Specific heat capacity of the intermetallics ε-Cu3Sn, η/η′-Cu6Sn5, Al3Ni and Al3Ni2

Including state-of-the-art physical understanding of thermal vacancies in Calphad models

“…In Calphad assessments, a constant value of the stable solid heat capacity description is usually adopted after T melt 10 . This avoids artificial re-stabilization of solid phases at very high temperatures due to too large heat capacities above the melting point 24,25,45 . Additionally, it is common in Calphad assessments to linearly interpolate heat capacity of multicomponent phases between the elements ("Neumann-Kopp rule").…”

“…Additionally, it is common in Calphad assessments to linearly interpolate heat capacity of multicomponent phases between the elements ("Neumann-Kopp rule"). This usually causes unrealistic heat capacity peaks for multicomponent phases at the melting points of the constituting elements 24,46 . To avoid the fingerprint from the elemental melting points in alloys' heat capacities we extend the linear extrapolation of elemental heat capacity beyond the melting point, however -to avoid re-stabilization at very high temperatures-only up to 2 * T melt , above which a constant value is adopted.…”

“…Additionally, The Calphad method's main principle is modelling "from bottom to top" 10 , which means that a reliable extrapolation to any multicomponent system will not only depend on the unary system descriptions and how compatible they are at higher temperatures, but also on the extrapolation method, which is usually the Neumann-Kopp rule 23 . While this method has proven effective in several cases, sometimes it can yield inconsistent results and be even misleading [23][24][25] .…”