单晶高温合金DD419籽晶引晶过程中杂晶形成机制  

Stray Grain Formation Mechanism During Seeding Process of Single Crystal Superalloy DD419

作　　者：邓阳丕 马德新 赵运兴 徐维台 徐福泽 李侣 Deng Yangpi;Ma Dexin;Zhao Yunxing;Xu Weitai;Xu Fuze;Li Lv(Shenzhen Wedge Central South Research Institute Co.,Ltd,Shenzhen 518045,China;Powder Metallurgy Research Institute,Central South University,Changsha 410083,China)

机构地区：[1]深圳市万泽中南研究院有限公司,广东深圳518045 [2]中南大学粉末冶金研究院,湖南长沙410083

出　　处：《稀有金属材料与工程》2024年第7期2042-2048,共7页Rare Metal Materials and Engineering

基　　金：广东省引进创新创业团队项目(607264877417);深圳市科技计划(JSGG20220831092800001)。

摘　　要：采用不同程度加工处理过的籽晶进行了高温合金DD419单晶铸件的制备实验,对宏观腐蚀后的铸件籽晶进行表面观察,并检测了相应部位的金相组织和晶体取向,对杂晶的起源进行了研究分析。结果发现,轻度加工的籽晶表面仅出现轻微再结晶,未对引晶造成影响,而中度和重度加工的籽晶有不同程度的再结晶。这些籽晶表面的再结晶产生于浇注前的预热和保温阶段,与铸件经标准固溶热处理后产生的再结晶形貌非常相似。在预热与浇注过程中,这些再结晶得到部分熔化,在随后的凝固过程中,回熔界面附近未熔的残余再结晶晶粒外延生长,从而形成杂晶缺陷。本工作证明了籽晶回熔区内杂晶的起源是籽晶表面的再结晶,而不是通常认为的液相中新晶粒形核。The single crystal(SC) castings of superalloy DD419 were prepared using seeds deformed in different degrees.The grain structure on the etched seed surface and on the longitudinal sections was examined,combined with the measurement of metallographic structure and crystal orientation of the corresponding parts,in order to identify the origin of the stray grains.The results show that on the surface of the slightly-deformed seeds,only slightly recrystallized grains are detected,which have no influence on the seeding process of the superalloy castings.In the moderately and severely deformed seeds,however,grains with different recrystallization degrees are observed.It is deduced that the recrystallization on the surface of deformed seeds occurs during preheating and holding stage before pouring,which is very similar to the recrystallization structure formed during the conventional solution heat treatment.These recrystallized grains are partially melted in preheating and pouring stage.In the subsequent solidification process,stray grains grow epitaxially from the unmelted residual recrystallized grains near the remelting interface.The experimental results show that the origin of the stray grains during seeding process is the recrystallization in the seed surface layer,instead of the nucleation of the new grains in the liquid phase.

关 键 词：单晶高温合金 籽晶 再结晶 杂晶 

分 类 号：TG146.15[一般工业技术—材料科学与工程]