The present paper deals with the research of vacancy clusters stability in fcc metals Ni, Cu, Al by the method of molecular dynamics. The calculated block of an ideal crystal contained 27000 atoms in the model. Periodical boundaries were applied on its block. Interatomic interactions were described by pair central Morse potentials. Vacancy clusters were constructed by the removal of corresponding atoms from the calculated block. The following types of clusters were studied: pores, vacancy discs, stacking fault tetrahedrons, vacancy "tubes", which were constructed by the removal of the part of closely-packed atomic row, accidentally distributed single vacancies. The number of vacancies in every case varied from several units to several hundreds. The annealings of crystal block at the temperature from 0.5Tm to Tm during 100-500 ps with further cooling to the temperature of about 0 K were made to determine clusters stability. Diffusion coefficient and potential energy of the calculated block were calculated after cooling. Studied was the structure of crystal block by the visualizators of a distribution of the potential energy and atomic displacements. Vacancy clusters having tetrahedron form were more stable and energetically profitable. The sides of the tetrahedron were oriented along the planes <111> and looked like stacking fault defects, sides - as partial dislocations oriented along the directions <110>. All the types of the considered vacancy clusters tended to take a tetrahedron form. Similar stacking fault tetrahedra were stable up to the melting temperature. Pores were less energetically profitable than flat clusters. Diffusion at the presence of pores in the crystal took place mainly along the internal surface by so-called "rolling stone" mechanism. It was found that the bigger the size of a vacancy disk or a pore, the less mobilie it was. Consequently, the activation energy of cluster-migration-mediated diffusion was high.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/8113 must be provided.

1. Diffusion Mechanisms near Tilt Grain Boundaries in Ni3Al Intermetallide
2. The research of thermoactivated changes of the structure of antiphase boundaries in Cu3Au and Ni3Al alloys
3. Point defects and their influence on thermoactivated disordering process of Ni3Al intermetallic
4. DIFFUSION MECHANISM AT THE GRAIN BOUNDARIES IN TWO-DIMENSIONAL METALS