| This paper was focused to investigate the effect of extrusion and heating rate on the reactive synthesis and the microstructure of products formed by reactive synthesis. The mixing of elemental powders was carried out by V-blender. The mixed powders were canned, sealed under vacuum, and were hot extruded at 450℃ under extrusion ratio 20 : 1. For powder extruded and cold compacted specimens, thermal analysis have been performed. In the effect of extrusion, the ignition temperature(T₁) of extruded specimens was found to be lower than that of cold compacted specimens. This may be due to breakdown of aluminium oxide films and elongation of mixed powders by hot plastic-deformation. In the effect of heating rate, both ignition temperature(T₁) and combustion temperature(T_c) was found to be increased with increasing heating rate. In particular, the ignition temperature of extruded specimens was below the melting temperature of aluminium under the heating rate of 40℃/min. Also, phase of reaction products depended upon combustion temperature. Microstructure of reaction products consists of unreacted titanium, TiAl and Ti₃Al. However, unreacted titanium was not observed after heat treatment. |
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