Solute diffusion controlled dendritic growth under high undercooling conditions

Liquid Cu70Co30 alloy is undercooled up to 363 K (0.22 T-L) by using glass- fluxing technique. The LKT/BCT dendritic growth theory is modified and made applicable to predict the kinetic characteristics of dendritic growth in t hose alloy systems which have extremely curved liquidus and solidus lines, Actual calculations reveal that the dendritic growth of primary alpha-Co ph ase in Cu70Co30 alloy is constantly controlled by solute diffusion. The gro wth velocity of alpha-Co dendrite has a maximum value of 54.5 mm/s at an un dercooling of 333 K. The calculated solubility of Cu in alpha-Co dendrite d ecreases with the increase of undercooling, which agrees well with the expe rimental data. Prior to peritectic transformation, the growth of alpha-Co d endrite is close to equilibrium solidification.