Mechanical behavior of δ-phase Pu–Ga alloys. Part I: Constitutive model

We developed a constitutive model, based on the mechanical threshold strength (MTS) model reported by Follansbee and Kocks [P.S. Follansbee, U.F. Kocks, Acta Metall. 36 (1988) 81], to predict the stress/strain behavior of face-centered cubic (fcc) δ-stabilized plutonium–gallium (Pu–Ga) alloys. Input to the model is derived from our previous work on other fcc metals and published test data for Pu–Ga alloys. The model accounts for the effects of temperature, strain rate, grain size, and alloy content on the constitutive behavior. In Part I, we describe the development of the model and present all the pertinent equations and parameters. In Part II, we validate the model against existing literature data and demonstrate how the model is used to quantify the effects of test condition, grain size, alloy content, and impurity levels.