董子鸣 张雅姗 何峰 王志军 杨瑞宁 王雷. 碳化物对DD32高温合金激光重熔熔池底部杂晶形成的作用机制[J]. 金属学报, DOI: 10.11900/0412.1961.2025.00151.

摘要 相关文章 Metrics 全文: PDF(1672 KB)   摘要: 镍基单晶高温合金经激光熔凝后，熔池底部易出现杂晶。根据杂晶形成理论，杂晶形成能力反比于柱状晶前沿的温度梯度和柱状晶生长速率的比值，熔池底部因具有高温度梯度和低凝固速率，理论上不利于杂晶形成。熔池底部碳化物提供形核点是杂晶形成的关键因素，但具体机制尚不清楚。为了明确熔池底部碳化物诱导杂晶形成的具体机制，本工作选用C含量高的镍基单晶高温合金DD32为对象，结合组织表征和数值计算研究了碳化物对激光重熔熔池底部杂晶形成的作用机制。结果表明，熔池底部杂晶的形成与碳化物(TaNb)C相关，该碳化物来源于基体本身且在重熔过程中难以完全熔化和溶解，在重力作用下会沉降到熔池底部，增大底部形核点密度。将形核点密度变化与杂晶体积分数计算模型相结合，定量阐明了碳化物导致熔池底部形核点密度增大从而促进杂晶形成的作用机制，为单晶修复过程中的杂晶控制提供了理论指导。 关键词 ： 激光表面重熔,  镍基高温合金,  杂晶,  碳化物,  数值模拟     Abstract：Nickel-based single-crystal superalloys are widely utilized for manufacturing turbine blades in aerospace engines owing to their excellent oxidation and hot-corrosion resistance. However, these components are susceptible to various types of damage under high-temperature conditions, and their high replacement cost makes repair essential. Laser additive manufacturing (LAM) is commonly used for repairing single-crystal blades; however, it often introduces stray grains, which form grain boundaries that degrade the alloy's properties. Therefore, suppressing stray grain formation is a critical objective in the laser repair process. During laser melting, nickel-based single-crystal superalloys are highly prone to stray grain formation at the bottom of the melt pool. According to the stray grain formation theory, the propensity for stray grain formation is inversely proportional to the ratio of the temperature gradient to the growth rate at the columnar dendrite front. As the melt-pool bottom has a high thermal gradient and low solidification rate, stray grain formation should theoretically be suppressed in this region; however, experimental observations yet contradict this prediction. Carbides may act as potent nucleation sites and play a critical role in facilitating stray grain formation at the melt-pool bottom; however, the detailed mechanism remains elusive. To clarify this mechanism, laser remelting was performed on DD32, a high-carbon nickel-based single-crystal superalloy produced in China. Particulate inclusions within the stray grain area at the melt-pool bottom were detected via optical microscopy and subsequently identified as MC-type carbides (TaNb)C via scanning electron microscopy and energy-dispersive X-ray spectroscopy. Their considerable size difference from that of carbides reprecipitated after remelting indicates that they originate from the alloy matrix, and they exhibit resistance to complete melting or dissolution during the remelting process. As these carbides have a considerably higher density than the alloy melt, they settle to the melt-pool bottom due to gravity, thereby increasing the nucleation site density and promoting the formation of stray grains. By integrating electron probe microanalysis (EPMA) with numerical simulation, this study quantitatively elucidated how carbide-induced nucleation sites increase nucleation density at the melt-pool bottom and promote stray grain formation. These findings explain the phenomenon of stray grain formation at the bottom of the laser-melted pool in nickel-based single-crystal superalloys and provide a theoretical basis for controlling stray grains in future single-crystal repair processes. Key words： Laser surface re-melting    Nickel superalloys    Stray grain    Carbide    Numerical simulation 收稿日期: 2025-06-03      服务 把本文推荐给朋友 加入引用管理器 E-mail Alert RSS 作者相关文章 董子鸣 张雅姗 何峰 王志军 杨瑞宁 王雷 44.8K 链接本文: https://www.ams.org.cn/CN/Y0/V/I/0 [1] 张天昊, 鞠泉, 蒙肇斌, 王浩, 胡本芙. GH3230合金薄板填丝钨极氩弧焊接头的组织稳定性[J]. 金属学报, 2025, 61(9): 1375-1386. [2] 谢信亮, 周丽萍, 余建波, 玄伟东, 陈超越, 王江, 任忠鸣. 横向弱磁场对镍基高温合金发散双晶竞争生长行为的影响[J]. 金属学报, 2025, 61(8): 1203-1216. [3] 刘继浩, 迟宏宵, 武会宾, 马党参, 周健, 谷金波. 喷射成形工艺对M3高速钢碳化物特征及力学性能的影响[J]. 金属学报, 2025, 61(8): 1229-1244. [4] 谢昂, 陈胜虎, 姜海昌, 戎利建. Nb含量和均质化处理对奥氏体不锈钢铸态组织和力学性能的影响[J]. 金属学报, 2025, 61(7): 1035-1048. [5] 李夫顺, 刘志鹏, 丁灿灿, 胡斌, 罗海文. 一种新型高强奥氏体低密度钢的强塑性机理[J]. 金属学报, 2025, 61(6): 909-916. [6] 赵广迪, 李阳, 姚晓雨, 王亮, 李渭滨, 潘玉华, 李维娟, 王兆宇. B对Fe-Cr-B-C合金凝固行为、强韧性及耐磨性的影响[J]. 金属学报, 2025, 61(5): 699-716. [7] 周一鸣, 韩勇军, 谢光, 郑伟, 肖炎彬, 潘阳, 张健. 一种镍基高温合金的高温HCl腐蚀行为[J]. 金属学报, 2025, 61(5): 770-782. [8] 梁炫, 侯廷平, 张东, 谭昕暘, 吴开明. 中碳Nb合金化钢液析碳化物的析出行为[J]. 金属学报, 2025, 61(4): 653-664. [9] 邹建新, 张嘉祺, 赵颖燕, 林羲, 丁文江. 高容量镁基储氢合金材料研究与应用进展[J]. 金属学报, 2025, 61(3): 420-436. [10] 周生玉, 胡明昊, 李冲, 丁海民, 郭乾应, 刘永长. 一种 γ'/γ'' 相强化镍基高温合金的蠕变行为[J]. 金属学报, 2025, 61(2): 226-234. [11] 鞠玉琳, 魏琪, 袁志钟, 程晓农. 低合金高强钢板贝/马复相回火过程硬度及微观组织的演变行为[J]. 金属学报, 2025, 61(10): 1531-1541. [12] 李俊杰, 李盼悦, 黄立清, 郭杰, 吴京洋, 樊凯, 王锦程. 真空自耗电弧熔炼铸锭凝固行为多尺度模拟研究进展[J]. 金属学报, 2025, 61(1): 12-28. [13] 余东, 马威龙, 王亚莉, 王锦程. Au-Pt合金凝固-固态相变微观组织演化相场法模拟[J]. 金属学报, 2025, 61(1): 109-116. [14] 曹姝婷, 赵剑, 巩桐兆, 张少华, 张健. Cu含量对K4061合金显微组织和拉伸性能的影响[J]. 金属学报, 2024, 60(9): 1179-1188. [15] 王霖, 魏晨, 王雷, 王军, 李金山. Cu-Co系难混溶合金核壳结构演化过程模拟[J]. 金属学报, 2024, 60(9): 1239-1249. Viewed Full text Abstract Cited   Shared      Discussed