Investigation of the NpZr and UZrNp systems

Thermodynamic study of the Np–Zr system

“…Additionally, DTA experiments [7] discussed in Section 2.1, showed that no well-defined peaks were observed above 913 K. It has been pointed out in Ref. [43] that it is highly probable that the melting points of (c-Np, b-Zr) measured by Rodríguez et al [11], actually correspond to the liquid + b-Zr liquidus in the nonideal phase diagram. This comparison is found to be consistent with our phase diagram and is shown in Fig.…”

“…Fig. 2 compares the phase diagram (Model 1) with dilatometry and EPMA performed by Rodríguez et al [11].…”

“…[6,7,9], the decomposition of this phase into a mixture of c-Np and a-Zr is assumed to take place at about 823 K. The only experimentally validated data on the composition range is mentioned in Ref. [11], where it has been found that this phase extends from 65.3 to 78.2 at.% Zr.…”

“…Another group of experimentalists, Rodríguez et al [11], performed dilatometry on three alloys of compositions 40, 72, and 91 at.% Zr. EPMA and microscopic examination of these samples showed complete mutual solubility between the c-Np and b-Zr phases up to their respective melting points.…”

“…It was also found that due to the low solubility of Zr in Np, there were only small changes in the melting points and transition temperatures of Np-Zr alloys. On the contrary, Rodríguez et al [11] proposed a tentative phase diagram based on dilatometry, electron probe micro analysis (EPMA) and micrographic studies, that showed the Np-Zr system to be completely ideal. These experimental works are discussed in detail in Section 2.1.…”