Determination of the phase composition of alloys by the improved Hillert method

Abstract

The Hillert method of computing activities of components along tie-lines in two-phase regions in ternary phase diagrams’ isothermal sections has been enlarged to such regions, which do not contact the corresponding binary diagrams. This became possible by using the modified Hillert equation in which the change of the activity of a given element is a function of the slope of the corresponding tieline only. As an example, it has been shown how such computations could be performed using an isothermal section of a Fe-C-X phase diagram where X is a carbideforming element and which contains several tie-line triangles