Thermal conductivity of uranium: effects of purity and microstructure

Thermal conductivity curves for polycrystalline uranium are presented for the temperature range below 373$sup 0$K. The curves are for specimens prepared by different fabrication procedures from material of known purity and hardness. Included is a curve for U/2wt percent Mo alloy. Different mechanisms appear to be influencing the thermal conductivity behavior of uranium in well- defined temperature regions: below 37 to 43$sup 0$K, approximately 40 to approximately 80$sup 0$K, 80 to approximately 280$sup 0$K, and from 280$sup 0$K to the $alpha$ $Yields$ $beta$ transformation temperature. Mechanisms responsible for results in one temperature region continue to exert a strong influence in the next higher temperature region. Impurities and initial microstructure seem to influence results at any starting temperature. Evidence is presented for the possibility of imperfection ordering in uranium between approximately 40 and approximately 280$sup 0$K. It is postulated that the type of ordering is capable with a martensite-like behavior and that all physical property results depend on the extent of a modification of the $alpha$-phase on cooling below approximately 280$sup 0$K. (auth