High-temperature compression tests of Ti(C, N)–70 wt% W cermet and isothermal forging of Inconel 718 alloys using cermet molds

Abstract

In this study, TiC0·5N0.5–70 wt% W cermet specimens consisting of a core–rim grain structure with coherent interfaces and the binder phase were prepared by blending TiC0·5N0.5 and W powders with particle sizes of less than 1 μm and then spark plasma sintering the blended powders. The compression tests of the cermet specimens were conducted in the temperature range of 1873 K–2073 K in a vacuum and under Ar gas flow conditions. At all testing temperatures, this cermet exhibited much higher yield stress than MoSiBTiC and MoNbTaVW high-entropy alloys, which are some of the structural materials showing the highest strength at temperatures exceeding 1873 K. After isothermal upset forging of commercially available solid-solution heat-treated Inconel 718 alloy specimens with a diameter of 5 mm and a height of 5 mm using cermet molds at loads of 40 kN and 10 kN at 1273 K and 1373 K in a vacuum, respectively, their average grain size (2 μm) was found to be much smaller than that before forging. Such fine microstructures were assumed to be formed by dynamic recrystallization during forging.