Reasons For The Errors In The Graphics Of Salt System

Abstract:

Often the errors in graphics of T-x-y-z diagrams for the quaternary salt systems and their sections are associated with the incorrect understanding of phase diagram structure. For example, at the consideration of eutectic type system LiF-LiCl-LiVO3-Li2CrO4 we have revealed that the intersection lines of two ruled hyper-surfaces on one of the two-dimensional section are missed. Such diagrams have two types of ruled hyper-surfaces sets: 1) with one-dimensional forming simplex and two directing surfaces; 2) with two-dimensional forming simplex and three directing lines. One directing line of first type ruled hyper-surface is degenerated on the hyperprism edge in the case of system without solid-phase solubility. In the same case, a ruled hyper-surface of the second type has two degenerated directing lines, which are projecting into tetrahedron tops. So the section view can be suggested from the section arrangement relative to the diagram elements in the tetrahedron. The errors in graphics of diagrams with the anomalous structure of solid-phase solubility are met too. For example, two-phase region RbJ+NaF was depicted as the homogeneous region of solid solution a on the base of RbJ on the vertical section NaJ-(0,5RbJ+0,5NaF) in the eutectic subsystem NaJ-RbJ-NaF of ternary reciprocal system Na,Rb//J,F. Analogous mistake takes place nearby the component NaJ: two-phase region NaJ+NaF was indentified as the homogeneous region of solid solution b on the base of NaJ. Furthermore the boundary of regions L+a and L+a+NaF has incorrect view as horizontal line. As the solid-phase solutions a and b have anomalous form on the horizontal sections of T-x- diagrams, they can be described as the triangular ones, in accordance with the point-type, linear and planar phases.

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