Self-Propagating High-Temperature Synthesis of Carbide- and Boride-Aluminides

Abstract

TiC- and TiB2-FeAl composites have been produced using the Self-propagating High-temperature Synthesis (SHS) method under Pseudo Hot Isostatic Pressing (PHIP). When mixtures of the elemental powders were heated to a temperature near the melting point of Al under a PHIP of 150 MPa, the powder mixtures exothermically reacted and produced TiC particle dispersed and TiBB2 particle dispersed FeAl-matrix composites. As the volume factions of TiC and TiB2 particles increased from 0.3 to 0.8, the average particle size increased from approximately 1 to 10 μm and the average Vickers hardness increased from approximately 600 to 1600 in both the TiC-FeAl and TiB2-FeAl systems. The application of the PHIP remarkably reduced the porosity of the SHS products. Preheating of the elemental powder mixtures at 773 K for 30 minutes also reduced the porosity. Moreover, the preheating reduced the particle size in the SHS products. It was suggested that degassing of the powder surfaces and mutual diffusion between the different powders should have occurred during the preheating, which led to reduction in pore formation and reduction in heat generation at the SHS reactions, respectively.