Interdiffusion was studied in Cu-rich α-phase alloys by using couple techniques at 1023 to 1133K. The concentration profiles indicated that the diffusion distance of Mn was longer than that of Ni. The effect of the indirect fluxes became larger with increasing Mn or Ni concentration. The direct coefficients, DMnMnCu and DNiNiCu, were positive and the indirect coefficients, DMnNiCu and DNiMnCu, were negative. The 4 interdiffusion coefficients were very sensitive to the Ni and Mn concentrations. The temperature dependences of the coefficients could be described by the expressions:

DMnMnCu:      D(m2/s) = 0.00064 exp[-219(kJ/mol)/RT]

DMnNiCu:     D(m2/s) = -0.022 exp[-259(kJ/mol)/RT]

DNiMnCu:      D(m2/s) = -0.0002 exp[-218(kJ/mol)/RT]

DNiNiCu:     D(m2/s) = 0.00017 exp[-220(kJ/mol)/RT]

On the basis of the estimated values of the interaction parameters, it was concluded that the interaction energy of the Ni-Mn bonds was much larger than those of the Cu-Ni and Cu-Mn bonds.

T.Takahashi, M.Katoh, Y.Minamino, T.Yamane: Journal of the Japan Institute of Metals, 1987, 51[8], 701-9