Robert M. Aikin

Heavy fermion behavior in CePtSi and CeRuSi

We present results of specific heat, electrical resistance, and magnetic susceptibility measurements on the heavy fermion system CePtSi and compare it to CeRuSi. Both compounds show a low‐temperature maximum in cp/T, usually associated with the formation of a coherent heavy fermion ground state. An additional feature in cp/T is observed for CePtSi and is attributed to cooperative magnetism, an interpretation confirmed by magnetic measurements. A comparison with other heavy fermion systems, especially stoichiometric and nonstoichiometric CeCu2Si2, is performed.

Magnetic anisotropy in the UxTh1−xZn8.5 system

We have investigated the source of the anisotropic susceptibility of UZn8.5 by preparing single crystals of UxTh1–xZn8.5 for small x. Preliminary indications are that anisotropic exchange, rather than crystal field effects, are responsible for the anisotropy, but possible impurity contributions to the (anisotropic) susceptibility of the ThZn8.5 do not permit a stronger statement. Further measurements for small x show that both the electronic specific heat and the susceptibility at low temperature are strongly enhanced, and that Kondo‐type resistivity minima are observed. The enhancements are somewhat reduced in the concentrated system UZn8.5.

Unraveling the Age Hardening Response in U-Nb Alloys

Complicating factors that have stymied understanding of uranium-niobium’s aging response are briefly reviewed, including (1) niobium inhomogeneity, (2) machining damage effects on tensile properties, (3) early-time transients of ductility increase, and (4) the variety of phase transformations. A simple Logistic-Arrhenius model was applied to predict yield and ultimate tensile strengths and tensile elongation of U-4Nb as a function of thermal age. Fits to each model yielded an apparent activation energy that was compared with phase transformation mechanisms.

Update on LANL DU U-10Mo Casting and on Characterization of Y-12 LEU Casting

This report presents an overview of LANL casting procedure and characterization of recent DU U-10 Mo castings and characterizes recent LEU U-10Mo casting from Y-12.