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While numerous studies have investigated the low-strain-rate constitutive response of beryllium, the combined influence of high strain rate and temperature on the mechanical behavior and microstructure of beryllium has received limited attention over the last 40 years. In the current work, high strain rate tests were conducted using both explosive drive and a gas gun to accelerate the material. Prior studies have focused on tensile loading behavior, or limited conditions of dynamic strain rate and/or temperature. Two constitutive strength (plasticity) models, the Preston-Tonks-Wallace (PTW) and Mechanical Threshold Stress (MTS) models, were calibrated using common quasi-static and Hopkinson bar data. However, simulations with the two models give noticeably different results when compared with the measured experimental wave profiles. The experimental results indicate that, even if fractured by the initial shock loading, the Be remains sufficiently intact to support a shear stress following partial release and subsequent shock re-loading. Additional “arrested” drive shots were designed and tested to minimize the reflected tensile pulse in the sample. These tests were done to both validate the model and to put large shock induced compressive loads into the beryllium sample.

Abstract: UPt3 exhibits anomalous, possibly time-fluctuating antiferromagnetic (AFM) order below 6K. Th substitution induces conventional AFM order with the same magnetic structure. Recent μSR studies on U1− x Th x Pt3 for showed that the transition into the conventional AFM state was sharp for , but broadened for (Phys. Rev. B 84 (2003) 224421), indicative of a crossover behavior. We present X-ray diffraction and transmission electron microscopy (TEM) results that show no significant material inhomogeneity in those samples. However, specific heat measurements corroborate the μSR measurements and show signs of an increase near 7K for . This supports the conjecture that Th impurities slow down the fluctuating AFM, rendering them observable on the timescale of thermodynamic measurements. [Copyright &y& Elsevier]