Structure and mechanical properties of Ce-La alloys containing 3- 10 wt. % La

This paper describes a study of the microstructure and mechanical properties of a range of cerium-lanthanum (Ce-La) alloys with La contents of between 3 wt. % and 10 wt. %. Ce-La alloys are regarded as non-radioactive surrogates for delta-phase plutonium (δ-Pu) alloys. The Ce-La alloys were characterised using optical microscopy, energy dispersive spectroscopy and X-ray diffraction while the mechanical properties were determined using micro-hardness, ultrasonic velocity and nanoindentation measurements. The presence of La appears to impart a degree of solid solution hardening to the alloys, as indicated by the modest increase in micro-hardness with increasing La content; a small increase in elastic modulus with La content was also seen. The hardness and elastic modulus values of the Ce-La alloys in this study are similar to those of homogenized Pu-Ga alloys in the Ga-lean part of the δ-Pu phase field. Despite the propensity of the Ce-La alloys to undergo oxidation in air, the oxide thicknesses of the alloys, which were determined by energy dispersive spectroscopy, were found to be insufficient to exert a significant influence on the nanoindentation measurements.