Abstract
Cu-8mass%Sn alloy was quenched in water at various stages during freezing to interrupt further dendrite growth. Fraction solid was measured by an image analyzer as a function of temperature. Fraction solid increased remarkably in the initial stage of solidification at temperature down to approximately 15K below liquidus, at which both nucleation and linear growth of dendrite are completed, and gradually increases thereafter. The fraction solid as a function of temperature can be calculated with fair accuracy by means of Kirkwood's method using the value of fraction solid determined experimentally in the initial stage of solidification. When cooling rate is accelerated, a number of smaller dendrite cells form, the solid-liquid interface extends and fraction solid increases more remarkably. Rate of increase of fraction solid is independent of dendrite morphology.
