Colossal super saturation of oxygen at the iron-aluminum interfaces fabricated using solid state welding

Solid state joining is achieved in three steps, (i) interface asperity deformation, (ii) oxide dispersion, followed by (iii) atomic contact and bonding. Atomically clean metallic surfaces without an oxide layer bond spontaneously. Despite its importance the oxide dispersion mechanism is not well studied. In this work the first ever atom probe study of iron-aluminum solid state welds show that the oxygen concentration at the interface is 20 at.%. This is significantly lower than any equilibrium oxide concentration. We therefore propose that the high-strain rate deformation at the interfaces renders the oxide unstable resulting in the observed concentration of oxygen.