2002 Volume 43 Issue 7 Pages 1486-1488
The order-disorder transformation and lattice defects in Ni3Fe have been studied by positron lifetime measurements. Anomalous vacancy-generation during ordering transformation, which was originally found on the ordering process of super-cooled disordered Cu3Au, has been confirmed on the ordering transformation of Ni3Fe. Disordered fcc solid solution of Ni3Fe was brought to room temperature by quenching the specimen from temperatures above the order-disorder transformation point TC. The ordering process into L12 structure was promoted by heating the sample isochronally or isothermally. It has been found that vacancies are generated in both heating processes, i.e., during the ordering process of super-cooled disordered Ni3Fe. Generated vacancies are not stable up to TC and annealed out at temperatures below TC.