CrMnFeCoNi高熵合金中NbC析出特征及对拉伸和腐蚀性能的影响

Precipitation Characteristics of NbC in CrMnFeCoNi High-entropy Alloy and Its Effects on Tensile and Corrosion Properties

在CrMnFeCoNi高熵合金中添加了0.2%的C和0.2%的Nb,研究了微合金化对其相结构、微观组织、室温拉伸性能和腐蚀行为的影响。结果表明,CrMnFeCoNi合金经微合金化后,分别在800、900和1 000℃退火1h,除了析出面心立方结构的等轴晶基体之外,还析出NbC。随着退火温度降低,NbC的析出数量先增多后减少,900℃时析出的数量最多。NbC颗粒的析出起到了细化晶粒的作用,合金化后晶粒尺寸在上述3个温度下分别减小了41%、46%和9%;合金化还能提高基体的室温屈服强度和抗拉强度,并保持较高的伸长率,强化效果归因于NbC的析出强化和细晶强化。合金腐蚀性能的变化主要归因于NbC的析出以及晶粒尺寸的共同作用。

Effects of 0.2% addition of C and Nb(in molar fraction)on phase structure,microstructure,tensile properties at room temperature and corrosion behavior of the CrMnFeCoNi high-entropy alloy were investigated.The results show that the CrMnFeCoNi alloy with annealed at 800,900 and 1 000℃ for 1 hafter microalloying,NbC is precipitated besides of the equiaxed crystal matrix of the face-centered cubic structure.With the annealing temperature decreases,the amount of precipitation of NbC is increased firstly and then decreased,and amount of precipitation reaches the highest at 900 ℃.The precipitation of NbC particles can refine the grains.After alloying,the grain size is decreases by 41%,46% and 9% at the above three temperatures,respectively.In addition,alloying can also increase the ambient yield strength and tensile strength of the substrate with a higher elongation,which is attributed to NbC precipitation strengthening and fine grain strengthening.The change of corrosion property in this paper is mainly attributed to the effect of NbC precipitotion and grain size.