High-performance C+ + implementation of the Self-Association Model for Cu–Zn alloy thermodynamics

This work presents a C+ + implementation of the Self-Association Model (SAM) for rapid thermodynamic analysis of Cu–Zn binary liquid alloys. The model calculates Gibbs free energy of mixing, component activities, concentration fluctuations, and short-range order directly from statistical-mechanical principles with minimal parameterisation. Results at 750 K show strong agreement with CALPHAD reference data, reproducing the positive deviations from ideal solution behaviour and confirming segregation tendencies driven by homo-atomic clustering. Microscopic descriptors ( S cc ( 0 ) > S cc id , α 1 > 0 ) reveal short-range order consistent with neutron-diffraction observations. The C+ + framework featuring modular, object-oriented classes achieves sub-second computation per composition sweep, offering high numerical stability and scalability for multicomponent alloy systems. The open-source implementation (Zenodo DOI: 10.5281/zenodo.17576203) enhances reproducibility and integration into digital-twin and materials-informatics workflows. This work demonstrates an efficient, extensible tool for computational alloy design and thermodynamic screening.