Co含量对一种新型高温合金铸态及热处理组织的影响  

Effect of Co content on the as-cast and heat-treated microstructure of a novel fourth-generation nickel-based single crystal superalloy

作　　者：刘静姝 王磊[1] 刘杨[1] 宋秀[1] 杨楠 刘世忠 李嘉荣 Liu Jingshu;Wang Lei;Liu Yang;Song Xiu;Yang Nan;Liu Shizhong;Li Jiarong(Key Laboratory for Anisotropy and Texture of Materials Ministry of Education,Northeastern University,Shenyang 110819,China;Science and Technology on Advanced High Temperature Structural Materials Laboratory,AECC Beijing Institute of Aeronautical Materials,Beijing 100095,China)

机构地区：[1]东北大学材料各向异性与织构教育部重点实验室,沈阳110819 [2]中国航发北京航空材料研究院先进高温结构材料重点实验室,北京100095

出　　处：《材料与冶金学报》2023年第4期351-360,共10页Journal of Materials and Metallurgy

基　　金：国家科技重大专项项目(2017-VI-0002-0071,J2019-VI-0020-0136);国家自然科学基金资助项目(51874090).

摘　　要：利用高温度梯度真空定向凝固方法,在保持其他元素不变的情况下,制备3种不同Co含量(质量分数,下同)的新型第四代镍基单晶高温合金,研究了Co含量对合金定向铸造凝固过程、热处理过程中偏析行为及显微组织演化的影响规律.研究结果表明:不同Co含量合金的初熔温度变化不大;随着Co含量的增加,合金的固、液相线温度升高,3种铸态合金中,质量分数为9%的Co合金(以下简称9%Co)的一次枝晶干与二次枝晶干间距最小,(γ+γ′)共晶组织含量最多;9%Co合金铸态组织偏析最为明显,Co含量的变化对Re和W等典型负偏析元素的偏析系数影响较大,而对Al和Ta等典型正偏析元素的偏析系数未见明显影响.合金经固溶处理后共晶回溶、枝晶偏析得以消除,二次时效处理后,随着Co含量的增加,γ′相平均尺寸及立方度的变化趋势均为先增大再略微减小.标准热处理后,Co含量对γ′相体积分数未见明显影响,且9%Co合金具有最佳的γ′相平均尺寸和立方度.A novel fourth-generation single crystal superalloy with three Co contents prepared by high temperature gradient vacuum directed solidification method while keeping other elements constant was used to study the effect of Co content on the solidification process of directed casting,segregation behavior during heat treatment and microstructure evolution of the alloys.The research results indicate that the initial melting temperature of the alloys with different Co contents barely changed.With the increase of Co content,the solid and liquid phase lines of the alloys were elevated,and the primary and secondary dendrite spacings in the as-cast microstructure of the alloys showed a first decreasing and then increasing trend,while the eutectic content of(γ+γ′)showed a first increasing and then decreasing trend.The alloy with 9%Co showed the most obvious segregation in the as-cast microstructure.The variation of Co content had a great effect on the segregation coefficient of typical negative segregation elements such as Re and W,but had no obvious effect on that of typical positive segregation elements such as Al and Ta.After the alloys were treated with solution treatment,eutectic back dissolution and dendrite segregation were eliminated.With the increase of Co content,the average size and cubic degree ofγ′phase of the alloys after secondary aging all showed a first increase and then a slight decrease.The alloy with 9%Co had the best average size and cubic degree ofγ′phase after standard heat treatment.No significant changes were observed in the volume fraction ofγ′phase with increasing Co content after standard heat treatment of the alloys.

关 键 词：镍基单晶高温合金 CO含量 凝固偏析 显微组织 热处理 

分 类 号：TG132.3[一般工业技术—材料科学与工程]