Pseudomorphic growth of iron on hot copper

An iron deposit in which there was a thickness gradient was grown in ultra-high vacuum (< 10−7 torr) on a hot (400°C) copper surface prepared inside the vacuum chamber. Electron micrographs of the iron-copper bicrystal revealed that the growth of iron began with the generation of three-dimensional iron nuclei. These nuclei were f.c.c. and their lattices were strained to give a coherent copper-iron interface. The nuclei grew in size as the thickness of the iron increased and dislocations to accommodate part of the misfit between γ-iron and copper were generated. The dislocations were in mixed orientation and had Burgers vectors which were inclined to the iron-copper interface. A further increase in deposit thickness was accompanied by the nucleation of b.c.c. (α) iron.