The effect of temperature and strain rate on the interactionbetween an edge dislocation and an interstitial dislocation loop inα-iron

Abstract

The influence of temperature, T, and strain rate, , on the reaction between the edge dislocation line and a periodic row of 4 nm interstitial dislocation loops with Burgersvector in α-Fe has been investigated by means of molecular dynamics, using a potential developed recently forbody centred cubic Fe (Ackland et al 2004 J. Phys.: Condens. Matter 16 1). A dislocation segmentwith b = [010] is formed by favourable reaction in all cases: it is sessile in the glide plane and leads to the formation of a screw dipole on the line under increasing stress. Themechanism controlling line breakaway and the corresponding critical stress depend mainly onT rather than . At high T (300 and 600 K here) the length of the screw dipole is short(<10b) and the controlling mechanism is the glide of the [010] segment over the loop surface coupledwith cross-slip of the short screws. The loop is totally absorbed on the line by transformation ofb to . At low T, where thermal effects are negligible, a long(∼100b) screw dipole is drawn out and the controlling mechanism is annihilation of the dipole byscrew cross-slip. This results in only partial absorption of the loop. By comparing theresults with earlier ones obtained using an older interatomic potential, conclusions aredrawn on the effects of interaction between edge dislocations and interstitial loops in iron.