Positron lifetime study of dislocations in metals

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Positron lifetime measurements have been performed on some fcc metals and alloys, which were treated to be in such specific conditions that only a given type of dislocations are predominantly contained. The results show that the positron lifetime increases monotonously with the magnitude of Burgers vectors of dislocations. When dislocations are actually extended, the observed positron lifetime comes from partial dislocations and is remarkably shorter than that at undissociated dislocations. Present results not only demonstrate that positron annihilation parameters observed predominantly come from dislocation lines themselves but also show that positron lifetime spectroscopy can be used to differentiate between different types of dislocations.