The Role of Composition and Phase upon the Lattice Nitrogen Reactivity of Ternary Molybdenum Nitrides

The reactivity of the lattice nitrogen in the filled β-Mn structured Co 2 Mo 3 N and the η-carbide structured Co 3 Mo 3 N and Fe 3 Mo 3 N has been investigated under 3:1 H 2 /Ar at temperatures up to 900 °C. The lattice nitrogen in Co 3 Mo 3 N was found to be reactive, as reported previously, whereas Co 2 Mo 3 N was shown to be stable up to 800 °C. Upon H 2 /Ar treatment at 900 °C, the Co 2 Mo 3 N, Co 3 Mo 3 N and Fe 3 Mo 3 N phases decomposed. These results suggest that both metal composition and phase have an influence on the bulk lattice nitrogen reactivity of the ternary nitrides.