三种单晶高温合金的形核过冷度测量及相应凝固组织研究  

Nucleation Undercooling Measurement and Corresponding Solidification Structure Investigation of Three Single Crystal Superalloys

作　　者：徐维台 马德新 赵运兴 皮立波 孙中源 Xu Weitai;Ma Dexin;Zhao Yunxing;Pi Libo;Sun Zhongyuan(l.Shenzhen Wedge Central South Research Institute Co.,518045 China;Powder Metallurgy Research Institute,ral 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》2022年第7期2637-2644,共8页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(91860103,92060104)。

摘　　要：采用悬垂小球法在工业条件下对DD5、DD6以及WZ303种镍基高温合金进行熔体过冷实验,测量了3种合金在加热和冷却过程中的液相线温度T和临界形核温度T,测得这3种合金的临界形核过冷度ΔT=T-T分别是33、36和42℃。合金DD5和DD6试样凝固时由于过冷度相对较小,形成细枝状单晶组织。合金WZ30的临界形核过冷度相对较大,试样凝固时主要形成由晶向一致的树枝状单晶基体框架和晶向散乱的碎粒状杂晶组成的混合体组织,其中大部分碎粒状杂晶的形态和尺寸特征像是从液体中直接形核长大的等轴晶粒团簇,而不是来源于枝晶臂的熔断。The undercooling behavior of three single crystal(SC)superalloys DD5, DD6 and WZ30 was investigated under the industrial process condition by the pendant pellet method. During isothermal heating and cooling processes, the liquidus temperature Tand the critical nucleation temperature Tof the alloys were measured. As the average critical nucleation undercooling ΔT=T-Tis determined to be 33, 36 and 42 ℃ for the three alloys. In the samples of alloy DD5 and DD6 with relatively low ΔTN value, very fine dendritic microstructure forms during isothermal cooling processes. In the sample of alloy WZ30 with relatively high nucleation undercooling, the solidification structure becomes a mixture of SC dendrite frame and grain clusters with random orientations. It appears that, the most random oriented grains are equiaxed crystal formed directly from the interdendritic residual melt, instead of dendrite arm fragment owing to remelting.

关 键 词：单晶高温合金 过冷能力 临界形核过冷度 凝固组织 

分 类 号：TG132.33[一般工业技术—材料科学与工程]