Investigation on NiAl-TiC-Al2O3 composite prepared by self-propagation high temperature synthesis with hot extrusion

The NiAl-TiC-Al2O3 in situ composite was fabricated by self-propagation high temperature synthesis and hot extrusion (SHS/HE) technique using element powders. Its microstructure and mechanical properties were investigated by OM, SEM, TEM and compression test. The results revealed that the NiAl-TiC-Al2O3 composite was densified by the SHS/HE process and had fine microstructure. In the composite, TiC particles along NiAl grain boundary agglomerated and grew, but the TiC particles in NiAl grain were fine. The TiC and Al2O3 particles exhibited an obvious trend to distribute along extrusion direction. Moreover, stacking fault and microtwins in TiC particles and thin amorphous layer along NiAl/TiC phase interface were also observed. In addition, Ti2AlC particle with intergrowth TiC plate inside formed along the NiAl grain boundary. Generally the SHS/HE synthesized NiAl-TiC-Al2O3 composite possessed better mechanical properties, especially at room temperature, which should be ascribed to the fine microstructure and predeformation caused by hot extrusion. (c) 2012 Elsevier Ltd. All rights reserved.