Direct measurements of the cooling rates in the single roller rapid solidification technique

Abstract

A thermoelectric technique for the measurement of temperature on the contact side of the liquid pool and ribbon during single roller melt-spinning of Fe40Ni40P14B[6 metallic alloy is described. Evidence is presented that ribbon formation is controlled by momentum transport. Measured cooling rates at the melting point, interface heat transfer coefficients and Nusselt numbers are in the ranges 1.8×105-3.3×106 K/s, 4.5×104-4.5×105 W/(m2 K) and 0.14-0.52, respectively, for roller velocities of 12-25 m/s and ribbon thicknesses of 65-24 μm. It is found that despite the existence of temperature gradients through the ribbon thickness, plots of the cooling rates vs temperature are linear and the values of the interfacial heat transfer coefficients derived from experimental cooling curves using both Newtonian and non-Newtonian heat flow analyses, are very similar.