Positron Studies of Annealing Processes in Nickel and Gold.
Abstract
Available from UMI in association with The British Library. Requires signed TDF. The work described in this thesis is concerned with the study of the annealing processes in deformed and quenched nickel and gold by the positron annihilation technique. The general theoretical and experimental aspects of the technique are described in Chapters 2, 3 and 4. Chapter 5 gives a brief account of the experimental procedures for the creation and examination of non-equilibrium defects. The different defect recovery stages in metals are discussed in Chapter 6, together with the annealing patterns of the various measured deformed and quenched samples, in terms of the relevant recovery mechanisms. Measurements of the recovery patterns for deformed nickel and gold show a two stage process, representing vacancy migration and recrystallisation, whereas a far more complex process is observed after quenching. Evidence of vacancy clustering is registered for all quenched specimens, but those using hydrochloric acid as a quenching medium show an additional recovery stage. A conjecture involving contamination of the samples with hydrogen is presented for both nickel and gold. Furthermore, an explanation of the recovery pattern for quenched gold involving the possible formation of stacking fault tetrahedra is also discussed.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 1989
- Bibcode:
- 1989PhDT.......143B
- Keywords:
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- Physics: Condensed Matter; Engineering: Metallurgy