单相准晶的生成
(西北工业大学 凝固技术国家重点实验室， 西安 710072)
摘 要: 采用惰性形核涂层型壳和氩气保护下循环过热的深过冷方法， 系统研究了深过冷条件下Al72Ni12Co16合金的凝固组织演化过程及单相准晶的生成条件。 结果表明： 在0～200K的过冷度范围内， 随过冷度的增大， Al72Ni12Co16合金发生小过冷树枝晶→柱状晶→等轴晶的组织转变， 转变的两个临界过冷度分别为ΔT1＝60K和ΔT2＝120K； 此外， 当熔体过冷度大于60K时， 准晶相在与晶体相的竞争形核中胜出， 作为初始相从熔体中析出， 并随过冷度的增大， 凝固组织逐渐变为单相准晶。
关键字: 准晶； 深过冷； 组织演化
of highly undercooled Al72Ni12Co16 alloy
（State Key Laboratory of Solidification Processing，
Northwestern Polytechnical University， Xian 710072， China）
Abstract:The microstructure evolution of Al72Ni12Co16 alloy under the condition of high undercooling was systematically studied by the method of the nucleation-inhibitive coating mold and recycle superheating under Ar atmosphere. The result indicates that with the increase of undercooling， the microstructure of Al72Ni12Co16 alloy will undergo the transformation of dendrite-columnar crystal-equiaxed crystal， and the two critical undercoolings for the transformation are 60K and 120K respectively. And quasicrystalline phase will precipitate from the melt as the primary phase when the undercooling of Al72Ni12Co16 melt is more than 60K， and with the increase of undercooling， the microstructure trends gradually to single phase quasicrystal.
Key words: quasicrystal； high undercooling； microstructure evolution
