的界面稳定性的影响
(1.石油大学(华东)机械系, 257062;2.西北工业大学材料科学与工程学院，西安 10072)
摘 要: 研究了晶体取向对DD8镍基高温合金定向凝固的界面稳定性的影响，同时考察了抽拉方式对该晶体取向效应的作用。结果表明，<100>偏离热流方向的晶粒在平界面区比<100>与热流方向一致的晶粒的界面稳定性大，而在胞枝转变区则相反；以平界面速度、胞晶速度和枝晶速度连续抽拉及逆过程的速度递减抽拉对以上结果的影响一致。研究表明，晶体取向对凝固界面稳定性的影响是由于液相原子在不同晶面结晶面上沉积时形成的原子键不同, 影响了系统自由能的降低，影响了液相原子迁移至固相界面上的有效跳动频率和固相原子迁移至液相中的有效跳动频率，影响了液固相界面前沿的溶质分布和成分过冷所致。
关键字: 高温合金 定向凝固 晶体取向 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
