Effect of Palladium on the Phase Transformations in Gold-Copper-Palladium Alloys

摘要

Field ion microscopy was used to study the effect of palladium on the phase transformations in the alloys (at. percent) 35.3 Au-52.6 Cu-12.1 Pd and 20.6 Au-55.2 Cu-24.2 Pd. It has been found that an increase in the palladium content not only accelerates the recrystallization of solid solutions in this system but also changes the kinetics of the disorder-order phase transformation. In the alloy with the higher palladium content (24.2 at. percent), atomic ordering of the L1_0 type is realized through the formation of the intermediate metastable phase B2. Experimental data indicating the martensitic mechanism of the B2 reversible L1_0 phase transition in the 20.6 Au-55.2 Cu-24.2 Pd alloy are given. It was found that the palladium atoms are located in the same sublattice as the gold atoms both in the L1_0 and B2 superstructures.