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What's in a Name



Ursula R. Kattner


In the early days of alloy phase diagrams phases were named using Greek letters in unary systems, from lower temperatures to higher temperatures, and in binary systems from the left to the right hand side of the system. This convenient convention allows for easy nomenclature in a specific alloy familiy. However, with only 24 letters in the Greek alphabet it was only a matter of time before problems would arrise from this naming convention, especially for ternary or higher-component systems. For example, τ is frequently used for a ternary phase and if more than one ternary phase occurs in a system then the ternary phases are numbered, i.e., τ1, τ2, etc. Since many commercial alloys consist of a number of ternary systems, it is forseeable that this practice may result in a Tower of Babel of phase names. This is even true for the Greek phase names used for the unaries and binaries.
Journal of Phase Equilibria and Diffusion


CALPHAD, phase name, crystallography, Materials Genome Initiative


Kattner, U. (2013), What's in a Name, Journal of Phase Equilibria and Diffusion, [online], (Accessed April 24, 2024)
Created November 4, 2013, Updated November 10, 2018