基于超声强化改性研磨时长的AlCoCrFeNi_(2.1)共晶高熵合金组织和力学性能影响研究

Study on the Influence of Ultrasonic Strengthening and Modified Grinding Time on the Structure and Mechanical Properties of AlCoCrFeNi_(2.1) Eutectic High Entropy Alloy

为提高室温下AlCoCrFeNi_(2.1)共晶高熵合金(EHEAs)的极限拉伸强度和延展性,通过光镜观察截面显微组织、维氏显微硬度计测量截面显微硬度、白光干涉仪分析表面三维形貌、拉伸试验机进行室温单轴拉伸试验,并绘制工程应力-应变曲线,利用扫描电镜分析断口形貌等仪器研究在不同时长(3、6、9 min)超声强化改性研磨(USG)处理下AlCoCrFeNi_(2.1)EHEAs显微组织和性能的变化规律。结果表明:与母材相比,超声强化改性研磨使AlCoCrFeNi_(2.1)EHEAs由外表至芯部形成厚度最高约120μm的强化层,表面三维形貌先增加到1.987μm后减少至1.490μm,表层显微硬度最高提升了30.40%,极限拉伸强度最高提升了25%,延展性最高提升至15.04%,且母材表层断口形貌特征为韧性断裂,经超声强化改性研磨处理后样件断口形貌特征均为韧-脆混合型断裂。可得结论:超声强化改性研磨可以有效提高AlCoCrFeNi_(2.1)共晶高熵合金的表层硬度和晶粒细化的强化层,从而协同提高其极限拉伸强度和延展性。

To improve the ultimate tensile strength and ductility of AlCoCrFeNi_(2.1)eutectic high entropy alloys (EHEAs) at room temperature,microstructure of the cross-section is observed with light microscope,microhardness of the cross-section is measured with a Vickers microhardness tester,surface three-dimensional morphology is analyzed with a white light interferometer,and room temperature uniaxial tensile testing is conducted on a tensile testing machine to draw engineering stress-strain curves.Scanning electron microscopy is used to analyze the fracture morphology and other instruments to study the changes in microstructure and properties of AlCoCrFeNi_(2.1)EHEAs under the treatment of ultrasonic strengthening and modified grinding (USG) at different durations (3,6,9 min).Results show that,compared with the base material,AlCoCrFeNi_(2.1)EHEAs USG treatment has a maximum thickness of about 120μm from the outer surface to the core;the surface three-dimensional morphology firstly increases to 1.987μm then reduces to 1.490μm;the surface microhardness increased by a maximum of30.40%,the ultimate tensile strength increased by a maximum of 25%,and the ductility increased by a maximum of 15.04%;the surface fracture morphology of the base material is characterized by ductile fracture;after USG,the fracture morphology of the sample is characterized by a mixed ductile brittle fracture.Conclusion can be drawn that USG can effectively improve the surface hardness and grain refinement of AlCoCrFeNi_(2.1)EHEAs,thereby synergistically enhancing its ultimate tensile strength and ductility.