Non-equilibrium solidification of undercooled Ni-31.44%Pb monotectic alloy melts

来源期刊：中国有色金属学报(英文版)2002年第1期

论文作者：郑红星 谢辉 郭学锋

文章页码：38 - 42

Key words：high undercooling;Ni-Pb monotectic alloy;structural evolution; granulation mechanism

Abstract: By using the method of molten glass denucleating combined with superheating cycling,solidification behavior of the bulk undercooled Ni-31.44%Pb monotectic alloy melts was systematically investigated.The results indicated that the und ercooled monotectic alloy solidifies in form of dendrite essentially during the stage of rapid solidification and after recalescence,the residual melts between the dendrites solidify in the equilibrium mode. Within the achieved undercooling range, the solidification structures are classified into three categories.When the undercooling is less than 50K,the structures are composed of coarse dendrites and interdendritic lead phase. With the undercooling increasing into the range of 70～232K,the dendrite clusters are refined and fine lead particles separate out from the supersaturated primary dendrite arms because of solute trapping. When the undercooling exceeds 242K,the granular grain s form and fine lead particles homogeneously distribute in the whole sample. Bas ed on the observation of the solidification structures and the calculated result s with BCT model, it is found that the granulation mechanism of the granular grains is owing to the primary dendrite disintegration and recrystallization.