The intermetallic alloy FeAl, which exhibits extraordinary oxidation and sulfidation resistance, was shown to be thermodynamically compatible with WC. Thermodynamic calculations showed that the solubility of WC in liquid Fe-40 at. % Al at 1450°C is approximately 2 at. %. Since, in addition, liquid iron aluminide wets WC very well, the WC/FeAl system lends itself to liquid-phase sintering resulting in close-to-theoretical densities. Using simple processing techniques, almost fully dense cermets containing nominally 20.6 wt% FeAl binder were produced. With a novel one-step infiltration technique, 98% dense cermets with only 7 wt% FeAl binder were fabricated. Room temperature bend strengths and fracture toughnesses for WC-20.6 wt% FeAl reached values of 1680 MPa and 22 MPa·m~(1/2), respectively. Consistent with the high fracture toughnesses, ductile binder fracture was observed on the fracture surfaces. However, even in the specimens with the best mechanical properties, pores containing oxide inclusions were found. This suggests that future improvements in processing are likely to further improve the mechanical properties of these materials. Insufficient process control may also be the reason why WC/FeAlNi cermets did not show improved mechanical properties, although Ni strengthens FeAl considerably. For WC bonded with binary iron aluminide, mechanical properties were not only measured at room temperature, but also at 800°C. As expected, the bend strengths of WC/FeAl at 800°C in air increased with increasing WC volume fraction, and the fracture toughnesses were significantly higher than at room temperature.
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