采用熔融玻璃净化与循环过热相结合的方法研究了过冷Ni-2Pb单相偏晶合金的组织粒化机制。 在22～280 K过冷度范围内， Ni-2Pb合金组织发生两次粒化。 当22 K<ΔT<66K时， 合金组织由普通树枝晶渐变为第一类粒状晶； 当ΔT>88K时， 合金组织由第一类粒状晶转变为深过冷树枝晶； 当ΔT>187K时， 合金组织骤然粒化为第二类粒状晶。 BCT模型分析表明： 第一类粒状晶的粒化机制为枝晶熔断再结晶机制； 第二类为枝晶碎断再结晶机制。
By using molten glass purification and superheating cycle， granulation mechanisms of undercooled Ni-2Pb single-phase monotectic alloy were studied systematically. Within the achieved undercooling range of 22 to 280K， the solidification structure underwent three changes at 22K， 88K and 187K， respectively. With the increase of undercooling， common dendrites， the first granular grains， undercooled dendrites and the second granular grains came out one after the other. Analytical results show that the granulation mechanism of the first granular grain is owing to dendrite remelting and recrystallizing， and the second is owing to dendrite breaking-up and recrystallizing.
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