“…The lattice parameter of Cu remains nearly unchanged before milling for 6 h, and increases sharply after milled for 6 h and then reaches its ultimate value. The increase of the lattice parameter of Cu indicates the formation of Cu(C) solid solution [11][12][13]15 . Thus, after milled for 6 h, the concentration of carbon in Cu increases with the increase of milling time, and reaches its saturation milled for 24 h.…”