Molecular-dynamical calculations of irradiation-produced point defects in bcc metals

Journal Article · Sat Apr 01 00:00:00 EST 1989 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.39.6381· OSTI ID:6153070

Taji, Y; Iwata, T; Yokota, T; Fuse, M

Molecular-dynamical calculations show that bcc metals are classified into two groups ((Mo, W, Fe) and (V, Nb, Ta)) concerning the configurations of irradiation-produced point defects. The potentials used are those constructed from elastic constants by Johnson and Wilson. In the first group, the stable interstitial produced by irradiation is of the <110>-split type, and the vacancy is of the normal character, where neighboring atoms relax slightly; this result is the same as in the previous works. In the second group entirely different configurations of point defects are produced. As to interstitials, the <100> crowdion is the most stable and the <100> and the <111> split interstitials are stable at absolute zero temperature. The <110> split interstitial is also stable in V. The type of interstitials produced depends on the direction of primary knock-on atoms in the case of near-threshold collisions events. As to vacancies, in addition to the normal vacancy, the nonuniformly shrunken vacancy is produced, where four of the eight nearest neighbors shrink symmetrically by 22% of the equilibrium distance. The shrunken vacancy is more stable than the normal one. The extended vacancy along the <111> direction is also produced. The self-energies and the migration energies of these interstitials and vacancies are also calculated. The above classification of bcc metals originates from the difference in elastic property through the potentials used, and it corresponds with the classification based on such experimental data as the onset temperatures of defect migration and the positron annihilation.

• Research Organization: Department of Physics, Japan Atomic Energy Research Institute, Tokai-mura, Ibaraki-ken 319-11, Japan
• OSTI ID: 6153070
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Vol. 39:10
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
IRON
PHYSICAL RADIATION EFFECTS
MOLYBDENUM
NIOBIUM
TANTALUM
TUNGSTEN
VANADIUM
ABSOLUTE ZERO TEMPERATURE
BCC LATTICES
CROWDIONS
INTERSTITIALS
POINT DEFECTS
POTENTIALS
SELF-ENERGY
STABILITY
VACANCIES
CRYSTAL DEFECTS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CUBIC LATTICES
ELEMENTS
ENERGY
LINE DEFECTS
METALS
RADIATION EFFECTS
TRANSITION ELEMENTS
360106* - Metals &amp; Alloys- Radiation Effects