杨伟,夏卫,徐志锋,蔡长春,胡啸.近平衡与亚快速凝固条件下K424高温合金组织演化规律研究[J].稀有金属材料与工程,2016,45(1):117~121.[yangwei,Xia Wei,Xu Zhifeng,Cai Changcun,Hu Xiao.Microstructure Evolution of K424 Superalloy during Near-equilibrium and Sub-rapid Solidification Processes[J].Rare Metal Materials and Engineering,2016,45(1):117~121.]
近平衡与亚快速凝固条件下K424高温合金组织演化规律研究
投稿时间:2014-02-20  修订日期:2014-04-20
中文关键词:  镍基高温合金  冷却速率  晶粒细化  相结构
基金项目:国家自然科学基金项目(面上项目,重点项目,重大项目)
中文摘要:
      采用差示扫描量热仪与铜模喷铸技术,研究了较宽冷速(0.17~100 K/s)范围内K424镍基高温合金的近平衡与亚快速凝固行为。利用光学显微镜、扫描电镜及能谱分析仪对不同冷速作用下K424合金γ基体相、γ′沉淀相、MC碳化物及共晶组织进行了表征,并对平均二次枝晶间距进行了定量分析。结果表明:冷速的提高有效细化了初生γ相,二次枝晶间距由0.17 K/s时的84 μm显著下降到100 K/s时的5 μm, 同时导致γ′沉淀相的析出时间缩短,平均晶粒尺寸下降。亚快速凝固条件下所形成的过饱和固溶体在后续加热过程中发生沉淀相析出。枝晶组织的细化与溶质截留的发生,降低了凝固过程中成分偏析,有利于γ+γ′共晶相及碳化物尺寸的下降。
Microstructure Evolution of K424 Superalloy during Near-equilibrium and Sub-rapid Solidification Processes
英文关键词:Nickel-base superalloy  Cooling rate  Grain refinement  Phase structure
英文摘要:
      Adopting differential scanning calorimetry and copper-mould spray-casting methods, the near-equilibrium and sub-rapid solidification of K424 superalloy were fabricated with a wide range of cooling rate between 0.17 K/s and 100 K/s. Using OM, SEM and EDS, the evolutions of primary γ phase, precipitated γ′ phase, MC carbides and eutectic microstructure were described as a function of cooling rate. It is shown that γ phase is refined with increasing cooling rate, where the secondary dendrite spacing decreases from 84 μm for 0.17 K/s to that of 5 μm for 100 K/s. Moreover, the average size of precipitated γ′ phase decreases because of the shortened time for transformation. Precipitation process occurs once again as for heating the formed supersaturated solid solution during sub-rapid solidification. Both the refinement of γ phase and solute trapping decrease the extent of solute segregation, which leads to the reduction of the sizes of γ+γ′ eutectic and carbides.
作者单位E-mail
杨伟 南昌航空大学轻合金加工科学与技术国防重点学科实验室 nchkyw@163.com 
夏卫 南昌航空大学 轻合金加工科学与技术国防重点学科实验室  
徐志锋 南昌航空大学 轻合金加工科学与技术国防重点学科实验室  
蔡长春 南昌航空大学 轻合金加工科学与技术国防重点学科实验室  
胡啸 中航工业南方航空工业(集团)有限公司  
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