Interactions between Edge Dislocations and Interstitial Clusters in Iron and Copper
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Interactions between Edge Dislocations and Interstitial Clusters in Iron and Copper Yu.N. Osetsky1*, D.J. Bacon1, A.Serra2 and B.N.Singh3 1)
Materials Science and Engineering, Department of Engineering, The University of Liverpool, Liverpool L69 3GH, UK 2) Dept. Matemàtica Aplicada III, Universitat Politècnica de Catalunya, Jordi Girona 1-3, E-08034 Barcelona, Spain. 3) Materials Research Department, Ris¡ National Laboratory, P.O.Box 49, DK-4000 Roskilde, Denmark ABSTRACT Dislocations decorated by both clusters of self-interstitial atoms (SIAs) and small dislocation loops, are one of the microstructure features which can play an important role in post-irradiated deformation processes. The interactions between dislocations and clusters are important and are usually treated within the framework of isotropic elasticity theory. However, it is still not clear whether or not these interactions, especially for small clusters at short distances, can be treated accurately by elasticity theory. Comparative studies by atomistic simulation and elasticity theory can clarify this. Here we present a simple example of such a study where interactions between a glissile SIA cluster and an edge dislocation are studied in bcc-Fe and fcc-Cu using both techniques. In Fe we have studied the interaction of a dislocation with Burgers vector b = ½ lying along direction with a SIA cluster with the same b situated at different distances below the extra half-plane. In Cu, the dislocation and cluster had b = ½ and the dislocation line was along the direction. Interactions with clusters of diameter about 1nm were simulated. Elastic calculations were made within the isotropic theory with parameters estimated from atomistic simulation. The results obtained by both techniques are discussed and some preliminary conclusions for different cases are drawn. INTRODUCTION In recent years, results of atomic-scale computer modelling of displacement cascades in metals (see [1] for reviews) and the theoretical treatment known as the production bias model [2] have emphasised the significance of intracascade clustering of self interstitial atoms (SIAs) and one-dimensional (1-D) mass transport by SIA clusters. One of the consequences of the formation of glissile SIA clusters is the creation of a vacancy supersaturation, which leads to void swelling. Another important consequence of the 1-D glide of SIA clusters is the creation of a specific microstructural feature in neutron-irradiated metals, such as decoration of dislocations by SIA loops [3-8]. According to the cascade-induced source hardening model [7-9], the increase in the upper yield stress during neutron irradiation occurs because most grown-in dislocations are locked due to decoration by small SIA clusters and dislocation loops. Dislocation-loop interactions [7-8] and their effect on dislocation dynamics [9] are usually treated in terms of elasticity theory. However, it is still not clear whether or not dislocation-loop and loop-loop interactions, especially at close distances, can be calculated with en
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