Size-dependent energy capture and wave-driven evolution of a prismatic Frank dislocation loop under a nonlinear supratransmission wave in the Pt₃Al intermetallic: an atomistic study

The interaction of a supersonic solitary wave generated by nonlinear supratransmission (NST) with a vacancy {111} Frank dislocation loop is studied by molecular dynamics in the L1₂-ordered intermetallic Pt₃Al. Three loop radii (R = 8, 12, 16 Å) and five source amplitudes (A = 0.18–0.50 Å) are examined near zero temperature with an embedded-atom potential. Fault energies and a chemical census show that the loop encloses a superlattice intrinsic stacking fault bounded by a chemically disordered rim. The loop is nearly transparent to the pulse: the peak transmission stays within 3% of unity and the integrated transmission falls by at most 8%. The loop retains a residual energy whose potential part grows with the fault area, ΔUcap ∝ R². This energy is vibrational, equipartitioned and densest at the loop, and it persists until the end of the simulation. Atom-resolved tracking relative to the lattice separates the residual displacement left by the pulse, up to 16 Å, from changes of the loop itself. Below a threshold, reached only for R = 16 Å at A = 0.50 Å, the loop rides with the lattice unaltered. Above it the stacking fault keeps its plane and, at T ≈ 0, its order, while the pulse generates Frenkel-type pairs at the rim and a zone of distorted crystal with Al–Al bonds attached to it. At 300 K this zone grows, with more than two hundred atoms changing their lattice sites. Two thermal controls without the wave show none of these changes.