摘要
采用激光选区熔化(SLM)增材制造技术制备了一种新型FeCoNi中熵合金,通过扫描电子显微镜(SEM)、X射线衍射(XRD)、电子背散射衍射技术(EBSD)和透射电子显微镜(TEM),研究热处理对合金微观组织与硬度的影响规律,揭示SLM中熵合金的强化机理。结果表明,沉积态合金致密度为99.9%以上,平均晶粒尺寸为2.2μm,组织为单相BCC结构,硬度为32.6 HRC。经过470℃热处理后,在晶界和晶内析出双尺寸的Ni3Fe金属间化合物,硬度大幅增加到47.6 HRC。随着热处理温度的进一步增加,合金中生成了粗大的FCC软化相,且FCC相的含量随热处理温度的升高逐渐增多,700℃热处理后FCC相含量达到36%,合金的硬度降低至36.3 HRC。因此,热处理过程中析出富Ni金属间纳米相是提升FeCoNi中熵合金性能的主要原因之一。
A novel FeCoNi medium entropy alloy was fabricated by selective laser melting(SLM)additive manufacturing technology.Effect of heat treatment on microstructure and hardness of the alloy was studied by scanning electron microscopy(SEM),X-ray diffraction(XRD),electron backscatter diffraction(EBSD)and transmission electron microscopy(TEM),and strengthening mechanism of SLM medium entropy alloy was revealed.The results showed that relative density of deposited alloy was above 99.9%,and average grain size was 2.2μm.Microstructure was single-phase BCC structure,and hardness was 32.6 HRC.After heat treatment at 470℃,dual-size Ni3Fe intermetallic compounds precipitated at grain boundary and in grains,and hardness increased significantly to 47.6 HRC.With the further increase of heat treatment temperature,coarse FCC softening phase was formed in the alloy,and content of FCC phase gradually increased with the increase of heat treatment temperature.Content of FCC phase reached 36% after 700℃ heat treatment,and hardness of the alloy decreased to 36.3 HRC.Therefore,precipitation of rich-Ni intermetallic compound in BCC matrix during heat treatment was one of the main reasons for improving properties of FeCoNi medium entropy alloy.
作者
夏忠虎
张友昭
任延杰
李相伟
张书彦
Xia Zhonghu;Zhang Youzhao;Ren Yanjie;Li Xiangwei;Zhang Shuyan(Changsha University of Science&Technology,Changsha 410014,China;Centre of Excellence for Advanced Materials,Dongguan 523808,Guangdong,China)
出处
《焊接》
2024年第2期36-42,共7页
Welding & Joining
基金
广东省基础与应用基础研究重大项目(2020B0301030001)。
关键词
中熵合金
激光选区熔化
热处理
微观组织
洛氏硬度
medium entropy alloy
selective laser melting
heat treatment
microstructure
Rockwell hardness
