铸造/烧结钴铬镍合金组织演变规律的对比研究  

Comparation in microstructure evolutions between casted and sintered Co-Cr-Ni alloys

作　　者：李光宇 石增敏 邓李辰贵 王珂胜 朱哲 戴雷 赵光伟 LI Guangyu;SHI Zengmin;DENGLI Chengui;WANG Kesheng;ZHU Zhe;DAI Lei;ZHAO Guangwei(Hubei Key Laboratory of Hydroelectric Machinery Design&Maintenance,China Three Gorges University,Yichang 443002,Hubei,China)

机构地区：[1]三峡大学水电机械设备设计与维护湖北省重点实验室,湖北宜昌443002

出　　处：《材料工程》2024年第5期127-137,共11页Journal of Materials Engineering

基　　金：水电机械设备设计与维护湖北省重点实验室开放基金(2020KJX01)。

摘　　要：采用亚快速凝固和真空烧结两种工艺方法制备了钴铬镍合金,详细研究了工艺方法及Cr,Ni含量对合金组织演变规律的影响。结果表明,亚快速凝固工艺所获得的钴铬镍合金组织组成不受成分变化的影响,凝固组织为γ-fcc+ε-hcp两相组织的胞状枝晶,枝晶干为γ-fcc相,枝晶间为ε-hcp相,二次枝晶间距随结晶速率增大而减小,主要溶质元素Cr,Ni在两相间产生偏析,Cr元素富集在枝晶间,Ni元素在枝晶干富集。真空烧结工艺所制备钴铬镍合金组织构成由成分组成决定,低镍含量合金烧结体为单相ε-hcp组织,晶粒随烧结温度的升高呈现急剧粗化特征;高镍含量合金烧结体为γ-fcc+ε-hcp双相组织,晶粒细小且γ-fcc相呈现明显的孪晶和层错结构。烧结合金较铸造合金呈现明显的塑性增长,位错是烧结低镍ε-hcp单相合金性能提升的主要因素,孪晶和层错则是高镍γ-fcc+ε-hcp两相合金组织性能提升的主要因素。Cobalt-chromium-nickel(Co-Cr-Ni) alloys were prepared by two techniques of the sub-rapid solidification(SRS) and vacuum sintering(VS). The effects of the preparation processing and the content of Cr, Ni on the microstructure evolution were investigated in detail. Results show samples under SRS present a typical dual-phase dendrite microstructure of the face centered cubic(γ-fcc) crystal and the hexagonal closest packing(ε-hcp) crystal, which is independent of the raw material composition. The γ-fcc phase forms in dendrite arms, while the ε-hcp phase forms in inter-dendrites. With the increase of the solidification rate, the secondary dendrite spacing decreases. The main solute elements Cr and Ni take segregation between the two phases of γ-fcc and ε-hcp. Cr concentrates in inter-dendrites, and Ni exists in dendrite arms. The microstructure of cobalt chromium nickel alloy prepared by VS is determined by its composition, and the sintered body of low nickel content alloy is single-phase ε-hcp structure, the grains exhibit a sharp coarsening characteristic with the increase of sintering temperature. The sintered body of high nickel content alloy is γ-fcc+ ε-hcp dual phase structure, the grains are small and γ-fcc phase exhibits obvious twinning and stacking fault structures. Compared with the casted alloy, the sintered alloy exhibits a marked improvement in the uniform plastic elongation. The dislocation defect is the prime microstructural unit that promotes the improvement in the mechanical property of the sintered alloy with the single-phase structure of ε-hcp, while the defects of the crystal twins and stacking faults are considered as the key factors determining both the strength and toughness for those with the dual-phase structure of ε-hcp and γ-fcc.

关 键 词：钴铬镍合金 粉末冶金 真空烧结 亚快速凝固 组织演变 

分 类 号：TG249[金属学及工艺—铸造] TG125