Correlation of microstructure and tensile properties of Ti-based amorphous matrix composites modified from conventional titanium alloys

In this study, three Ti-based amorphous matrix composites containing ductile dendrites were fabricated by adding alloying elements of Zr, Ni, and Be in conventional titanium alloys such as the Ti-6Al-4V alloy in order to develop new cost-effective Ti-based amorphous matrix composites having improved tensile ductility. Deformation mechanisms related with improvement of strength and ductility were investigated by focusing on how ductile dendrites affected the initiation and propagation of deformation bands or shear bands. The composites contained similar to 61-76 vol% of large dendrites sized similar to 37-81 mu m, and had excellent tensile properties of yield strength over 1 GPa and elongation over 5%. In the composite containing increased amounts of V and Al, which were effectively working to control dendritic beta phases, many deformation bands were formed inside dendrites in directions different from previously formed deformation band directions because the dendrites were relatively small. As the deformation proceeded further, deformation bands crossed each other, and the deformation occurred homogeneously in wide areas, while multiple shear bands were well developed in the amorphous matrix. This wide and homogeneous deformation in both dendrites and amorphous matrix beneficially worked for the tensile ductility, thereby showing high strength and elongation simultaneously. (C) 2012 Elsevier B.V. All rights reserved.