Abstract
Perturbed γ-γ angular correlation spectroscopy was applied to study the structure and properties of point defects near111In probes in quenched and annealed NiAl samples with five compositions in the range cNi=48–52%. Quadrupole interaction signals are analysed in terms of near-neighbor Ni-vacancy and nextnear-neighbor Ni antisite atom defects. Large mono- and divacancy concentrations were observed in all samples after quenching. For cNi<50%, the vacancy defects could not be annealed out (structural defects). For CNi>50%, large quenched-in vacancy concentrations annealed out near 500°C. For cNi=50%, most vacancies annealed out near 500°C, but about 35% of the111In probes retained a trapped monovacancy. This is attributed to a very low value of the formation enthalpy of a vacancy next to the In probe, estimated to be 0.16(2) eV. A lesser annelaing stage detected at 300°C is tentatively attributed to diffusion of Al-vacancies.
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Supported by National Science Foundation grant DMR 86-19688 (Metallurgy Program).
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Fan, J., Collins, G.S. Point defects in NiAl near the equiatomic composition. Hyperfine Interact 60, 655–658 (1990). https://doi.org/10.1007/BF02399838
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DOI: https://doi.org/10.1007/BF02399838