Modification of titanium surface by its alloying with silicon using intense pulsed plasma beams

Surface alloying of Ti with Si has been performed with the use of high intensity pulsed plasma beams. In this technique, short, intense (1 μs, 3–4 J/cm2) plasma pulses serve as a source of heat to melt the near surface layer (up to 2 μm) of the Ti substrate together with a Si film (30 and 70 μg/cm2) pre-deposited on it. In the molten state, lasting a couple of microseconds, rapid diffusion of Si into Ti occurs leading to formation of new phases during rapid solidification of the molten surface layer. In the present work, an attempt has been undertaken to improve the mechanical surface properties of titanium via precipitation of hard compound particles. The main results obtained are as follows. Ti5Si3, the silicide with the highest melting point (2130 °C) of all stable phases in the Si–Ti system, is formed by the transient heat treatment. During subsequent annealing for 1 h at 800 °C a fraction (14–43%) of Ti5Si3 transforms into TiSi. The presence of silicide precipitates in the near surface layer of titanium increases dramatically its wear resistance.