Nanocrystalline matrix TiC-Al3Ti and TiC-Al3Ti-Al composites produced by reactive hot-pressing of milled powders

摘要

Mechanically alloyed nanocrystalline TiC powder was short-term milled with 40 vol.% of Al powder. The powders mixture was consolidated at 1200 °C under the pressure of 4.8 GPa for 15 s and at 1000 °C under the pressure of 7.7 GPa for 180 s. The bulk materials were characterised by X-ray diffraction, light and scanning electron microscopy, energy dispersive spectroscopy, hardness, density and open porosity measurements. During the consolidation a reaction between TiC and Al occurred, yielding an Al3Ti interme-tallic. The microstructure of the produced composites consists of TiC areas surrounded by lamellae-like regions of Al3Ti intermetallic (after consolidation at 1200 °C) or Al3Ti and Al (after consolidation at 1000 °C). The mean crystallite size of TiC is 38 nm. The hardness of the TiC-Al3Ti and TiC-Al3Ti-Al composites is 13.28 GPa (1354 HV1) and 10.22 GPa (1041 HV1) respectively. The produced composites possess relatively high hardness and low density. The results obtained confirmed satisfactory quality of the consolidation with keeping a nanocrystalline structure of TiC.