Research On Laser High-speed Impact Welding Between Fe-based Amorphous Alloys And Crystalline Metal

In recent years,with the rapid development of microelectronics and electric system,some small and lightweight amorphous alloys have attracted people's extensive attention due to their low loss,high magnetic permeability and unique amorphous structure.However,the welding of amorphous alloys with crystalline metal in the microscale is not easy to realize in the process with amorphous structures unchanged,which restrains the application in industry.The laser high-speed impact welding technology has a remarkable advantage in the connection of dissimilar materials in the microscale.In this dissertation,the welding of Fe-based amorphous alloys with crystalline metal is studied by means of laser high-speed impact welding.The main research contents and results are as following:Firstly,the mechanism of the interaction between laser and materials was studied,and the causes of shock wave formation under high-speed impact welding process was analyzed;The preconditions of formation for high-speed impact welding process was established,this dissertation also introduced the interface characteristics of high-speed impact welding;In addition,the formation mechanism of interface waves were studied and discussed.Then,the welding of T2 copper and Fe-based amorphous alloys(GB1K101)by laser high-speed impact welding was studied.The experimental results showed that the wavy welding interface and better welding quality between annealed T2 copper with Fe-based amorphous alloys were obtained;Springback occurred on the base plate and flyer plate after impact welding,and the surface wave was formed on the flyer plate;X-ray energy dispersive spectroscopy(EDS)analysis results showed that there were no element diffusion occurred and intermetallic compounds formed in the welding interface;The welding interface was straight or wavy under different laser energy;X-ray diffraction(XRD)test showed the amorphous structures of Fe-based amorphous alloys unchanged after impact welding under lower laser energy and still maintained the excellent properties of amorphous structures;The hardness on the welding interface after impact welding was significantly improved;The tensile shear forces and peeling forces increased with the increase of laser energy,and the fractured location was on the side of copper coil;The welding interface morphology changed from wavy to flat as the thickness of the flyer plate increased.Lastly,the welding of Al and Fe-based nanocrystalline alloys(GB1K107)was also studied by laser high-speed impact welding,the microstructure and mechanical properties of welded samples were observed and tested under different standoff distance.Research results are as following: The welding of Al and Fe-based nanocrystalline alloys has been successfully realized;With the increase of the standoff distance,severe plastic deformation occurred on the surface of flyer plate,and the welding interface changed from flat to wavy,finally to the wavy interface with partial melting layer;EDS detected there were weak elements diffusion occurred on the partial melting region when the standoff distance was larger,and the thickness of the diffusion layer was about 2.5?m;The welding interface varied from flat to wavy whether laser energy or standoff distance increased;The failure loads of tensile shear test and peeling test increased firstly and then decreased with the increase of the standoff distance,the tensile shear test and peeling test showed the failure location of welded sample were on the edge of flyer plate.The research of this dissertation will provide a new way for the connection between Fe-based amorphous alloys and crystalline metal in the microscale,and further provide theoretical and experimental guidance for industrial applications.