的界面穩(wěn)定性的影響
(1.石油大學(華東)機械系, 257062;2.西北工業(yè)大學材料科學與工程學院，西安 10072)
摘 要: 研究了晶體取向對DD8鎳基高溫合金定向凝固的界面穩(wěn)定性的影響，同時考察了抽拉方式對該晶體取向效應的作用。結果表明，<100>偏離熱流方向的晶粒在平界面區(qū)比<100>與熱流方向一致的晶粒的界面穩(wěn)定性大，而在胞枝轉變區(qū)則相反；以平界面速度、胞晶速度和枝晶速度連續(xù)抽拉及逆過程的速度遞減抽拉對以上結果的影響一致。研究表明，晶體取向對凝固界面穩(wěn)定性的影響是由于液相原子在不同晶面結晶面上沉積時形成的原子鍵不同, 影響了系統(tǒng)自由能的降低，影響了液相原子遷移至固相界面上的有效跳動頻率和固相原子遷移至液相中的有效跳動頻率，影響了液固相界面前沿的溶質分布和成分過冷所致。
關鍵字: 高溫合金 定向凝固 晶體取向 界面
（Mechanical Department, Petroleum University(East China), Dongying 257062, P. R. China;
School of Materials Science and Engineering,Northwestern Polytechnical University Xi'an 710072, P. R. China）
Abstract:The effects of crystal orientation on the interfacial stability in the directional solidification of DD8 nickel based high temperature alloy have been investigated, and meanwhile the effect of withdrawing velocity on the function of crystal orientation in directional solidification has also been studied. Results indicated that in plane-cell transformation region, the interface of the grain whose <100> crystal orientation is 45° away from heat flow orientation is stabler than that whose <100> crystal orientation is in according with heat flow, however, in cell-dendrite transformation region,the results turned out contrarily; the effects of continuous withdrawing process from plane region to cell region and dendrite region on the above results are as same as that of the opposite process from dend rite region to cell region and plane region. It was indicated that the effect of crystal orientation on interfacial stability is because of the different atomic bond number formed in the solidification of liquid atoms on different crystal planes, which affects the decrease of system energy, and affects the effective jump frequency of liquid atom migration to solid interface and solid atom migration to liquid, and finally affects the solute distribution in the front of liquid-solid interface and composition undercooling.
Key words: high temperature alloy directional solidification crystalrientation interface
