Study Of Al/Ni Multilayer Foils On Self Propagating Reaction And Simulation Of Welding Temperature Field

With the rapid development of various new and advanced technologies,higher requirements have been put forward for material joining technology.Al/Ni micro laminated foils as a new type of composite materials containing energy,the self propagating reaction has a low heat effect on the interconnection of the parent materials,suitable for connecting devices or temperature sensitive materials,suc h as in space,a miniature integrated circuit electronic packaging and welding field of heterogeneous materials.The whole welding process is completed in a very short time,and it will not affect the surrounding components.It is a new approach to realize special welding and has important practical application value.In this paper,Al/Ni micro-stack foils were prepared by high power electron beam physical vapor deposition method.In the deposition process,if the substrate temperature is too high,will cause the laminated foil reaction,therefore the substrate temperature during the deposition were calculated,based on the calculation results,the optimization design of substrate for temperature is obtained.According to the characteristics of microstructure materials prepared by EBPVD,by the second law of thermodynamics,Allen formula and short circuit diffusion based on the basic principle,with columnar crystal structure of Al/Ni laminated foil self propagating reaction rate equation is derived.Taking the single layer thickness,modulation period,total thickness and grain boundary content as variable parameters,a finite element model is established to simulate the welding temperature field with Al/Ni laminated foil as moving heat source.The influence of the rate of self propagating reaction and the thickness of filler metal on the welding temperature field is studied.The optimum welding process is obtained.The results show that the rising rate of stainless steel substrate temperature equipment is too fast,Al and Ni in the preparation process will react,block type heat sink substrate can effectively reduce the temperature rise of samples obtained no impurity phase,the electron gun current value will affect specimen thickness,total thickness,and microstructure.It is found by theoretical calculation that when the product of self propagating reaction is different,its adiabatic temperature is also different.Generally,the temperature need to reach 1800 K and the reaction can be self sustained.Self propagating reaction rate is related to and thickness,total thickness,t factors of grain boundary content,this article from the perspective of atomic diffusion and thermal diffusion quantitative by Al/Ni laminated foil self propagating reaction rate equation,and the measurement results obtained in the experiment are similar,verify the rationality of the model.The influence of the rate of SHS reaction and the thickness of Sn solder on the welding temperature field was investigated.It was found that in a certain range,the faster the self propagating reaction rate is,the lower the overall temperature of the solder when the solder thickness was certain.Self propagating reaction rate optimal selection,increase the solder thickness,the results show that a certain range of solder thickness increases,the temperature is lower,and the quantitative relationship between approximately,each increase of solder thickness is 10?m,the highest temperature is reduced by about 15?,the criterion of solder thickness influence on the temperature field is 1.5?/?m.