Spectrum of Grain Boundary Segregation Vibrational Entropy in Dilute Ni(Pd) Polycrystals

Understanding vibrational entropy of grain boundary segregation is important to understand the equilibrium state at finite temperatures. While the recent works have shown the importance of treating the grain boundary network as a collective of sites with varying atomic environments, progress in quantifying the distributions of segregation vibrational entropy is still limited to only a few systems for small coincident site lattice (CSL) boundaries. Here we apply a variant of the harmonic approximation to quantify the spectrum of vibrational entropy of grain boundary segregation in a Ni(Pd) polycrystalline system. The results show a strong correlation between 0-K segregation energy and vibrational entropy in agreement with previously reported results from small CSL boundaries using Monte Carlo simulations. The spectrum can be used with the established spectral thermodynamic framework to predict equilibrium solute content at finite temperatures, enabling a pathway to model interfacial segregation in polycrystalline materials at finite temperatures.