SOLUTE-ATOM SEGREGATION AND TWO-DIMENSIONAL PHASE TRANSITIONS IN STACKING FAULTS : AN ATOM-PROBE FIELD-ION MICROSCOPE STUDY

R. Herschitz , D. Seidman , A. Brokman

The atom-probe field-ion microscope has been employed to study solute-atom segregation effects to individual stacking faults in Co-0.96 at.% Nb and Co-0.98 at.% Fe alloys. The compositions of stacking faults have been measured in these alloys in the temperature range 450 to 575°C. The mean solute concentration in the stacking faults decreases with increasing temperature. Small temperature-dependent solute-rich fluctuations (~5 to 20 A diameter), whose compositions differ significantly from the average fault compositions, have been observed in the plane of the stacking fault. The temperature dependence of these fluctuations suggests that in addition to solute-atom segregation we have observed a two-dimensional phase transition in the stacking fault. A Fowler-Guggenheim type segregation isotherm has been derived, which semi-quantitatively explains the temperature dependence of the mean composition of a fault.

Domaines: Articles anciens

R. Herschitz, D. Seidman, A. Brokman. SOLUTE-ATOM SEGREGATION AND TWO-DIMENSIONAL PHASE TRANSITIONS IN STACKING FAULTS : AN ATOM-PROBE FIELD-ION MICROSCOPE STUDY. Journal de Physique Colloques, 1985, 46 (C4), pp.C4-451-C4-464. ⟨10.1051/jphyscol:1985450⟩. ⟨jpa-00224701⟩