Amorphous layer formation on nickel alloy surface by intense pulsed ion beam irradiation

The formation of an amorphous layer due to irradiation of intense pulsed ion beams (PIBs) has been studied experimentally. A mixed carbon and fluorine PIB with energy of 180 keV, ion beam current density of 180 A/cm(2) and pulse duration of 30 ns is irradiated on a Ni65Cr15P16B4 alloy, resulting in the formation of an amorphous layer on the substrate surface to a depth of 0.66 mu m which is consistent with the thermal diffusion length. Repeated irradiations of PIB lead to the formation of an amorphous phase at depths exceeding 0.66 mu m from the surface. PIB irradiation leads to rapid heating of the substrate surface to its boiling point (2732 degrees C), and the cooling rate from the melting point to the glass transition point is estimated to he 2.2 x 10(9) degrees C/s which is larger than the critical cooling rate for amorphous layer formation of nickel alloys.