Melt instability and crystallization in thin amorphous Ni–P films

Abstract

High-speed TEM (exposure time 10 ns and frame propagation time ≥20 ns) was applied to study hydrodynamic instabilities and crystallization of melt pools produced by focused 5 ns laser pulses in amorphous Ni 1− X P X films ( X=0.2…0.3). Melt flow starts within 15 ns after the laser pulse and accumulates material at the center. The displacement of the liquid continues for several 100 ns. A texture with a non-monotonous distribution of crystal size and with a gradient in composition, containing lattice planes, which occur in Ni–P compounds of a broad range of composition, is produced within 15 μs.