M.I. Kurkin

Segregation of 57Co Atomic Probes in the Cores of Grain Boundaries in d-Transition Metals

A new method, which has been developed to examine the structure and physical properties of cores of grain boundaries (GBs) (S.M. Klotsman, Sov. Phys. Uspech. 33, 55 (1990); V.N. Kaigorodov and S.M. Klotsman, Phys. Rev. B 49 (1994)), was used to study segregats localized in two discrete regions of polycrystals: cores of GBs and two-dimensional regions of the lattice adjacent to the GBs. This paper reports and discusses results of investigations of segregation of 57Co atomic probes in cores of GBs in the d-transition metals Cr, Ta and W. The interaction of 57Co APs with GBs cores in metals is similar to their interaction with vacancies, because GBs cores are characterized, as vacancies in metals, by an excess volume and a negative charge. GBs are enriched with 57Co in chromium and tungsten. The activation enthalpy of the 57Co atomic probes segregation at GBs in Cr and W is proportional tothe local magnetic moment of 57Co atomic probes. GBs cores are found to be depleted of 57Co atomic probes in Ta.