Synthesis of intermetallic NiAl compound nanoparticles by pulsed wire discharge of twisted Ni and Al wires

Pulsed wire discharge using twisted Ni and Al wires has been tried to synthesize intermetallic NiAl compound nanoparticles. The effects of wire twisting and gas atmosphere conditions on the constituent phases of the synthesized particles were investigated. Ni and Al wires corresponding to the molar composition ratio of 1:1 were hand-twisted to form twined wires with various twisting number per 25 mm which is the nominal span length between the electrodes. Pulsed large current was applied to the twisted wires set between the electrodes in N2 or Ar atmosphere. The results were discussed based on the deposited energy in the wires which can be evaluated from the voltage and current at the wires. Nanoparticles consisting of almost single-phase NiAl compound were synthesized at limited conditions of the N2 atmosphere and the twisting number range of 5–15 turn per 25 mm. At these conditions, the deposited energy in the wires was higher than the vaporization energy of the wires. At the other experimental conditions, other phases such as Ni2Al3 compound phase and metallic Al phase were detected as well as the NiAl phase. Major experimental results in this study can be explained based on the deposited energy in the wires.