Tracer diffusion in amorphous solid is studied by mean of n B -bubble statistic. The n B -bubble is defined as a group of atoms around a spherical void and large bubble that represents a structural defect which could be eliminated under thermal annealing. It was found that amorphous alloys such as Co x B 100−x (x = 90, 81.5 and 70) and Fe 80 P 20 suffer from a large number of vacancy bubbles which function like diffusion vehicle. The concentration of vacancy bubble weakly depends on temperature, but essentially on the relaxation degree of considered sample. The diffusion coefficient estimated for proposed mechanism via vacancy bubbles is in a reasonable agreement with experiment for actual amorphous alloys. The relaxation effect for tracer diffusion in amorphous alloys is interpreted by the elimination of vacancy bubbles under thermal annealing.
The statistical relaxation (SR) simulation has been conducted to study the behavior of simplexes and bubbles (BB) in amorphous Co metal containing 2 × 10 5 atoms. The simulation reveals that the fraction of 4-simplex increases and n-simplex (n > 4) decreases depending upon relaxation degree. The simulation found that a large number of BB vary upon relaxation degree, which could play a role of diffusion vehicle for Co atoms in amorphous matrix. The idea of the diffusion mechanism in amorphous metal is described as follows: the elemental atomic movement includes a jump of neighboring atom into the BB and then a collective displacement of a large number of atoms around BB.
This paper analyzes the known methods and means for measuring the deformation of the windings of large power transformers, as well as the proposed methods for controlling the deformation of windings of large power transformers based on the value of z k in online monitoring in different operating modes of power transformers.
Abstract. Molecular dynamic (MD) simulation is proven to be an important tool to study the structure as well as the physical properties at atomic level in materials science. However, it requires a huge computing time and hence limits the ability to treat a large scale simulation. In this paper we present a solution to speed up the MD simulation using CUDA technology (Compute Unified Device Architecture). We used the GeForce GTS 250 card with Version 2.30. The simulation is implemented for Lennard-Jones systems with periodic boundary conditions which consist of 1024, 2048, 4096 and 8192 atoms. The calculation shows that the computing time depends on the size of system and could be decreased by 37 times. This result indicates a possibility of constructing a large MD model with up to 10 5 atoms on the usual PC.
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