Phase transformations and some laws obeyed by nonvariant reactions in binary plutonium systems

Fifty-three eutectoid reactions detected in thirty of the virtually all known binary phase diagrams of plutonium are analyzed. It is shown that they obey a universal empirical dependence relating the parameters of nonvariant (eutectoid and peritectoid) transformations and the temperatures of phase formation. Cases of deviation from this dependence are described, which require amendment of the phase diagrams (of Pu with Cm, Hf, and Al). The dependence is used for analyzing the parameters of eutectoid decomposition of the d-solid solution of Pu in plutonium alloys with elements of the d-solid group at atmospheric and enhanced pressure and variants of nonvariant reactions in the Pu-Al (d-phase and Pu3Al and PuAl compounds) and Pu-Np (four eutectoid and four peritectoid transformations) systems. It is shown that the dependence can be used for amending and predicting the parameters of nonvariant reactions in the Pu-Np system.