ATOMIC SHORT-RANGE ORDERING IN AU-FE ALLOYS - A RESISTOMETRIC STUDY

Kinetics and equilibrium of atomic short-range order (SRO) in Au1-x-Fex (x = 0.05, 0.10, 0.14, 0.20) have been investigated by measurement of residual electrical resistivity for a cold-rolled and a well-annealed state. Activation enthalpies of SRO relaxation correspond well to the sum of formation and migration enthalpies of vacancies, both determined separately. In contrast to Mossbauer measurements a strong temperature dependence of SRO-induced electrical resistivity was observed. It was found that, because of the high density of vacancy sinks, SRO kinetics in the cold-rolled state is considerably slower than in the well-annealed state. Surprisingly, the as-rolled state for the alloys with 5, 10 and 14 at.% Fe has a high degree of SRO, whereas for Au-0.2at%Fe the initial state is disordered. No indications for precipitation of alpha-Fe were found for the samples with 5, 10 and 14 at.%Fe, for both the cold-rolled and the recrystallized state. For 20 at.% Fe, however, a resistivity drift in the cold-rolled state was observed, which may be caused by precipitation of alpha-Fe.