Anomalous bias factors of dislocations in bcc iron

Abstract

Dislocation bias factors in bcc Fe have been calculated based on atomistic interaction energy maps on three kinds of dislocations, namely the a0/2〈111〉{110} screw, a0/2〈111〉{110} and a0〈100〉{001} edge dislocations. The results show that the dislocation bias is higher for the a0/2〈111〉 edge dislocation than for the a0〈100〉 edge dislocation, even though the latter possesses a larger Burgers vector. This indicates the importance of the dislocation core contribution. For the a0/2〈111〉{110} screw dislocation, a negative dislocation bias has been obtained, which implies a more efficient absorption of vacancies than of SIAs. The effect of coexistence of both edge- and screw dislocations are assessed by a total bias. A possible complementary mechanism for explaining the long swelling incubation time in bcc metals is suggested and discussed.