Before Surfacing: Microstructure consists of equiaxed
grains of copper solid solution.
After Surfacing: Microstructure consists of very
elongated grains of copper solid solution; this is due to
heavy compressive load & hot forging action on the
material. During friction stir surfacing a large amount of
heat is generated due to friction, this results in substantial
heating at the contact region between the tool and
material. Due to recrystallization during friction stir
surfacing the friction stir surfaced material exhibits very
elongated grains of copper. No distorted grains were
observed in the friction stir surfaced region of the
material.