FeCoNiCuAl系多主元高熵合金组织与性能的研究

发布时间：2018-06-30 21:10

  本文选题：多主元高熵合金 + 相组成　； 参考：《南昌大学》2017年硕士论文

【摘要】：相比传统合金,多主元高熵合金不仅由简单的相组成,而且还具有高硬度、高强度、良好抗磨性及耐腐蚀性等优异的性能,因此多主元高熵合金逐渐成为新型金属材料领域中备受关注的研究热点。本文以FeCoNiCuAl系多主元高熵合金为研究对象,采用了X射线衍射仪(XRD)、金相显微镜(OM)、扫描电子显微镜(SEM)、能谱仪(EDS)、显微硬度测试、压缩性能测试等实验分析方法,研究了Al和Cu含量对FeCoNiCuAl系多主元高熵合金组织结构(相结构及组成、微观组织、元素分布)和性能(硬度、压缩性)的影响。同时,本文还研究了退火温度对冷轧态FeCoNiCuAl_(0.5)高熵合金组织结构和硬度的影响。结果表明:(1)在FeCoNiCuAl_x(x=0.5、1.0、1.5、2.0)多主元高熵合金中,四种合金都由简单的fcc结构和bcc结构相组成,但随着Al含量的增加,bcc相体积分数增多,fcc相体积分数减少,当x=2.0时,合金主要为bcc相,只有少量的fcc相。四种合金铸态下均为典型的树枝晶组织,枝晶间存在明显的Cu富集,并且随着Al含量的增加加剧了Cu元素的偏析程度。同时,FeCoNiCuAl_x合金的显微硬度和屈服强度也随Al含量的增加而增大,FeCoNiCuAl2.0合金的显微硬度和屈服强度达到了最大值,分别为568 HV和1435 MPa,但是该合金体系的塑性却随Al含量的增加而呈降低的趋势。(2)在FeCoNiAlCu_x(x=0.5、0.8、1.0、1.5)多主元高熵合金中,四种合金也均由fcc结构相和bcc结构相组成,但随着Cu含量的增加,fcc相体积分数增多,而bcc相体积分数减少;四种合金铸态下均为典型的树枝晶组织,枝晶间存在明显的Cu富集,并且随着Cu含量的增加而加剧了Cu元素在枝晶间的富集,但在枝晶内没有变化。同时,FeCoNiAlCu_x合金的显微硬度和屈服强度均随Cu含量的增加而降低,FeCoNiAlCu0.5合金的显微硬度最高,达到569 HV,FeCoNiAlCu0.8合金的屈服强度最大,为1256 MPa,但是该合金体系的塑性却是随着Cu含量的增加而显著提高,FeCoNiAlCu1.5合金的塑性最好,其压缩应变高达36.1%。此外,Cu元素含量对该合金体系的断裂类型也有明显的影响,从合金FeCoNiAlCu0.5的解理断裂演变到合金FeCoNiAlCu1.5的塑性断裂。(3)对冷轧态FeCoNiCuAl_(0.5)多主元高熵合金进行不同温度退火处理。当退火温度为700-900℃时,合金的显微组织形貌均表现为典型的树枝晶组织,枝晶由fcc相构成,枝晶间由bcc相构成。但当退火温度升高到1000℃时,合金中只含有fcc相,同时促进了元素的均匀分布,消除了部分枝晶偏析。此外,合金的显微硬度随退火温度升高而呈先增大后减小趋势,在700℃时,合金显微硬度达到最大值为418 HV,且经过退火处理的合金的显微硬度均高于冷轧态的显微硬度。
[Abstract]:Compared with conventional alloys, multi-principal element high-entropy alloys not only consist of simple phases, but also have excellent properties such as high hardness, high strength, good wear resistance and corrosion resistance. Therefore, multi-principal element high-entropy alloys have gradually become the focus of research in the field of new metal materials. In this paper, FeCoNiCuAl multi-principal component high entropy alloy is studied. The methods of X-ray diffraction (XRD), metallographic microscope (OM), scanning electron microscope (SEM), energy spectrometer (EDS), microhardness test, compression property test, etc. The effects of Al and Cu contents on the microstructure (phase structure and composition, microstructure, element distribution) and properties (hardness, compressibility) of FeCoNiCuAl multiprincipal element high entropy alloy were studied. At the same time, the effect of annealing temperature on the microstructure and hardness of cold-rolled FeCoNiCuAl0.5 high entropy alloy was studied. The results show that: (1) in FeCoNiCuAlx multiprincipal element high entropy alloy, the four alloys are composed of simple fcc structure and bcc structure phase, but with the increase of Al content, the volume fraction of FCC phase decreases. When x2.0, the alloy is mainly bcc phase. There is only a small amount of fcc phase. The dendritic structure of the four alloys is typical in the as-cast state. There is obvious Cu enrichment between the dendrites, and the segregation degree of Cu is aggravated with the increase of Al content. At the same time, the microhardness and yield strength of FeCoNiCuAlx alloy increased with the increase of Al content, and the microhardness and yield strength of FeCoNiCuAl2.0 alloy reached the maximum value. The plasticity of the alloy system decreased with the increase of Al content. (2) in FeCoNiAlCux (0.50.80.81.50) multiprincipal element high entropy alloy, the four alloys also consist of fcc structure phase and bcc structure phase. However, with the increase of Cu content, the volume fraction of FCC phase increases, while the volume fraction of bcc phase decreases. With the increase of Cu content, the enrichment of Cu elements between dendrites is intensified, but there is no change in the dendrite. At the same time, the microhardness and yield strength of FeCoNiAlCux alloy decreased with the increase of Cu content, and the highest microhardness of FeCoNiAlCu0.5 alloy reached the highest yield strength of 569 HVN FeCoNiAlCu0.8 alloy. The ductility of the alloy system is 1256 MPA, but the plasticity of FeCoNiAlCu1.5 alloy is the best with the increase of Cu content, and the compressive strain of the alloy is as high as 36.1. In addition, the content of Cu also has a significant effect on the fracture type of the alloy system, from cleavage fracture of FeCoNiAlCu0.5 to plastic fracture of FeCoNiAlCu1.5. (3) annealing of cold-rolled FeCoNiCuAl0.5 multi-principal element high entropy alloy at different temperatures. When annealing temperature is 700-900 鈩，

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