單相準晶的生成
(西北工業(yè)大學 凝固技術(shù)國家重點實驗室， 西安 710072)
摘 要: 采用惰性形核涂層型殼和氬氣保護下循環(huán)過熱的深過冷方法， 系統(tǒng)研究了深過冷條件下Al72Ni12Co16合金的凝固組織演化過程及單相準晶的生成條件。 結(jié)果表明： 在0～200K的過冷度范圍內(nèi)， 隨過冷度的增大， Al72Ni12Co16合金發(fā)生小過冷樹枝晶→柱狀晶→等軸晶的組織轉(zhuǎn)變， 轉(zhuǎn)變的兩個臨界過冷度分別為ΔT1＝60K和ΔT2＝120K； 此外， 當熔體過冷度大于60K時， 準晶相在與晶體相的競爭形核中勝出， 作為初始相從熔體中析出， 并隨過冷度的增大， 凝固組織逐漸變?yōu)閱蜗鄿示А?nbsp;
關(guān)鍵字: 準晶； 深過冷； 組織演化
of highly undercooled Al72Ni12Co16 alloy
WANG Jin-cheng， SONG Guang-sheng
（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
