Anomalous bias factors of dislocations in bcc iron

Dislocation bias factors in bcc Fe have been calculated based on atomistic interaction energy maps on three kinds of dislocations, namely the a 0 /2 〈 1 1 1 〉 {1 1 0} screw, a 0 /2 〈 1 1 1 〉 {1 1 0} and a 0 〈 1 0 0 〉 {0 0 1} edge dislocations. The results show that the dislocation bias is higher for the a 0 /2 〈 1 1 1 〉 edge dislocation than for the a 0 〈 1 0 0 〉 edge dislocation, even though the latter possesses a larger Burgers vector. This indicates the importance of the dislocation core contribution. For the a 0 /2 〈 1 1 1 〉 {1 1 0} 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.