Dislocation density-based constitutive model for the mechanical behaviour of irradiated Cu

• Published in: Philosophical magazine (Abingdon, England) Vol. 84; no. 34; pp. 3617 - 3635
• Main Authors: Arsenlis §, A., Wirth, B. D., Rhee, M.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis Group 01.12.2004; Taylor and Francis
• Subjects: Condensed matter: structure, mechanical and thermal properties; Defects and impurities in crystals; microstructure; Exact sciences and technology; Neutron radiation effects; Physical radiation effects, radiation damage; Physics; Point defects (vacancies, interstitials, color centers, etc.) and defect clusters; Stacking faults and other planar or extended defects; Structure of solids and liquids; crystallography; Austenitic stainless steel; Stacking faults; Inorganic compounds; Work hardening; Vacancies; Mechanical strength; Physical radiation effects; Digital simulation; Molecular dynamics method; Theoretical study; Polycrystals; Implementation; Dislocation density; Finite element method; Monocrystals; Quantity ratio; Transition elements; Neutron beams; Copper; Transition element alloys
• ISSN: 1478-6435; 1478-6443
• DOI: 10.1080/14786430412331293531

Performance degradation of structural steels in nuclear environments results from the formation of a high number density of nanometre-scale defects. The defects observed in copper-based alloys are composed of vacancy clusters in the form of stacking fault tetrahedra and/or prismatic dislocation loops that impede the motion of dislocations. The mechanical behaviour of irradiated copper alloys exhibits increased yield strength, decreased total strain to failure and decreased work hardening as compared to their unirradiated behaviour. Above certain critical defect concentrations (neutron doses), the mechanical behaviour exhibits distinct upper yield points. In this paper, we describe the formulation of an internal state variable model for the mechanical behaviour of such materials subject to these (irradiation) environments. This model has been developed within a multiscale materials-modelling framework, in which molecular dynamics simulations of dislocation-radiation defect interactions inform the final coarse-grained continuum model. The plasticity model includes mechanisms for dislocation density growth and multiplication and for irradiation defect density evolution with dislocation interaction. The general behaviour of the constitutive (homogeneous material point) model shows that as the defect density increases, the initial yield point increases and the initial strain hardening decreases. The final coarse-grained model is implemented into a finite element framework and used to simulate the behaviour of tensile specimens with varying levels of irradiation-induced material damage. The simulation results compare favourably with the experimentally observed mechanical behaviour of irradiated materials.