Studies of the interfacial structure of a linear friction welded Fe/Ni joint: First principles calculation and TEM validation

In this work, the interfacial structure of a linear friction welded (LFWed) Fe/Ni joint was studied using CASTEP based on first principles. Calculations clearly show that the Fe(100)/Ni(100) structure is the most stable bonding structure at the Fe/Ni interface, where 3d orbital electrons have a significant contribution to the interface bond and the Fe(3d)-Ni(3d) bond displays a strong covalent bonding effect. Transmission electron microscopy and energy-dispersive X-ray spectroscopy were used to evaluate the LFWed Fe/Ni interface. The experimental results show that the stable bonding structure appears at the weld edge and the orientation is (100)Fe//(100)Ni, [010]Fe//[011]Ni, as predicted by calculations. While at the weld center orientation is (011)Fe//(101-)Ni, [100]Fe//[112-]Ni due to lattice distortion.