Fast phase mapping of mechanically alloyed Cu–Zr by using nanoindentation

Abstract

Identification of possible amorphous phases of micron or submicron size in metallic alloys usually relies on transmission electron microscopy, which often faces great challenge in sample preparation. In this study, nanoindentation was introduced as an efficient approach to map possible amorphous phases in a Cu–Zr system processed by accumulative roll bonding. This was achieved by taking the advantage that the amorphous phases of CuZr are associated with characteristic “pop-in” events in the nanoindentation load-displacement curves, which are absent for crystalline CuZr phases of similar composition. By combining nanoindenation with scanning electron microscopy, it was found that significant mechanical alloying has occurred in Cu–Zr during accumulative roll bonding, which resulted in regions of ultra-fined composite of both crystalline and amorphous CuZr phases. Such structure was consistent with that found by high-resolution transmission electron microscopy. It thus suggests that nanoindentation offers an alternative method for preliminary but effective mapping of possible amorphous phases in metallic alloy system over a relatively large scale than transmission electron microscopy.