 30%, followed by the third slip bands a t a reduction ratio of 60%. Mechanical properties of the rolled samples wer e examined by bending test and Charpy impact test. The maximum bend deflect ion value before failure increased with an increase of reduction ratio, ind icating that the cold rolling improves the plasticity of the bulk glassy al loy. Since the Charpy impact value depends on the rolling direction, we sel ected an optimum rolling direction in which the maximum Charpy impact value is obtained. The control of the rolling direction causes an increase in th e Charpy impact value by 36% as compared with the unrolled alloy. Consequen tly, the cold rolling process is concluded to be a valuable method for impr oving the ductility and plasticity of the bulk glassy alloy.