Amorphous Alloys from Microsecond Current Pulses

Abstract

AbstractWe report the use of microsecond current pulses to produce an amorphous metal alloy. Starting materials consisted of electron beam deposited films of elemental crystalline zirconium and nickel layers with a composition modulation wavelength of 46 nm, a total thickness of about 2.5 μn, and an average composition of Zr38Ni62 deposited onto sapphire substrates. Current pulses had a total ring time of several microseconds and were produced with a low inductance capacitor and a spark gap switch. Integration of current traces showed that 85% of the energy was deposited into the sample within 2 microseconds. The energy in the pulses could be controlled in a range where their effect on the films went from no visible change to total vaporization. Pulses with a peak current in the kiloampere range produced melting in 1 cm wide samples. The cooling rate following this treatment was sufficient to produce amorphous material. We report structural changes resulting from rapid melting and resolidification as well as results of a search for solid state transformations resulting from current pulses below the melting threshold.