FeCoNiCrCu高熵合金涂层对复合铸造Al/Mg双金属组织和性能的影响

Effect of FeCoNiCrCu High Entropy Alloy Coating on Microstructure and Properties of Al/Mg Bimetal by Compound Casting

目的研究不同厚度的FeCoNiCrCu高熵合金涂层对Al/Mg双金属组织和力学性能的影响。方法通过超音速火焰喷涂工艺在A356嵌体表面喷涂不同厚度的FeCoNiCrCu高熵合金涂层,采用消失模复合铸造工艺制备Al/Mg双金属,利用扫描电镜、EDS能谱及XRD衍射仪、维氏硬度测试仪和万能试验机对Al/Mg双金属界面微观组织和力学性能进行测试和分析。结果未喷涂高熵合金涂层的Al/Mg双金属界面由共晶层和金属间化合物层组成,断裂位置主要位于金属间化合物层,裂纹从Al_(3)Mg_(2)扩展至共晶层结束,具有典型的脆性断裂特征,剪切强度仅为30.37MPa。当高熵合金涂层厚度为5μm时,Al/Mg双金属形成了Al_(3)Mg_(2)+Mg_(2)Si/AlxFeCoNiCrCu+FeCoNiCrCu+Al-Mg-Co-Ni混合相/δ-Mg+Al_(12)Mg_(17)共晶组织的复杂界面,断裂发生在高熵合金层与δ-Mg+Al_(12)Mg_(17)共晶组织的交界处,断裂面产生了一定程度的塑性变形,剪切强度为48.46MPa,相对于无涂层的Al/Mg双金属提高了59.56%。当高熵合金涂层厚度为20μm时,铝侧生成了AlxFeCoNiCrCu高熵合金,镁侧则只生成了少量Mg-Ni-Cu混合相,断裂发生在高熵合金涂层与镁基体交界处,剪切强度为39.69 MPa。结论高熵合金涂层可以有效阻碍Al、Mg元素之间的扩散,从而显著抑制或完全阻止Al-Mg脆性金属间化合物的产生,大幅度降低界面层厚度。金属间化合物的减少和混合相对裂纹扩展的阻碍作用显著提高了Al/Mg双金属界面的剪切强度。

The work aims to study the effect of FeCoNiCrCu high entropy alloy(HEA)coating with different thicknesses microstructure and mechanical properties of Al/Mg bimetal.FeCoNiCrCu HEA coatings with different thicknesses were sprayed on the surface of A356 inlay through high velocity oxygen fuel spraying,and the Al/Mg bimetal was prepared by lost foam composite casting.Scanning electron microscopy,EDS spectroscopy,XRD diffraction,Vickers and universal testing machine were used to test and analyze the microstructure and mechanical properties of the Al/Mg bimetal.The Al/Mg bimetal without a HEA coating was composed of an eutectic layer and an intermetallic compound layer.The fracture location was located in the intermetallic compound layer.The crack extended from Al_(3)Mg_(2) to the eutectic layer,having typical brittle fracture characteris-tics.The shear strength was only 30.37 MPa.When the HEA coating thickness was 5μm,the Al/Mg bimetal formed a complex interface of Al_(3)Mg_(2)+Mg_(2)Si/AlxFeCoNiCrCu+FeCoNiCrCu+Al-Mg-Co-Ni mixed phases/δ-Mg+Al_(12)Mg_(17) eutectic structure,and the fracture occurred between the HEA and theδ-Mg+Al_(12)Mg_(17) eutectic structure.The fracture surface produced a certain degree of plastic deformation.The shear strength was 48.46 MPa,increased by 59.56%compared with that without a coating.When the thickness of the HEA coating was 20μm,AlxFeCoNiCrCu HEA was formed on the Al side,and only a small amount of Mg-Ni-Cu mixed phases were formed on the Mg side.Fracture occurred between the HEA coating and the Mg matrix.The shear strength was 39.69 MPa.The HEA coating can effectively hinder the diffusion between Al and Mg elements,thereby sig-nificantly inhibiting or completely preventing the generation of Al-Mg brittle intermetallic compounds and greatly reducing the thickness of the interface layer.The reduction of intermetallic compounds and the hindering effect of mixed phases significantly improve the shear strength of the Al/Mg bimetal.