Twin roll casting of bulk amorphous alloys: modelling and experimental validation

There is a growing commercial need for semi-finished flat bulk metallic glass product (BMG), in sheet or strip form, for further shaping into components or containers by forming when in the supercooled liquid state. It has been shown tha ttwin roll casting is a viable method to continuously produce flat amorphouse allow strip of a few mm in thickness. However the process has to be carefully designed and controlled to ensure successful production of a fully amorphous product. To assist with the design of experiments, a steady state model of twin roll casting of BMGs has been developed and used to simulate the continuous casting a Mg65Cu25Y10 alloy. The alloy's thermophysical properties were measured to ensure reliable modelling. Twin roll casting experiments were carried out to assess the validity of the model simulations. The model predicted that it would be possible to roll cast the alloy to a thicness of 1.5 mm at speeds of up to 7cm/s using Cu-Be rolls of 190 mm diameter. This was found to be in good agreement with the outcome of the twin roll casting trials which successfully produced fully amorphous strip at these parameter settings.