CoFeNi系高熵合金显微组织刻蚀方法研究

Studies on Microstructure Etching Methods for CoFeNi High-Entropy Alloys

摘要: 采用机械合金法 + 放电等离子热压烧结技术制备CoFeNi系高熵合金。使用三种不同浓度的无水乙醇稀释的王水作为刻蚀剂，通过调控刻蚀时间，研究其对CoFeNi系高熵合金显微组织的影响。采用X射线衍射分析仪和扫描电子显微镜分析了经不同刻蚀方法的CoFeNi系高熵合金的物相显微组织形貌。结果表明：CoFeNi、CoFeNiAl_0.5、CoFeNiAl_0.5Cr_0.5和CoFeNiAl_0.5Cr_0.5Si_0.5，合金相组成从FCC相转变为FCC + BCC相，且BCC相的含量逐渐增加，直至成为主相。以获取最清晰的高熵合金显微组织为标准，CoFeNi合金的最佳刻蚀工艺为Etchant#3溶液中刻蚀5 s~10 s；CoFeNiAl_0.5合金为Etchant#2溶液中刻蚀10 s~20 s；CoFeNiAl_0.5Cr_0.5合金为Etchant#2溶液中刻蚀10 s~20 s；CoFeNiAl_0.5Cr_0.5Si_0.5合金为Etchant#1溶液中刻蚀10 s~20 s。

Abstract: CoFeNi high-entropy alloys (heas) were prepared using a mechanical alloying method combined with discharge plasma hot-press sintering technology. Three different concentrations of aqua regia diluted with anhydrous ethanol were employed as etching agents. The effects of etching time on the microstructure of the CoFeNi heas were investigated. The microstructural morphology of the CoFeNi heas treated with different etching methods was analyzed using X-ray diffraction and scanning electron microscopy. Results indicate that for CoFeNi, CoFeNiAl_0.5, CoFeNiAl_0.5Cr_0.5, and CoFeNiAl_0.5Cr_0.5Si_0.5 alloys, the phase composition transitions from FCC to FCC + BCC, with the BCC phase gradually increasing in content until it becomes the dominant phase. To obtain the clearest microstructure of the high-entropy alloys, the optimal etching conditions were determined as follows: CoFeNi alloy requires 5~10 s etching in Etchant#3 solution; CoFeNiAl_0.5 alloy requires 10~20 s etching in Etchant#2 solution; CoFeNiAl_0.5Cr_0.5 requires 10~20 s etching in Etchant#2 solution; CoFeNiAl_0.5Cr_0.5Si_0.5 alloy requires 10~20 s etching in Etchant#1 solution.