Intra/interlayer atomic diffusion behavior of Al/Ni reactive multilayer nanofoils excited by electrical/thermal/mechanical multi-fields
Metal reactive multilayer nanofoil is a laminated structure film formed by alternately arranging metals with a thickness of 10-100 nm.Under the action of external physical fields such as electrical,thermal and mechanical,metal reactive multilayer nanofoil releases a large amount of heat by the chemical process of forming compounds through atomic diffusion and the physical process of grain growth,which is widely used in micro-nano joining,material synthesis and other fields.However,the atomic diffusion mechanism of metal reactive multilayer nanofoil under different physical fields and their composite excitations is still unclear.In this study,the molecular dynamics model of Al/Ni reactive multilayer nanofoils under the action of multi-physics fields was established by constructing the kinetic potential functions of atoms/charges,and the laws of atomic motion under the excitation of different physical fields were obtained.An experimental system for in-situ characterization of self-propagating reaction properties of reactive multilayer nanofoils under the action of electrical/thermal/mechanical multi-fields was established,and the characteristics of the self-propagating reaction products of reactive multilayer nanofoils were obtained by transmission electron microscope(TEM).The findings showed that the thermal field induced interlayer diffusion by shortening the diffusion distance,while promoting intralayer diffusion.The mechanical field promoted the interlayer diffusion of atoms in the width-thickness plane through the deformation within the atomic layer.The electric field suppressed intralayer diffusion by affecting the directional migration of metal atoms.The electrical/thermal/mechanical multi-fields recombination could stimulate the intra-layer/inter-layer diffusion behavior of metal atoms,promoting the self-propagating reaction velocity and heat generation temperature.Taking the Al/Ni reactive multilayer nanofoils as an example,the self-propagating reaction velocity under the action of electrical/thermal/mechanical multi-fields was increased by four times,and the heat generation temperature was increased by 61％.
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