Brittle–ductile transitions in vanadium and iron–chromium

We report ongoing experimental work on fracture and brittle–ductile transitions in vanadium, iron and iron–9% chromium single crystals and polycrystals. Tests were carried out by four-point bending of pre-cracked specimens in the temperature range 77–300 K, at a variety of strain rates. For a given material, variation of the brittle–ductile transition temperature with strain rate allows us to estimate an activation energy for the controlling process; for vanadium this was found to be ∼0.37 eV, for iron ∼0.21 eV and for iron–9% chromium ∼0.11 eV.