Effects of process variables on the multi-strand casting of high strength sub-millimetre metallic glass wire

The casting of amorphous iron-based wires of sub-millimetre diameters have been studied in a multiple jet casting condition. The effects of process parameters; melt jet to water velocity ratio (vr), melt super heat, nozzle diameter, nozzle clearance distance, and alloy composition on the stability of the melt jet and consequently on the quality of the wire has been studied. In order to increase the output rate, a multiple-nozzle crucible was designed for the casting process. Three nozzle designs were considered. It was found that when other cast variables were optimised, the nozzle types affected the flow and coherency of the jet. The best multi-nozzle crucible was made by using laser-drilled quartz platelets. The nozzle spacing did not affect the rapid cooling of the melt jet and thus the amorphous structures in the wires were retained for the closest spacing of 1 mm. It is demonstrated that the use of a multiple-nozzle crucible can effectively be used to increase by many folds the casting rate in the rotating water bath wire casting process.