X-ray diffraction analyses of aged U–Nb alloys

Phase transformation of metastable cubic γ-phase in U–Mo alloys

“…It has been reported that U-alloys with maximum 11 at% Mo when water quenched from ␥-phase field will transform into metastable ␣ and ␣ phases, which are slight variant of the orthorhombic lattice of ␣-U. Alloys containing 11.39-12.73 at% Mo, when water quenched will form an ordered ␥ • -phase with an ordered tetragonal structure [18][19][20][21][22]. Hence water quenched uranium alloys containing up to about 11 at% Mo are termed as "alpha phase" alloys and with more than 11 at% Mo as "gamma phase" alloys.…”

Low temperature age hardening in U–13at.% Nb: An assessment of chemical redistribution mechanisms

“…The reaction(s) corresponding to the lower C-curve [16], with a nose at 400°C, results in considerable strengthening and ductility loss [2,18,19,[21][22][23][24][25], with only marginal decrements in corrosion resistance [2]. The specific aging mechanism(s) for this low-temperature decomposition mode are unclear, though many U-Nb aging studies have proposed some variant of diffusional niobium redistribution.…”

Micro-mechanical characterisation of uranium

“…U-6Nb is metastable and hardens with age as the softer supersaturated a 00 phase decomposes to a more thermodynamically stable structure, eventually reaching a final a + c 2 equilibrium. Indentation has been used to evaluate the increases in hardness with ageing time and temperature of U-6Nb [10]. Like unalloyed uranium, U-6Nb also exhibits unusual stress-strain behaviour, which is manifested in the form of double yielding [11].…”