高镍铌耐蚀合金945A的凝固与偏析行为  

Solidification and segregation behavior ofcorrosion resistant alloy 945A with high level of Ni and Nb

作　　者：周大地 何曲波 王方军 王东哲 孟刚 刘海定 黄海堂 ZHOU Dadi;HE Qubo;WANG Fangjun;WANG Dongzhe;MENG Gang;LIU Haiding;HUANG Haitang(Chongqing Materials Research Institute Co.,Ltd.,Chongqing 400707,China;National Engineering Research Center for Instrument Functional Materials,Chongqing 400707,China;Chongqing Key Laboratory of High-performance Corrosion-resistant Alloys,Chongqing 400707,China)

机构地区：[1]重庆材料研究院有限公司,重庆400707 [2]国家仪表功能材料工程技术研究中心,重庆400707 [3]耐腐蚀合金重庆市重点实验室,重庆400707

出　　处：《功能材料》2024年第12期12144-12150,共7页Journal of Functional Materials

基　　金：国家重点研发计划青年科学家项目(2021YFB3703000);中国机械工业集团有限公司青年科技基金项目(QNJJ-PY-2022-11);国机集团科学技术研究院有限公司青年科研基金项目(SINOMAST-QNJJ-2023-01)。

摘　　要：利用JmaPro热力学计算结合光学显微镜、扫描电镜、电子探针等方法研究了高镍铌耐蚀合金945A的析出相类型、铸态组织特征及元素偏析行为。结果表明:945A合金非平衡凝固过程中,液相中依次会析出MC型碳化物、M_(2)O_(3)型氧化物、γ基体、MN型氮化物、Laves相及η相。电渣锭铸态组织为典型的凝固组织,衬度差异明显,枝晶间大块析出相附近有针状相富集。合金元素偏析严重,Cr、Fe、Al元素偏聚于枝晶干,负偏析程度k_(Cr)>K_(Fe)>K_(Al),Nb、Mo、Ti元素在枝晶间富集,正偏析程度k_(Nb)>K_(Mo)>K_(Ti)。由于Ni、Nb、Ti在大块析出相附近偏聚,促使了针状η-Ni_(3)(Ti,Nb)的析出,而Nb、Mo、Ti在枝晶间的偏聚,导致凝固末期MgO.Al_(2)O_(3)+(Ti,Nb)N、(Nb,Ti)(C,N)+M_(23)C_(6)非金属夹杂多分布于此。By employing JmaPro thermodynamic calculations in conjunction with optical microscopy,scanning electron microscopy,and electron probe microanalysis,the types of precipitated phases,characteristics of the as-cast microstructure,and element segregation behaviors of corrosion resistant alloy 945A with high level of nickel and niobium were investigated.The results indicate that during the non-equilibrium solidification process of the 945A alloy,M_(2)O_(3)-type oxides,MC-type carbides,γmatrix,MN-type nitrides,Laves phase andηphase were sequentially precipitated in the liquid phase.The as-cast microstructure of the electroslag ingot exhibited a typical solidified structure with significant contrast differences,and there was an enrichment of needle-shaped phases near the large precipitated phases in the interdendritic regions.Severe element segregation was observed in the alloy,with Cr,Fe,and Al elements segregating towards the dendrite core,and the degree of negative segregation follows the order:k_(Cr)>K_(Fe)>K_(Al).Nb,Mo.Ti elements were enriched in the interdendritic regions,and the degree of positive segregation was k_(Nb)>K_(Mo)>K_(Ti).Due to the segregation of Ni,Nb,and Ti near the large precipitated phases,the precipitation of needle-shapedη-Ni_(3)(Ti,Nb)was facilitated.The segregation of Nb,Mo,and Ti in the interdendritic regions at the end of solidification led to the distribution of non-metallic inclusions such as MgO.Al_(2)O_(3)+(Ti,Nb)N,(Nb,Ti)(C,N)+M_(23)C_(6).

关 键 词：945A合金 凝固组织 析出相 元素偏析 

分 类 号：TF141[冶金工程—冶金物理化学] TF807