The Material to Material Calculator is a module included in all Thermo-Calc installations that allows you to examine how materials transition from one into the other. These calculations are only based on thermodynamic equilibrium and are thus much faster and easier than involving diffusion calculations. The Material to Material Calculator is included in all Thermo-Calc installations.
The example plot shows the gradual transition from a martensitic stainless steel on the left to Alloy 800 on the right at 650 °C. Neither material is expected to form any detrimental phase on its own at this temperature. We see, however, that within the transition zone of these two materials, the detrimental sigma phase can potentially occur (red line). This type of calculation is simple and fast, but neglects any non-linear diffusion effects. Consequently, the actual phases being present in a welding joint or diffusion couple of these two materials might differ.