Mechanisms of hardening due to copper precipitates in α-iron

David John Bacon (1) , Yuri Osetsky (2)

1 Engineering
2 ORNL - Oak Ridge National Laboratory [Oak Ridge]

A comprehensive atomic-level simulation study has been made of interactions between a moving edge dislocation and copper precipitates that are initially coherent with the body-centred-cubic matrix of alpha-iron Precipitates with diameter, D, in the range from 0.7 to 6 nm have been considered over the temperature range from 0 to 600 K. For some combinations of temperature and D, the critical applied resolved shear stress, τc, at which the dislocation overcomes a row of precipitates with centre-to-centre spacing, L, is consistent with an elasticity treatment for strong obstacles, e.g. τc is proportional to L-1 and ln(D). This has a specific atomic-level origin, for the proportionality holds when the dislocation induces a partial transformation of the copper towards the more stable face-centred-cubic phase. The driving force for the transformation increases with decreasing temperature and increasing D, and so τc has a strong temperature-dependence for large D. The results of these simulations, which employ a set of interatomic potentials of Finnis-Sinclair type, are seen to correspond well with experiments carried out elsewhere.

Mots clés: Physical Sciences

David John Bacon, Yuri Osetsky. Mechanisms of hardening due to copper precipitates in α-iron. Philosophical Magazine, 2009, 89 (34-36), pp.3333-3349. ⟨10.1080/14786430903271377⟩. ⟨hal-00541682⟩