An attempt to estimate the extent of the single phase region of the ZrMn 2 phase by means of the X-ray diffraction-profile halfwidths

Abstract

A new method for determining the extent of single phase regions has been proposed. The chemcial composition dependence of the powder X-ray diffraction (XRD)-profile halfwidths has been used for an estimation of the extent of the single phase region of the ZrMn 2 phase in the ZrMn binary alloy system. The result obtained by this method has been compared with those provided by other known methods such as the standard powder XRD-pattern analysis, the chemical composition dependence analysis of the lattice parameters, the P-C-isotherm measurement and microstructure examination. This “halfwidth” method is a fully sensitive one by means of which the extent of the single phase region can be determined. The region extends approximately from ZrMn 1.9 to ZrMn 2.9, although the lower limit varies from ZrMn 1.9 to ZrMn 2.0 depending on the applied methods. The region obtained by this work is narrower than that indicated in the latest ZrMn binary phase diagram. Furthermore, an unidentified phase has been observed in the hyper-Zr alloys, besides the ZrMn 2 and α-Zr phases. That phase is likely to be the ZrMn structure, which is perhaps stable at a high temperature and unstable at room temperature.