Specimens of pure Fe, Fe-0.15wt.%Cu and Fe-0.6wt.%Cu were deformed with 10% strain by three deformation modes (rolling, compression and tension), and were measured using positron annihilation spectroscopy after annealing from 373 K to 873 K per 100 K for 1 hour. The positron annihilation lifetime of vacancies after deformation was about 135 psec, and most of the vacancies produced by deformation were expected to be trapped at the dislocation core, and were released from it at 573 K. In Fe-0.15%Cu, Cu precipitates were not produced, and the formation and annihilation behavior of vacancies was similar to pure Fe. In each deformation, cell structures were different, so, in the Fe-0.6%Cu, growth of Cu precipitates was different. The tension, rolling and compression were ranked in a descending order of degree of contribution of the vacancies released from the dislocations to the growth of Cu precipitation.

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