CoCrFeNiSn系高熵合金组织及相分析

Microstructure and phase analysis of Co-Cr-Fe-Ni-Sn high entropy alloys

以CoCrFeNi合金为基体,通过添加Sn元素和改变各元素含量,设计并制备了CoCrFeNiSn、Co_(0.5)CrFeNiSn、CoCr_(0.5)FeNiSn、CoCrFe_(0.5)NiSn、CoCrFeNi_(0.5)Sn_(5)种高熵合金。其中CoCrFeNiSn、Co_(0.5)CrFeNiSn、CoCr_(0.5)FeNiSn、CoCrFe_(0.5)NiSn合金由FCC(face-centered cubic)相(黑色相)以及六方相(灰色相)组成,并且在这几种合金均出现了共晶组织,以CoCrFe_(0.5)NiSn合金中出现的共晶组织最多。而CoCrFeNi_(0.5)Sn合金则由FCC(face-centered cubic)相(黑色相)以及四方相(灰色相)组成,没有观察到共晶组织。通过观察共晶组织体积的变化,发现Fe元素的减少有利于共晶组织的形成,Ni元素的减少不利于共晶组织的形成。EDS(Energy dispersive spectroscopy)分析结果表明Ni、Sn元素偏析在灰色相中,Co、Cr、Fe元素偏析在黑色相中。当灰色相中的Ni、Sn元素含量比在1.15~1.25范围内,有利于六方相的形成,否则灰色相倾向于形成四方相。对具有HCP结构的共晶高熵合金的设计和开发具有一定的借鉴和指导意义。

In this paper,five high-entropy alloys,CoCrFeNiSn,Co_(0.5)CrFeNiSn,CoCr_(0.5)FeNiSn,CoCrFe_(0.5)NiSn and CoCrFeNi_(0.5)Sn,were designed and prepared by adding Sn element and changing the content of each element based on CoCrFeNi alloy.Among them,CoCrFeNiSn,Co_(0.5)CrFeNiSn,CoCr_(0.5)FeNiSn and CoCrFe_(0.5)NiSn alloys are composed of FCC phase(black phase)and hexagonal phase(gray phase),and eutectic structure appears in these alloys,especially for CoCrFe_(0.5)NiSn alloy.The CoCrFeNi_(0.5)Sn alloy is composed of FCC(face-centered cubic)phase(black phase)and tetragonal phase(gray phase),and no eutectic structure is observed.By observing the change of eutectic structure volume,it is found that the reduction of Fe element is beneficial to the formation of eutectic structure,and the reduction of Ni element is not conducive.The results of EDS(energy dispersive spectroscopy)analysis showed that Ni and Sn are segregated in the gray phase,and Co,Cr and Fe are segregated in the black phase.In addition,when the content ratio of Ni and Sn in the gray phase is in the range of 1.15 to 1.25,it is favorable for the formation of the hexagonal phase,otherwise the gray phase tends to form the tetragonal phase.This paper has certain reference and guiding significance for the design and development of eutectic high-entropy alloys with HCP structure.