Mechanical properties of nanostructured TiN-AlN composites rapidly consolidated by pulsed current activated sintering

Commercial TiN and AlN powders were high-energy ball milled for various durations and consolidated without a binder using the pulsed current activated sintering method (PCAS). The effects of milling on the sintering behavior, crystallite size and mechanical properties of the TiN-AlN composites were evaluated. A dense nanostructured TiN-AlN composite with a relative density of up to 99% could be readily obtained within 3 min. The ball milling effectively refined the crystallite structure of the TiN and AlN powders and facilitated subsequent densification. The sintering-onset temperature was appreciably reduced by milling for 40 h from 1200 C to 1000C. Accordingly, the relative density of the TiN-AlN composite increased as the milling time was increased. This clearly demonstrates that the quick densification of nanostructured TiN-AlN bulk materials to near the theoretical density could be obtained by the combination of PCAS and the preparatory high-energy ball milling process.