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Disordering of FeAl by Mechanical Milling

1996; Trans Tech Publications; Volume: 235-238; Linguagem: Inglês

10.4028/www.scientific.net/msf.235-238.535

1662-9760

Luke S.-J. Peng, Gary S. Collins,

Advanced Materials Characterization Techniques

Point defect concentrations in milled samples of stoichiometric FeAl were obtained by Msssbauer measurements. Msssbauer spectra consisted of a single absorption dip with broadening attributed to unresolved hyperfine interactions. A local environment model was used to analyze spectra that allowed for defect-induced changes in monopole interactions at Fe probe atoms due to elementary defects in the two nearest atomic shells. It was found that pre-existing vacancies on the Fe sublattice disappear rapidly in the first five minutes of milling, with a corresponding rapid increase in the concentration of antisite-atom pairs. This behavior is very different to that observed in this laboratory for PdIn, using PAC, where vacancies are the principal defect produced. The difference is attributed to a lower energy of ordering for FeAl. A stationary state was observed after 10 minutes of milling, in which the mole fraction of antisite atoms, the average lattice parameter, and the monopole interactions of defect-free probes all ceased to change further. The mole fraction was observed to become stationary at about 10 atomic percent.