Mechanical behavior of δ-phase Pu-Ga alloys. Part II: Model verification and application

We validated the mechanical threshold strength (MTS) model, developed in Part I, with approximately 50 different experimental results from the literature for both yield strength and ultimate tensile strength on Pu-Ga alloys. One standard deviation of the differences between the model’s yield-strength predictions and the experiments was 7.5% of the measured yield strength. The model also worked well predicting the ultimate tensile strength (UTS) of the alloys with gallium concentrations of 1 wt% or greater, although the accuracy of the UTS predictions was not as good as for yield strength. After validating the model, we studied the effects of gallium concentration, grain size, iron and nickel content, and carbon concentration on the yield strength of Pu-Ga alloys. The gallium concentration affected the yield strength more than any other microstructural variable. The yield strength increased 50% between 1 at.% Ga and 5.4 at.% Ga alloying addition. The grain size also produced a measurable strengthening effect, typical of other face-centered cubic metals. The yield strength increased 15% with a reduction in grain size from 50 μm to 10 μm. Finally, we found that there were no observable yield-strength effects resulting from different amounts of iron, nickel, or carbon impurities.