Copper

Many Nickel Aluminum Bronze (NAB) alloys undergo an allotropic phase transformation, which plays an important role in determining their properties. When cooled rapidly from high temperatures, a martensitic transformation can occur, which can be detrimental to mechanical properties and corrosion resistance. Thermo-Calc can calculate the T₀ (T-Zero) temperature, which is a reasonable estimate of the martensite start temperature.

This figure shows the calculated T₀ temperature as a function of Al content for a nominal composition of UNS C95520, Cu-10Al-5Fe-5Ni (wt%).

Cu-alloys have high thermal conductivities, making them lucrative for applications such as rocket engine combustion chamber liners. NASA developed an additively manufactured version of a Cu-alloy (GRCop-42) for such applications. With our Equilibrium with Freeze-in Temperature Model, users can calculate equilibrium at the freeze-in temperature and evaluate thermophysical properties at different temperatures. This model is particularly relevant for estimating properties such as thermal or electrical conductivities. The assumption in this model is that diffusion and phase transformations are negligible when changing from the freeze-in-temperature and, therefore, that the phase amounts and compositions of phases are kept at all other temperatures. 

The figure shows the thermal conductivity (W/m.K) as a function of temperature (℃) for an additively manufactured Cu-alloy (GRCop-42). The values are compared against literature values [Chen2023] and show a good fit. This model was calculated using the TCCU6 database in Thermo-Calc.