Heterogeneous Equilibria and Phase Diagrams

Abstract

Each year the problem of reviewing in a few pages the large field of heterogeneous equilibria and phase diagrams becomes more difficult. The number of good papers in this field has increased each year as the practical value of the results has become apparent in such widely diverse fields as improvement of metals by alloying or heat treatment, substitution for criti­ cally scarce metals, ferrous and nonferrous slag metallurgy, surface finishing of metals, control of corrosion and oxidation of metals, glass making, develop­ ment of high-temperature refractories, cement technology, geologic ther­ mometry, the origin of rocks, minerals and ores, the separation and purifi­ cation of solid and liquid organic compounds, the preparation and purifica­ tion of chemicals. the utilization of natural products. the development of useful byproducts. and a host of other industrial developments. During this past year the literature has been particularly extensive because of the large number of good papers, published in Russian journals during the past few years, which have just become accessible this year by inclusion in the 1954 volume of Chemical Abstracts. More than 500 papers in the phase-equilibriu m field were noted. In this review we have tried to mention, at least by subject matter, those which contain important pertinent data. One of the best methods for presenting the results on heterogeneous systems is that proposed by Bogue & Newkirk (1) in their review of this subject two years ago in the Annual Review of Physical Chemistry. This method, based on chemical composition, divides the subject into five broad categories: (a) aqueous salt systems, (b) organic systems, (c) anhydrous salt systems, (d) metallic systems, and (e) oxides and refractory systems. Be­ cause of their long-range importance, we first of all call attention to the re­ cent advances in graphical methods, theoretical studies, new experimental techniques and apparatus, and cite reviews of certain aspects of phase equilibria. GRAPHICAL METHODS AND THEORETICAL STUDIES