Effect of alloying elements on interdiffusion phenomena in explosive clads of 304LSS/Ti–5Ta–2Nb alloy

Dissimilar joints of 304L austenitic stainless steel (SS) and Ti–5Ta–2Nb alloy were fabricated using explosive cladding process with an aim to avoid the formation of brittle intermetallic phases at the interface. Subsequently, diffusion annealing heat treatments were carried out at temperatures in the range of 550–800 °C for various durations. In the present study, concentration and temperature dependence of the distinct diffusion zones, formed at the clad interface, due to interdiffusion of the alloying elements, have been established using Electron Probe Micro Analysis and imaging of the interface. Molar volume showed a close match with the ideal Vegard’s law at low temperatures while a non-linear negative deviation has been observed at high temperatures (800 °C) due to the formation of secondary phases such as FeTi, Fe2Ti and βTi(Fe) phases. Interdiffusion parameters evaluated by Wagner’s method showed sluggish diffusion kinetics of Fe and Ti at concentration corresponding to a two phase mixture of FeTi and Fe2Ti. Further, an attempt has been made to understand multicomponent diffusion using Dayananda’s approach and estimation of effective interdiffusion coefficients revealed ~22 µm shift of the interface from Matano plane at 800 °C.