Deposition Temperature Induced Texture and Strengthening of Ti/Ni Multilayer Thin Films

Strong thermal effect on microstructure and mechanical properties of Ti/Ni multilayer thin films was observed from in-situ heating during deposition and subsequent annealing. Films deposited at low-temperature show preferred crystallographic texture for both Ti and Ni layers, with columnar structure extending through the layers. The columnar structure become more distinct and complete with the increase of temperature up to 300°C, and meanwhile more atomic diffusion and intermixing occur along the Ti/Ni interfaces, promoting the formation of Ti-Ni intermetallic precipitates. High-temperature deposition causes disintegration of the layered structure. Columnar Ti-Ni alloys and further recrystallized alloys were detected with preferred crystallographic texture. For material strength, an increased hardness trend is observed with increasing deposition temperature even with much larger grain size compared to room temperature case. Furthermore, for multilayer system deposited under low temperature, post annealing results in higher hardness with minimal microstructure modification, with more strengthening observed in lower deposition temperature case.