Microstrucyure Of Laser Cladding Cu Hf Al Amorphous Composite Coating Research On Structutre And Mechanical Performance

Copper metal materials have excellent thermal conductivity and conductivity,but their hardness and strength are low,so they are difficult to be used in structural components.At the same time,their poor tribological properties can not meet the working conditions of high strength and wear resistance,which further hinders the development and application of copper metal materials.In this paper,a multifunctional amorphous composite cladding layer is prepared on the surface of copper by using advanced laser cladding technology and the mechanical properties of amorphous alloy with high strength and high hardness,so as to improve the surface properties of copper and expand the application range of copper.Taking the ternary Cu-Hf-Al amorphous system as the research object,,two kinds of five element alloy powders Cu-Hf-Al-V-Nb and Cu-Hf-Al-Mo-Ta were prepared by vacuum arc melting.The amorphous composite cladding layer was prepared on the copper substrate by the preset laser cladding process,and the excitation process parameters were optimized by the orthogonal method.The effects of heat input on the surface morphology and dilution ratio of two different component cladding layers are discussed.At the same time,the amorphous content,interface bonding and microstructure of the two component cladding layers are also analyzed through different heat input.With the decrease of heat input,the amorphous content on the surface of Cu₅₀Hf₃₆Al₇V₄Nb₃and Cu₄₇Hf₄₂Al₆Mo₄Ta₁cladding layers increases,and it is found that the maximum amorphous content is 56.46%and 81.83%respectively.Under different heat input conditions,the copper matrix also realizes good metallurgical combination with each cladding layer.The two cladding layers have multi-scale microstructure of ultrafine and nanocrystalline,but the microstructure is also very different.The epitaxial growth of the cladding layer prepared by Cu₅₀Hf₃₆Al₇V₄Nb₃alloy powder is interrupted by the massive,rod-shaped and lamellar structures in the cladding layer.The cladding layer formed by the latter is interrupted by equiaxed crystal after small-scale epitaxial growth,and the microstructure has gradient transformation with the change of Cu content.The properties of two different types of amorphous composite cladding layers were studied.It was measured that when the heat input was the smallest,the surface microhardness of the two cladding layers was the highest,which was 809HV_0.5and839HV_0.5.The hardness of copper is effectively improved.The cross-section hardness of Cu₅₀Hf₃₆Al₆V₄Nb₃amorphous composite cladding layer changes evenly,and there is an obvious gradient process relative to the hardness of Cu₄₇Hf₄₂Al₆Mo₄Ta₁cladding layer.Through the analysis of the fracture behavior of the cladding layer,it is confirmed that the metallurgical bonding between the two cladding layers and copper matrix is relatively firm.According to the analysis of the fracture morphology of the cladding layer,the two cladding layers show obvious brittle fracture characteristics.