| The magnesium alloys have been widely concerned in transportation,aerospace and other fields because of its characteristics of light weight and highstrength.However, the low corrosion resistant capacity, low toughness and otherdisadvantages have restricted the development and application of itscharacteristics of light weight and high strength seriously.Therefore, in order tosolve the problems of low corrosion resistance and low plastic deformationability of magnesium alloys, we can improve the magnesium alloys propertiesand broaden its application by compounding other materials of good corrosionresistance snd good toughness.In this paper, it is based on the magnesium alloy AZ31B, industrial puretitanium TA2and aluminium alloy6061as the experimental materials.TheMg/Ti and Mg/Al/Ti composite plates were fabricated by explosive weldingsuccessfully.The microstructure of interface was analyzed by optical microscope,scanning electron microscopy, and energy spectrum analyzer.The mechanicalproperty of the composite plates were investigated by microhardness test, sheartest, tensile test, bending test and impact test systematically.It can be concluded that the wave morphology of explosive weldinginterface was fromed by the irreversible and sinuate plastic deformation processof metals under explosive load on the analysis of the explosive welding interface.On the analysis of combination mechanism of explosive welding interface, themetallurgical bonding on the interface was accomplished by three stages.Theyare the formation of physical contact stage, the interfacial chemical interaction stage and the interaction phase and stable interface elements diffusion stage.Microstructure analysis shows that the Mg/Ti composite plate combinedwith good interface.The combination of the interface morphology is mainlycomposed of straight interface and the microwave interface between straight andflat interface.In the magnesium alloy which is on one side of the interface, thegrain tissue deformation is relatively serious.There were mass small flocculentorganization near the interface.It can be found that the adiabatic shear band wasappeard about300microns away from the interface.The existence of adiabaticshear band is caused by severe plastic deformation in the process of explosionwelding.A series of mechanical properties tests were performed on Mg/Ti compositeplate. Microhardness results show that the hardness of titanium was raised from220HV to249HV and the hardness of magnisum was raised from80HV to96HV.This phenomenon was resulted from the strong plastic deformation. Sheartest showed that the composite interface shear strengthwas64MPa.Tensile testshowed that the tensile strength of Mg/Ti composite plate is264MPa. It wasimproved20%of the AZ31B which was210MPa of the tensile strength.Fracture occurred on the magnesium alloy side firstly and there was noseparation between base plate and flyer plate. As the crack extension, the baseplate and flyer plate began to separate. In the last, the composite plate crackeduntil the flyer plate TA2produced tiny necking phenomenon.Bending test resultsshow that Mg/Ti composite plates didn’t separate and produce the crackingphenomenon in positive bending test and negative bending test. This shows thatthe composite plate has the high ability to resistant the layer and the bendingproperty was good of the composite plate.The average value of impact absorbingenergy was12.71J,it was increased1.64times with the AZ31B magnesium alloywhich the average value of impact absorbing energy at room temperature (20C) was4.81J.This is due to the magnesium alloy surface covered by a layer oftitanium which has the good plastic deformation.when two plates werecombined into composite material through metallurgical bonding, the metalinterface and the internal organization changes make the shock resistance ofmagnesium alloy had a enhancement.Heat treatment process of450C×4h,450C×8h,490C×4h and490C×8hhad been carried out on the Mg/Ti composite plate. The element mutualdiffusion occurred on the interface and with the increase of heat treatmenttemperature and heat treatment time, the degree of element defusion couldimprove.At the same time, the tiny amount of aluminum element as a kind oftransition elements in the magnesium alloy AZ31B can promote the elementsdufusion of the interface and improve the bonding strength of composite plate.The research of Mg/Al/Ti three-layer composite plate shows that the Mg/Alinterface and Al/Ti interface occured the wave morphology on the interface. Thewaveform of Al/Mg interface is larger and the wavelength is0.8μm, theamplitude is0.3μm.The waveform of Ti/Al interface is fine and the wavelengthis0.2μm, the amplitude is0.05μm.Mg/Al interface and Al/Ti interface occurredelements defusion and make the each layer accomplish metallurgical bondingsuccessfully. The degree of Mg/Al interface element diffusion was much largerthan the Al/Ti interface. In view of the performance of composite plate for shear,tensile, bending test, the results show that the mechanics performance of theMg/Al/Ti three-layer composite plate is good, the average shear strength of73MPa, it improved obviously compared the Mg/Ti composite plate. Thealuminium as a good transition layer achieve the bonding between Mg and Ti. |
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