Nanostructured Zr- and Ti-based composite materials with high strength and enhanced plasticity

Abstract

Multicomponent composite materials with the compositions Zr66Nb13Cu8Ni6.8Al6.2 and Ti66Nb13Cu8Ni6.8Al6.2 were produced by copper mold casting, and their microstructure and their room-temperature mechanical properties were investigated. The specific alloys were developed to circumvent the limited ductility of Zr- and Ti-based bulk metallic glasses by the formation of a heterogeneous microstructure consisting of a nanocrystalline matrix and ductile dendritic bcc precipitates. Comparing the microstructure of both alloys, two significant differences were observed. The volume fraction of the dendritic bcc phase is higher for the Ti-based alloy and the formed interdendritic matrix phase(s) have a different structure. The two alloys show an excellent combination of strength and plastic strain. Especially the Ti-based alloy exhibits exceptional mechanical properties, such as high fracture stress of more than 2000MPa and a plastic elongation to failure of almost 30%.