Electric current is typically associated with electromigration damage, but under steady current-carrying conditions it can also bias lattice stability. Here, in situ synchrotron X-ray diffraction and nanodiffraction show that a current density of \(1.5\times {10}^{3}\)A cm−2 retains hexagonal η-Cu6Sn5 under conditions where temperature-matched thermal treatment drives the η → η′ transformation. The retained η phase accommodates the current through anisotropic elastic distortion, with c-axis expansion of ~1.3% and basal-plane contraction of ~0.8%, accompanied by plane-selective dislocation rearrangement and partial lattice recovery after current removal. Grain-resolved stress/strain mapping yields a spatially averaged post-ECS principal-stress scale of ~30–40 MPa, consistent with an order-of-magnitude electron-wind estimate, while the associated elastic-energy density of 9–12 MJ m−3 remains well below the reconstructive barrier of ~150 MJ m−3. These results identify a phenomenological electron-wind-driven elastic accommodation regime in η-Cu6Sn5 under the present current density and experimental geometry, accompanied by plane-selective defect rearrangement, and are experimentally consistent with a Gibbs-like \(T-\sigma -J\) description of the current-carrying steady state.
