Abstract: The solid powder boronizing， on the surface of titanium alloys with matrix structure αTi of TA1 and(α+β)Ti of TC4， was investigated. The morphology of boride layer was observed by polarizing microscope and scanning electron microscope(SEM). The phase composition of boride layer was analyzed by Xray diffraction(XRD). The results show that when boronizing temperature is in the range of 850~1000℃， diffusion layers on TA1 in a multilayer structure are paralleled to the surface of the substrate， which composes of Ti3O and TiB phases. When the temperature is higher than 920℃， TiB becomes the major component in the diffusion layer with TiB2， and the content of titanium borides increases with temperature. When the temperature is lower than 1000℃， Ti3O and TiB are the major components of the layer on TC4. When it is higher than 1000℃， the layer is TiB2 and TiB whisker. Boronizing temperature above 1000℃ is the sufficient condition for the formation of titanium borides.

Key words: pure titanium TA1, titanium alloy TC4, titanium boride, solid boronizing, diffusion kinetics