Processing and mechanical properties of materials in the Hf–N system

Samples of hexagonal α-Hf containing up to 30 at.% N in solid solution were made by a solid-state reaction. The brittle-to-ductile transition temperature increased as the %N increased. Steady-state compressive deformation has been measured from 20 to 1000 °C. The data for pure Hf could be fit using a threshold stress with a stress exponent of 5. The stress exponent of the Hf–N solid solution materials was between 5 and 8. The experiments could be interpreted on the basis of dislocation-controlled plasticity, with N acting as classical solid-solution hardening solutes. Transmission electron microscopy supported this interpretation.