Mechanical Properties And Microstructure Of 2024 Aluminum Alloy Subject To Electric And Magnetic Physical Field Tensile Test

2024 aluminum alloy is one of Al-Cu-Mg series aluminum alloys,which is a kind of high strength hard aluminum,and it is widely used in the aerospace field.But now to improve its plastic deformation capacity is facing many great challenges.In this paper,based on the magnetostatic and electroplastic effect,the effects of the electromagnetic field on the plastic deformation process and the deformation ability of the alloy were studied by using the pulsed magnetic field and the electric field and the electromagnetic coupling field.The influence of different pulse magnetic induction intensities and pulse numbers,different current intensities and electromagnetic field coupling parameters on the microstructure and properties of 2024 aluminum alloy was investigated by means of metallographic,scanning electron microscopy,transmission electron microscopy,backscattering EBSD,XRD and mechanical properties.The effect of magnetic field stretching on the microstructure of 2024 aluminum alloy was studied,and the effect of magnetic field on the plastic deformation ability of the alloy was analyzed.The main achievements of this paper include the following four aspects:?1?The experimental results show that the tensile strength and elongation of the 2024 aluminum alloy increase with the increase of the magnetic field intensity,and they will reach the optimal value at B=1T when the pulse number is constant?N=30?.At B=1T,the elongation???and strength??_b?are 14.7% and 425 MPa,respectively,and the amplifications are 13.1% and 3.7% respectively in comparison to the untreated sample.When N=30,the tensile strength and elongation of the material reach the maximum value synchronously,so the optimal magnetic field treatment parameters B^*=1T and N^*=30 are optimized;When the B increases from 0.5T to 1T and N increases from 0 to 30,the dislocation density increases with the magnetic induction intensity and the pulse number augment,and the dislocation intensification leads to the increase of the tensile strength.Dislocation organization tends to order under the low field strength and the low pulse number conditions,which promote the plasticity of the material;When B>1T and N>30,magnetoplasticity effects weak and dislocation pile-up appears,which is not conducive to the performance of the material.?2?As for the results of electric field and electromagnetic field tensile tests: under the single electric field,the average tensile strength??_b?of samples is 411 MPa,which is almost the same compared with the 410 MPa of the untreated sample.The elongation???is 14.3% on average,which is enhanced by 10% in comparison to the 13% of the untreated sample.Especially at I=1.6A,the elongation???arrives at the 15.3%,amplified by 17.7%.Meanwhile the relevant tensile strength is 410 MPa that is the same that of the untreated sample.The optimized condition of I?9?=1.6A is determined;under the electromagnetic coupling field,The average ?_b is 419 MPa,which is increased by 2.2% compared with that of the untreated sample,the average elongation???is 15.3% whose increment is 17.7%.The electromagnetic coupling field compared with that of the single electric field,The elongation and tensile strength increased by 7% and 1.9%,respectively.The values of tensile strength and elongation reach optimal at I=1.6A,B=1T,?_b is 413 MPa and ? is 16.6%,which are increased by 0.7% and 27.7%,respectively.?3?Due to the magnetoplastic effect,the dislocation density of the material increases treated by the pulsed magnetic field,while reducing the energy required for the dislocation nucleation,strengthening the dislocation motion and promoting the release of the internal stress of the material;At B=1T and N=30,The magnetic field exerts a positive effect on MPE,which can improve the pile up of dislocation effectively.The magnetic field will accelerate the state conversion of a radical pair generated between the dislocation and precipitates?obstacles?from singlet to the triplet state,and the bonding energy between dislocation and obstacle will be lowered down.The moving flexibility of dislocations will be enhanced.On the basis of first principle,the magnetic property of main precipitate ??Al-₂Cu?is ascertained as paramagnetic,which is beneficial to the MPE exertion.?4?After electric field treatment the 2024 aluminum alloy,the nucleation rate of dynamic recrystallization increases and the growth rate of crystal nucleus decreases,which results in the decrease of grain size;The dislocation density near the fracture surface decreases,dislocation entanglement decreases,and the uniformity of plastic deformation is improved,at the same time,the stress concentration reduction and improve the plasticity of the material.After electric magnetic coupling field treatment the materials,the mechanical properties of the material are increased compared with that of a single magnetic field and a single electric field,the mechanism includes magnetoplasticity effect and electro plastic effect,and the research in this part needs further study.