An investigation of vacancy-like defects in stoichiometric NiAl by means of positron annihilation measurements

Journal Article · Fri Dec 11 04:00:00 EST 1998 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(98)00354-1· OSTI ID:328271

Puff, W; Logar, B ^[1]; Balogh, A G ^[2]

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1. Technische Univ. Graz (Austria). Inst. fuer Technische Physik
2. Technische Hochschule Darmstadt (Germany). FB Materialwissenschaft

Vacancy-like defects in stoichiometric NiAl are investigated by means of positron lifetime and Doppler-broadening measurements after quenching from high temperatures and proton or electron irradiation. The lifetime of the annealed samples, {tau} = 178 ps, confirms that remnant defects, most probably vacancies and vacancy complexes, are quenched-in during the production of the samples. The decrease of the positron lifetimes and the S-parameter values with increasing quenching temperature are explained with the increasing concentration of Al vacancies. The isochronal annealing of the samples, quenched from 1600 C, shows a distinct agglomeration of defects in the temperature range 400--800 C. After proton and electron irradiation no change in the positron lifetime is observed. There is an annealing stage in the temperature range 900--1200 C. The S-parameter after proton irradiation shows an additional annealing step at around 200 C. Long-time annealing for 520 h at 1150 C does not result in a remarkable reduction of the positron lifetime.

• OSTI ID: 328271
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 1 Vol. 47; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
ANNEALING
ANNIHILATION
INTERMETALLIC COMPOUNDS
LIFETIME
NICKEL ALLOYS
POINT DEFECTS
POSITRONS
TEMPERATURE DEPENDENCE