Effect of Pd, temperature and time on wetting and interfacial microstructure of bulk metallic glasses TiCuZrPd on Ti-6Al-4V substrate

Abstract

Melting behavior of TiCuZrPd bulk metallic glasses (BMGs) containing 10, 14, 20 at.% Pd was studied by DSC and their melting range is: 845–910, 831–900, 874–911 °C, respectively. Wetting of TiCuZrPd BMGs on Ti-6Al-4V substrate was studied at 850, 880 °C for 5, 10, 30 min. It was found that wetting angle decreases and spreading area increases with increasing temperature and time. Interfacial microstructure of TiCuZrPd/Ti-6Al-4V solidified couples was studied with scanning electron microscopy and energy dispersive spectroscopy. Three intermediate layers were identified at the interface between Ti-6Al-4V substrate and TiCuZrPd BMGs. The first layer adjacent to substrate is composed mostly of Ti, with concentrations of Al lower and V close to that in Ti-6Al-4V, whereas Cu, Pd and traces of Zr are also present. This indicates that this layer was formed by diffusion of Cu, Pd and Zr into substrate. Second layer, adjacent to the first, has higher concentration of Cu compared to the first, there is no V in this layer and concentration of Al is about 50% lower than that in the first. This and the fact that there is no Al in third layer, adjacent to BMG, indicates that Al and V do not diffuse into BMG. In the third layer concentration of Ti is similar to that in the second layer but still 50% higher than in TiCuZrPd, while concentrations of Cu and Zr are lower and concentration of Pd close to that in TiCuZrPd.