The nucleation of dislocations, and their subsequent propagation during thin-film deposition, were studied by using 3-dimensional molecular dynamics methods. The case of W on a substrate of the same material was investigated. The substrate was under uniaxial compression along the [111] direction, with the thermodynamically favored (0¯11) surface horizontal. The simulation results indicated that nucleation began at a surface step where an atom was squeezed into the layer above; thus generating a half-dislocation loop at the surface. It could then either propagate into the film or become the base of a sessile dislocation loop. In the former case, the dislocation loop (with a Burgers vector of ½[1¯1¯1] on a (101) glide plane) propagated along the [1¯1¯1] direction at the surface and extended to about 2 atomic layers along the [111] direction. In the other case, the missing layer propagated along the [100] direction at the surface; extending to about 4

atomic layers along the [111] direction. In this case, the sessile dislocation had a Burgers vector of ½ [¯1¯1¯1] on the (011) plane.

Dislocation Nucleation and Propagation during Thin Film Deposition under Compression. W.C.Liu, S.Q.Shi, H.Huang, C.H.Woo: Computational Materials Science, 2002, 23[1-4], 155-65

 Table 10

 Diffusivity of Fe in Zr46.8Be27.5Ti8.2Cu7.5Ni10