-Equilibrium distributions of collections of discrete dislocations are analyzed, with the dislocations modelled as line defects in a linear elastic medium. The dislocated equilibrium configuration is determined by finding a minimum potential energy configuration, with respect to variations in the dislocation positions, for a fixed number and type of dislocations. Numerical results are presented...

We study the topological structure of the SU(2) vacuum at zero temperature: topological susceptibility, size, shape and distance distributions of the instantons. We use a cooling algorithm based on an improved action with scale invariant instanton solutions. This algorithm needs no monitoring or calibration, has an inherent cut off for dislocations and leaves unchanged instantons at physical sc...

Transmission electron microscopy (TEM) is carried out to characterize the extended defect reduction in low-defect nonplanar GaN substrate templates grown by lateral epitaxial overgrowth (LEO). The LEO nonplanar GaN substrate template has a trapezoidal cross section with smooth (0 0 0 1) and f1 1 2̄ 2g facets. We demonstrate here the dislocation distribution and behavior in both ordinary LEO and ...

A dislocation is a crystallographic defect, or irregularity, within a crystal structure. The presence of dislocations strongly influences many of the properties of materials. The theory was originally developed by Vito Volterra in 1905, but the term 'dislocation' was not coined until later by the Professor Sir Frederick Charles Frank of the Physics Department at the University of Bristol. In 19...

M. Mihaliková, A. Lišková, Faculty of Metallurgy, Technical University of Košice, Slovakia The aim of this experimental research was to perform an analysis of deformation characteristics on two different types of steel: IF steel, and micro-alloyed steel were used automotive industry. For that purpose changes of properties of these materials were carried out by static 10-3 · s-1 and dynamic 103 ...

A non-equilibrium theory of isothermal and diffusionless evolution of incoherent interfaces within a plastically deforming solid is developed. The irreversible dynamics of the interface are driven by its normal motion, incoherency (slip and misorientation), and an intrinsic plastic flow; and purely by plastic deformation in the bulk away from the interface. Using the continuum theory for defect...

Deformation mechanisms of a fully lamellar TiAl (γ lamellae: 100 ~ 300Ênm thick, α2 lamellae: 10 ~ 50 nm thick) crept at 760¡C have been investigated. It was found that, as a result of a fine structure, the motion and multiplication of dislocations within both γ and α2 lamellae are limited at low creep stresses (< 400 MPa). Thus, the glide and climb of lattice dislocations have insignificant co...

A new computer simulation method based on stochastic integration of the Langevin equations of dislocation motion is proposed for the investigation of the dynamic properties of a system of parallel straight dislocations. The stochastic approach developed for weakly correlated dislocation systems allows for more than 106 dislocations in the simulation area. Relaxation of a system of 220 parallel ...