Epitaxial interface of nanocrystalline TiC formed between Cu-10Sn-15Ti alloy and diamond

Abstract

A TiC layer of columnar grains heteroepitaxially grew in the same crystallographic orientation on diamond (100) and (110), without any transitional phase intervening between the diamond crystal and the TiC layer, when diamond grits reacted with a Cu-10Sn-15Ti alloy at 925 °C for 5 min, in a vacuum environment. The thickness of the TiC layer was in the range of 500–600 nm. The concentration of carbon in the TiC layer was not uniform. The concentration of carbon decreased with increase in distance from the diamond–TiC interface. Anisotropy in the lattice constant of TiC was significant near the diamond–TiC interface, wherein the lattice constant in the orientation parallel to the diamond [100] was larger than those perpendicular to the diamond [100], for the TiC layer grown on the diamond (100) plane. For a TiC layer which grew on the diamond (110) plane, columnar TiC grains with lateral dimensions ranging from 40 to 60 nm developed in a spiral pattern along the [110] axis. The interfacial stress arising from the lattice mismatch between TiC and diamond was relieved partially by aligning the lattice of TiC and diamond in a ‘five-to-six’ registry, and further by forming abundant grain boundaries in the TiC layer.