Influencing factors and estimation of the cooling rate within an amorphous ribbon

Heat transfer during rapid solidification processing of a ribbon prepared by melt spinning can be approximately modeled by a one-dimensional heat conduction equation. The temperature distribution and the cooling rate within the ribbon are determined by integration of the equation. According to the integration function, the cooling rate is in inverse proportion to the square of the thickness of the ribbon. Other factors influencing the cooling rate are also discussed. The thermal diffusivity of the melt material and the coefficient of thermal storage of the cooling wheel are the most important factors that decide the cooling rate of the ribbon. In order to get a higher cooling rate, a cooling wheel with larger coefficient of thermal storage and one kind of material with higher thermal diffusivity are preferred. When molten liquid of a 50 μm thick magnesium ribbon solidifies, the calculated cooling rate at the free surface of the ribbon is up to 5.85×106 °C/s.