Cu-Zr (Copper-Zirconium)

The Cu-Zr phase diagram in [Massalski2] was updated by [2008Oka] by showing the phase diagram calculated by [2006Wan]. Four phases (Cu₂Zr, Cu₂₄Zr₁₃, Cu₅Zr₈, βCuZr₂) were added to the six intermediate phases (Cu₉Zr₂, Cu₅₁Zr₁₄, Cu₈Zr₃, Cu₁₀Zr₇, CuZr, αCuZr₂) already known in [Massalski2].

After [2006Wan], the Cu-Zr phase diagram was thermodynamically assessed by [2008Tur], [2008Yam], [2010Kan], [2010Zho], and [2011Gie]. Among these, the phase diagrams of [2010Kan] and [2011Gie] are similar. All the others are very different particularly with regard to the eutectoidal decomposition temperatures of some intermediate phase. The result of [2010Zho] is tentatively shown in Fig. 1 because some experiments have been carried out to examine the eutectoidal decomposition. Major differences between the two most recent works, [2010Zho] and [2011Gie], are: (1) Cu₅Zr in [2010Zho] is Cu₉Zr₂ in [2011Gie] and (2) Cu₅₁Zr₁₄ is stable down to 0 K in [2010Zho] whereas it decomposes eutectoidaly at 534 °C according to [2011Gie]. For the latter point, the result of [2011Gie] seems to be more reasonable because Cu₅₁Zr₁₄ with a complex crystal structure gives increasingly negative contribution to the entropy term of the Gibbs energy as the temperature increases. [2010Zho] and [2011Gie] agree that Cu₅Zr₈, which was shown in the phase diagram of [2006Wan], does not exist in the stable state.

Fig. 1

Cu-Zr phase diagram