Stress-driven Volta potential evolution in Ti-6Al-4 V Alloys: A multiscale bridge between crystallography and corrosion susceptibility

This study presents a multiscale approach integrating in situ Scanning Kelvin Probe Force Microscopy (SKPFM), synchrotron High-Energy X-ray Diffraction (HE-XRD), Finite Element Modeling (FEM), and Density Functional Theory (DFT) simulations to investigate the stress-driven evolution of Volta potentials in Ti-6Al-4 V (TC4) alloy. In situ SKPFM measurements show that both α and β phases exhibit a progressive reduction in Volta potential under mechanical loading, with a corresponding increase in Volta potential difference (VPD). Crystallographic strain anisotropy governs potential changes during the elastic regime, while dislocation motion dominates in the plastic regime. FEM simulations quantify stress localization, while HE-XRD provides phase-resolved strain data to calibrate FEM and DFT models. DFT simulations confirm the role of strain in the elastic stage, but highlight the shift to dislocation-driven effects in the plastic stage. This work reveals how mechanical deformation alters surface electronic structure, offering insights into localized degradation and alloy design for SCC resistance.