Positron-Annihilation Study of the Microstructure Evolution in Deformed Fe-Ni Austenitic Alloys Containing Titanium

摘要

The evolution of the microstructure of cold-worked austenitic Fe-36.5 wt percent Ni alloys free of Ti and containing 2.5 wt percent To was studied. The room-temperature deformation of the alloys was established to cause the migration and clustering of vacancies. The vacancies interact with titanium, and the titanium atoms act as nuclei of vacancy clusters. In the titanium-containing alloys, the positron trapping by dislocations was found to be blocked. This effect is caused by the segregation of titanium atoms and the nucleation of the ＃gamma＃ phase Ni_3Ti at dislocations. The Ni_3Ti precipitates pin dislocations and thus suppress the initial stage of recrystallization upon postdeformation annealing.