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Hier finden Sie wissenschaftliche Publikationen aus den FraunhoferInstituten. Atomistically enabled nonsingular anisotropic elastic representation of nearcore dislocation stress fields in alphairon
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Postprint urn:nbn:de:0011n3435077 (1.2 MByte PDF) MD5 Fingerprint: 3c88c1e9d9fa78792b23a7bbeff3bf4e Erstellt am: 27.9.2016 
 Physical Review. B 91 (2015), Nr.18, Art.184102 ISSN: 01631829 ISSN: 10980121 ISSN: 05562805 
 Deutsche Forschungsgemeinschaft DFG La1974/22 
 Deutsche Forschungsgemeinschaft DFG La1974/31 
 Deutsche Forschungsgemeinschaft DFG Gu367/36 

 Englisch 
 Zeitschriftenaufsatz, Elektronische Publikation 
 Fraunhofer IWM () 
 theories and models of crystal defects; metals ; alloys; linear defects; dislocations; disclinations 
Abstract
The stress fields of dislocations predicted by classical elasticity are known to be unrealistically large approaching the dislocation core, due to the singular nature of the theory. While in many cases this is remedied with the approximation of an effective core radius, inside which ad hoc regularizations are implemented, such approximations lead to a compromise in the accuracy of the calculations. In this work an anisotropic nonsingular elastic representation of dislocation fields is developed to accurately represent the nearcore stresses of dislocations in alphairon. The regularized stress field is enabled through the use of a nonsingular Green's tensor function of Helmholtztype gradient anisotropic elasticity, which requires only a single characteristic length parameter in addition to the material's elastic constants. Using a magnetic bondorder potential to model atomic interactions in iron, molecular statics calculations are performed, and an optimization procedure is developed to extract the required length parameter. Results show the method can accurately replicate the magnitude and decay of the nearcore dislocation stresses even for atoms belonging to the core itself. Comparisons with the singular isotropic and anisotropic theories show the nonsingular anisotropic theory leads to a substantially more accurate representation of the stresses of both screw and edge dislocations near the core, in some cases showing improvements in accuracy of up to an order of magnitude. The spatial extent of the region in which the singular and nonsingular stress differ substantially is also discussed. The general procedure we describe may in principle be applied to accurately model the nearcore dislocation stresses of any arbitrarily shaped dislocation in anisotropic cubic media.