| Laser cladding is a kind of surface strengthening technology,in improving the performance of materials,which has a good application prospect.Zr46Cu46Al8 bulk metallic glass with high strength,high hardness,high glass forming ability and excellent mechanical properties was used as substrate material,and Zr46Cu46Al8amorphous powder was used as cladding material to carry out laser remelting on the microstructure of Zr46Cu46Al8 cladding layer.The study on thermodynamic stability and hardness wear resistance lays a theoretical foundation for the industrial application of laser modification of bulk metallic glass.Zr46Cu46Al8 bulk metallic glass was prepared by copper mode vacuum suction casting,Zr46Cu46Al8 amorphous powder was prepared by high energy ball milling,different experimental parameters were designed by orthogonal experiment,and Nd-YAG laser was used to adjust the thickness of coating.Laser remelting is carried out in atmospheric environment with laser current and laser scanning rate.The microstructure of the surface layer was analyzed by XRD,SEM,the crystallization kinetics of bulk metallic glass and amorphous powder and the thermodynamic stability of the cladding layer were studied by DSC,and the different regions of the cladding samples were measured by Vickers microhardness instrument.The friction coefficient of the sample is measured by friction and wear tester.The main conclusions are as follows:（1）The glass transformation and crystallization process of Zr46Cu46Al8 bulk metallic glass has obvious kinetic effect.The crystallization process is first-order crystallization.The direct effects of different milling processes on the preparation of amorphous powders are as follows:milling speed>milling time>ball-to-material ratio.（2）Under the same conditions,the crystallization heat release peak of the bulk amorphous alloy is more acute and more concentrated,and the Tg,Tx,Tp of the bulk amorphous titanium alloy are 712.9,778.6,786.5K are generally higher than that of the amorphous powder 627.7,695.3,775.9K.TheΔTx of Zr46Cu46Al8 bulk metal glass and the amorphous powder are about 65.6K and 67.5K,respectively,and has strong glass forming capacity.（3）The apparent activation energies（Eg,Ex and Ep）of Zr46Cu46Al8 bulk metallic glasses calculated by KISSINGER and OZAWA methods are 260.5 kJ/mol,307.8kJ/mol and 295.9kJ/mol respectively,which are higher than those of amorphous powders corresponding to 157.1kJ/mol,148.5kJ/mol and 112.4kJ/moll.（4）The crystal phase of the Zr46Cu46Al8 alloy powder and the amorphous powder laser cladding is the same as that of the Al2Zr,AlCu,ZrCu and AlCu2Zr phases,but the various laser cladding parameters have a great influence on the structure of the cladding layer.When the laser parameters were 0.3mm in the depth of the coating,the laser scanning speed was 250 mm/min,and the laser current was 200A,only the very weak Al2Zr phase and the crystal diffraction peak of the ZrCu phase appeared,and only a small amount of the crystalline structure was found in the cladding layer.（5）When the laser current is 140A,the scanning speed is 500mm/min and the slotted depth is 0.35mm,the Zr46Cu46Al8 amorphous powder and the bulk metallic glass matrix achieve excellent metallurgical bonding.（6）The thermodynamic stability of the laser cladding of the Zr46Cu46Al8 alloy powder is influenced by the laser cladding parameters,and the DSC curve of the sample under different parameters is obviously different,however the thermodynamic stability of the Zr46Cu46Al8 amorphous powder cladding layer is less effected by the laser cladding parameters,and the difference of the DSC curve of the sample under different parameters is not large,at the same time,the variation range of the thermodynamic parameter value is very small.（7）The average hardness of the samples in the cladding zone of Zr46Cu46Al8 alloy powder and amorphous powder is about 659.7、610.2HV,which is generally higher than that of the basic material hardness 526.4HV,and the average hardness of the Heat affected zone is about 496.8、471.7HV lower than that of the substrate.（8）The friction coefficient of the matrix increases from 0.19 to 0.22 when the friction slip speed increases from 300 to 500 mm/min.When the sliding speed is300mm/min,the friction coefficients of the coating layer between Zr46Cu46Al8 alloy powder and amorphous powder are about 0.22 and 0.17,respectively.When the sliding speed is 400mm/min,the friction coefficients of the coating layer between Zr46Cu46Al8 alloy powder and amorphous powder are about 0.57and 0.24,respectively.When the sliding speed is 500mm/min,the friction coefficient of Zr46Cu46Al8 amorphous powder coating is 0.18. |
