Regensburg 2004 – wissenschaftliches Programm
M 10.6: Vortrag
Montag, 8. März 2004, 17:45–18:00, H4
Ni and Mn self-diffusion in Ni-Mn alloys — •Serguei Peteline and Helmut Mehrer — Institut für Materialphysik, Universität Münster, D-48149, Münster, Germany
Ni and Mn self-diffusion has been investigated in Ni50Mn50 alloys over wide temperature ranges. The alloys were prepared by the group of Prof. Chang at the University of Wisconsin, USA. The diffusion of 63Ni and 54Mn was measured by the radiotracer method in disordered fcc, B2 and L1(0) structure regions present in this compound at different temperatures. The diffusivity of Mn was found to be significantly faster than the Ni diffusivity in all single phase structure regions. More than one order of magnitude diffusivity change was observed upon the fcc ↔ B2 transition. The activation enthalpy of Ni self-diffusion in the disordered fcc phase is almost 90 kJ/mol higher than the corresponding value for Mn. In the B2 phase there is only a slight difference between the activation enthalpies of the components which lies within the error bars. A comparison of the present experimental data on tracer self-diffusion with literature data on interdiffusion in the Ni-Mn system shows good agreement between experimental interdiffusion coefficients and those deduced using the Darken-Manning equation from the present tracer diffusion coefficients. The thermodynamical factor was found to vary from 3 to 4 depending on the structure.