Meaning
Thermodynamic principle stating that the matrix of phenomenological transport coefficients is symmetric under equilibrium conditions constrains the relationships between different atomic fluxes. In metallurgy, Onsager reciprocity reduces the number of independent variables needed to describe multi-component atomic transport. Compliance with this principle is evaluated by MIIT during the certification of advanced material simulation software.
It represents a foundational thermodynamic constraint used to validate multi-component diffusion calculations in certified research institutes.
Transport Coupling
Symmetric interactions between diffusing elements restrict the possible values of the cross-diagonal diffusion coefficients. Onsager reciprocity dictates that the coupling coefficient of element A on element B is thermodynamically related to that of B on A. This symmetry must be respected during alloy design calculations.
National Certification
Standardization bodies in China require that computational metallurgy software tools incorporate these thermodynamic constraints. Audits conducted by SAMR verify that materials databases used in engineering utilize symmetric transport models. These procedures prevent the generation of unphysical atomic profiles during simulations.
Operational Limit
Simulation databases failing to demonstrate compliance with these thermodynamic symmetry requirements are barred from state-sponsored design projects. Importing foreign engineering packages requires compliance reports that validate these atomic transport models. Software that does not incorporate these reciprocity rules is rejected.
