Preparation And Reaction Properties Of Ni/Al Micro-nano Energetic Materials

Ni/Al energetic material is a kind of composite material with certain strength and energy density.It is paid more attention due to its intense chemical reaction and produce detonation effect under the condition of high temperature or high speed i MPact.At present,the magnetron sputtering method is mainly used in the preparation of Ni/Al micro-nano energetic materials and the research is mainly focus on the high temperature characteristics and ignition performance of Ni/Al intermetallic compounds.In this paper,the micro-nano scale Ni/Al energetic materials were prepared by accumulative roll bonding,and then the mechanical properties and reaction performance were studied.The results of these researches can lay the preliminary theoretical foundation for the applications in the field of aerospace combat.Firstly,Ni/Al composite laminates were prepared by accumulative roll bonding and the interfacial structure was studied.The results indicate that the thickness of the Ni/Al composite laminates decreases with the increase of rolling passes.The hard phase Ni has lost its lamellar structure and gradually shrinks or even ruptures during the rolling process due to the large rheological resistance.The broken nickel fragments are embedded in the aluminum matrix finally.The higher the nickel content,the smaller the interlayer thickness of the Ni/Al composite laminates after multiple passes.When the initial thickness ratio is 1:1,the nickel foils and aluminum foils thickness is about 0.1?m after 18 passes of accumulative roll bonding.X-ray diffraction(XRD)analysis of the materials with four layer thickness ratios did not reveal the formation of intermetallic compounds,which provided a good possibility for the exothermic effect.Secondly,the mechanical properties and fracture morphology of Ni/Al composite laminates were analyzed.It is found that the original layer thickness ratio and rolling pass have an important influence on the mechanical properties of the Ni/Al composite laminates.The tensile strength of Ni/Al laminates decreases and the elongation increases gradually with the increase of aluminum content.However,the tensile strength of Ni/Al laminates is generally increased and then decreased with the increase of rolling passes.When the Ni/Al layerd thickness ratio is 1:1,the tensile strength can reach as high as 395 MPa after 8 passes of accumulative roll bonding.The elongation rate of Ni/Al composite plate is low at about 5% in all rolling passes,and the elongation decreases with the increase of the rolling pass.The fracture modes of nickel and aluminum in Ni/Al laminates are different: the nickel material is brittle fracture,while the aluminum material is ductile brittle mixed fracture.Finally,the reaction properties of the Ni/Al composite plate were studied by differential scanning calorimetry(DSC).It was found that the energy density of the Ni/Al laminates increases with the interlayer thickness decreases.When the initial thickness ratio is 1:1.4,the exothermic peak reached to 1362.5J/g which was about 92% of the theoretical value after 13 rolling passes.The initial reaction temperature of the material decreases with the increase of the rolling pass,and increases with the increase of aluminum content.The formation sequence of Ni/Al intermetallic compounds follows certain rules.As the temperature increases,the NiAl3 appeared earliest and then reacts with Ni to produce Ni2Al3,Ni2Al3 reacts with Ni to produce stable intermetallic compound NiAl.