Effects of Dendrite Size on Tensile Deformation Behavior in Zr-Based Amorphous Matrix Composites Containing Ductile Dendrites

Abstract

Four Zr-based amorphous matrix composites whose dendrite size was varied with plate thickness were investigated, and the deformation mechanisms related with improvement of strength and ductility were investigated by focusing on how the size of ductile beta dendrites affected the initiation and propagation of deformation bands. These composites contained 47 to 49 vol pct of dendrites sized by 14.7 to 42.8 mu m, and they showed excellent tensile properties of yield strength of 1.3 to 1.5 GPa and uniform elongation up to 11.7 pct. According to the observation of tensile deformation behavior of the composite with a plate thickness of 5 mm, many deformation bands were formed inside dendrites in several directions, and the deformation bands met crossly each other to form widely deformed areas. Because the wide and homogeneous deformation in this composite beneficially worked for the tensile strength and ductility simultaneously, the optimum size of dendrites and thickness of plates were approximately 19 mu m and 5 mm, respectively. Considering that Zr-based amorphous matrix composites are mostly used in a plate form in their conventional applications, the current research can provide the optimum plate thickness data for their fabrication processes such as rolling, extrusion, and strip casting.