Simulation of damage evolution and accumulation in vanadium

Abstract

Simulation of Damage Evolution and Accumulation in VanadiumE. Alonso M.-J. Caturla T. Díaz de la Rubia J.M. Perlado February 8, 1999This is an informal report intended primarily for internal or limited external distribution.

Molecular Dynamics Simulations of Displacement Cascades in Molybdenum

“…A value between 1/4 and 1/3 seems to be a reasonable approximation to use for the production efficiency needed by rate theory calculations of point defect balance and microstructural evolution. These observations are consistent with simulations performed on other pure metals [4,6,10], and suggest that cascade efficiency itself is probably not strongly system dependent in monatomic metals. This insensitivity is not unexpected since cascade evolution is largely governed by close range interactions that can be treated as binary collisions.…”

“…Clustering of both interstitials and vacancies appears to be less pronounced than in MD simulations of FCC materials such as Au [3]. A smaller tendency to cluster is consistent with previous simulations in other bcc metals [6,10,20].…”

“…Three-dimensional periodic boundary conditions were applied to the computational cells and the cell dimensions were scaled to account for thermal expansion. Computational cell size was selected in accordance with previous work done on other systems [6,7] and to minimize any size effect that would result from temperature increases due to the dissipation of the PKA's kinetic energy. Cell size is given in Table 1.…”

“…Key quantities that must be determined are the number of interstitials and vacancies produced in the cascades and the extent to which the defects cluster together during and immediately following the cascade event. Molecular dynamics (MD) simulations have been used to conduct detailed investigations of displacement cascades in a number of metallic and semiconductor systems [1][2][3][4][5][6][7][8]. The purpose of this paper is to report on molecular dynamics simulations of cascades in molybdenum.…”

Point defect dynamics in bcc metals

“…Starting from the elementary processes mentioned above 7 , steadystate rate equations have been used to study the effects of preferential absorption of self-interstitial atoms at sinks (absorption bias) 8,9 , the formation of interstitial cluster during the cascade phase (production bias) 8,9,10,11 , and the one-dimensional motion of these clusters in bcc metals 9,10,11 . kMC models were first used to evolve the primary damage state obtained from ns-long MD simulations to macroscopic time scales, but have increasingly been used to study the evolution of defect structure during continuous irradiation in copper 12,13,14 , vanadium 15 and iron 16 . Although many treatments have included a high level of atomistic detail from the start, we begin by analyzing the simplest situation that includes only production of Frenkel pairs, point defect recombination and absorption at sinks in Section II.…”