镍基高温合金定向凝固过程枝晶组织相场模拟研究  

Phase-Field Simulation of Dendrite Growth in Directionally Solidified Nickel-Based Superalloy

作　　者：许庆彦 杨聪 柳百成 XU Qingyan;YANG Cong;LIU Baicheng(Key Laboratory for Advanced Materials Processing Technology,Ministry of Education,School of Materials Science and Engineering,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学材料学院先进成形制造教育部重点实验室

出　　处：《航空制造技术》2019年第19期14-20,共7页Aeronautical Manufacturing Technology

基　　金：国家科技重大专项(2017–Ⅶ–0008–0101、2017–Ⅵ–0003–0073、2017ZX04014001);国家重点研发计划(2017YFB0701503);国家自然科学基金(51374137)

摘　　要：镍基高温合金是一类重要的高温结构材料,其铸态组织尤其是枝晶组织对最终的性能有重要影响。开发了耦合热力学数据库的相场模型,用于模拟多元镍基高温合金的枝晶生长过程。使用了GPU(Graphics Processing Unit)来加速相场计算,以实现大尺度范围下的凝固组织相场模拟。对定向凝固单晶枝晶生长进行了模拟研究,结果表明从基底形成枝晶臂经历了从瞬态生长到稳态生长的过程,且整个过程受到传热与溶质扩散的控制。对定向凝固双晶竞争生长(θ=±15°)进行了模拟研究,其中发散型枝晶生长中择优取向枝晶能竞争掉非择优取向的枝晶使得晶界发生移动,而汇聚型枝晶生长中晶界保持不变。最后研究了自然对流对枝晶生长的影响,并将模拟得到元素偏析结果与试验结果进行了对比,发现吻合较好。The nickel-based superalloy is among the most important high-temperature structural materials,of which the casting microstructure and especially the dendrite structure can a ffect the final performance of the superalloy parts.In this work,the phase-field model was coupled with thermodynamic database to simulate the dendrite growth in the multicomponent nickel-based superalloy solidi fication.And the GPU device was used to accelerate the computation and large-scale phase-field simulations were achieved.The single-crystal dendrite growth was simulated,and the results exhibit a transient and stable growth stages during the formation of primary dendrite arms.The dendrite competitive growth in bicrystal directional solidification(θ=±15°)was also investigated.And the favorable oriented dendrites were able to overgrow the unfavorable oriented dendrites in diverging grain boundary.While the grain boundary remains unchanged in the converging dendrite growth simulation.At last,the effects of natural convection on dendrite growth were investigated,and the simulated microsegregation pattern of the alloy components agreed well with the experimental results.

关 键 词：定向凝固 枝晶生长 高温合金 相场模拟 

分 类 号：TG1[金属学及工艺—金属学]