Peritectic solidification under high undercooling conditions  

作　　者：Chongde Cao Xiaoyu Lu Bingbo Wei 

机构地区：[1]Northwestern Polytech Univ, Dept Appl Phys, Xian 710072, Peoples R China

出　　处：《Chinese Science Bulletin》1999年第14期1338-1343,共6页

摘　　要：The solidification characteristics of highly undercooled Cu-7.77% Co peritectic alloy has been examined by glass fluxing technique. The obtained undercoolings vary from 93 to 203 K(0.14 T_L). It is found that the a(Co) phase always nucleates and grows preferentially, which is followed by peritectic transformation. This means that the peritectic phase cannot form directly, even though the alloy melt is undercooled to a temperature far below its peritectic point. The maximum recalescence temperature measured experimentally decreases as undercooling increases, which is lower than the thermodynamic calculation result owing to the actual non-adiabatic nature of recalescence process. The dendritic fragmentation of primary α(Co) phase induced by high undercooling is found to enhance the completion of peritectic transformation. In addition, the LKT/BCT dendrite growth model is modified in order to make it applicable to those binary alloy systems with seriously curved liquidus and solidus lines. The dendriteThe solidification characteristics of highly undercooled Cu-7.77% Co peritectic alloy has been examined by glass fluxing technique. The obtained undercoolings vary from 93 to 203 K(0.14 TL). It is found that the α(Co) phase always nucleates and grows preferentially, which is followed by peritectic transformation. This means that the peritectic phase cannot form directly, even though the alloy melt is undercooled to a temperature far below its peritectic point. The maximum recalescence temperature measured experimentally decreases as undercooling increases, which is lower than the thermodynamic calculation result owing to the actual non-adia-batic nature of recalescence process. The dendritic fragmentation of primary α (Co) phase induced by high undercooling is found to enhance the completion of peritectic transformation. In addition, the LKT/BCT dendrite growth model is modified in order to make it appllcable to those binary alloy systems with seriously curved liquidus and solidus lines. The dendrite growth velocities of primary α (Co) phase are subsequently calculated as a function of undercooling on the basis of this model.

关 键 词：PERITECTIC SOLIDIFICATION UNDERCOOLING NUCLEATION RECALESCENCE DENDRITE growth. 

分 类 号：TG131[一般工业技术—材料科学与工程]