一种新型Ni-Cr-Co基变形高温合金的均匀化工艺  

Homogenization of a New-Type Ni-Cr-Co Based Wrought Superalloy

作　　者：丁雨田[1,2] 闫康 马元俊 高钰璧 陈建军 王兴茂 Ding Yutian;Yan Kang;Ma Yuanjun;Gao Yubi;Chen Jianjun;Wang Xingmao(School of Material Science and Engineering,Lanzhou University of Technology,Lanzhou 730050,China;State Key Laboratory of Advanced Processing and Recycling of Non-Ferrous Metals,Lanzhou University of Technology,Lanzhou730050,China)

机构地区：[1]兰州理工大学材料科学与工程学院,甘肃兰州730050 [2]兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室,甘肃兰州730050

出　　处：《稀有金属》2023年第10期1342-1351,共10页Chinese Journal of Rare Metals

基　　金：国家重点研发计划项目(2017YFA0700703);国家自然科学基金项目(51661019);甘肃省科技重大专项项目(145RTSA004)资助。

摘　　要：利用光学显微镜(OM)、扫描电子显微镜(SEM)、电子探针(EPMA)、能谱仪(EDS)和JMatPro热力学软件对采用真空感应熔炼(VIM)和电渣重熔(ESR)双联工艺冶炼得到的Ni-Cr-Co基变形高温合金铸锭进行微观组织、析出相和元素偏析研究,并且运用JMatPro计算评价不同的均匀化处理工艺,结合均匀化后的组织分析、元素偏析消除程度,最终确定了最佳的均匀化制度。结果表明,铸锭存在明显的树枝晶和元素偏析,各元素的偏析程度大小为:Ti>W>Al>Co>Cr,其中Ti元素偏析最严重,W元素次之,偏析系数(K)分别为2.37和0.62;Ti元素在枝晶间大量富集促进针状η相的形成,并且枝晶间处的γ′相尺寸明显大于枝晶干处,其大小分别为96和55 nm。JMatPro理论计算表明,在1180℃保温24 h后元素基本已经扩散均匀;在均匀化退火过程中,随保温时间的延长,树枝晶和元素偏析逐渐被消除,η相回熔,并且合金塑性大幅度提高,其延伸率达到40%左右,约为铸态合金的两倍;实验结果证明JMatPro能够很好地预测退火处理消除枝晶偏析的程度,在均匀化处理24 h之后元素的偏析已经大部分被消除,KTi和KW分别为1.11和0.87;将保温时间延长至40 h后,Ti和W元素基本扩散均匀,KTi=1.03,KW=0.93,合金晶粒尺寸均一且无异常长大。The development of highly alloyed tendency of nickel-based wrought superalloys is prone to bring disadvantages such as poor microstructure stability and large deformation resistance while improving the strength of the alloy.Therefore,a new-type Ni-Cr-Co based wrought superalloy with low alloying and low stacking fault energy was designed based on the concept of plainification,which was used as a synergistic strengthening model alloy for studying plainification on the basis of structure of"phase and nanotwin".Consequently,the combination of strength and plasticity of the alloy could be achieved instead of alloying method.The alloy contained arelatively high content of Tielement that is easy to segregate.The m phases could be precipitated when Ti is enriched seriously during solidification,which would accelerate the formation and propagation of cracks and greatly reduce the service life,and indirectly weaken the strengthening effect of alloying elements.Therefore,the ingot might be homogenized to eliminate dendrite segregation and improve the plastic processing ability of the alloy,which was prepared for controlling high density twins of the new-type Ni-Cr-Co based wrought superalloy.This work was combined JMatPro simulation calculation with systematic experiments to explore the appropriate homogenization treatment.The microstructure and microsegregation of Ni-Cr-Co based wrought superalloy ingot prepared by vacuum-induction-melting(VIM)and electroslag-remelting(ESR)were studied by optical microscopy(OM),scanning electron microscopy(SEM),electron probe micro analysis(EPMA),energy-dispersive X-ray spectroscopy(EDS)and JMatPro thermodynamic software.The segregation degree of each element was characterized by the segregation coefficient(K).The homogenization module of JMatPro was used to predict the elimination degree of element segregation after homogenization at 1180°C for different time.Based on the calculation results,the homogenization treatments were carried out at 1180℃ for different time with the interval o

关 键 词：高温合金 偏析 均匀化 微观组织 

分 类 号：TG132.32[一般工业技术—材料科学与工程]