Effects Of Zn,Sc And Zr Additions On Microstructure And Properties Of Al-Mg Alloys Using Equal Channel Angular Pressing

In the context of‘carbon peaking and carbon neutrality’,lightweight Al-Mg alloys play a crucial role in energy saving and emission reduction as green recyclable metal materials.However,with the improvement of industrial level,traditional Al-Mg alloys can no longer meet the requirements of high strength and toughness and high corrosion resistance in the fields of aerospace,ship equipment and automobile manufacturing.Therefore,how to improve the mechanical properties and corrosion resistance of Al-Mg alloy has become a hot issue for current research.In this paper,the microstructure evolution,mechanical properties and corrosion behavior of ECAP Al-6Mg alloy by Zn,Sc and Zr addition were investigated by microalloying and severe plastic deformation techniques,aiming to provide theoretical reference for the development and production of Al-Mg alloy with high strength and high corrosion resistance,the specific research results were as follows:（1）The grains of Al-6Mg alloy gradually refined with the increase of extrusion passes,and the dislocation density increased.Obviousβphase（Al₃Mg₂）precipitates at the grain boundary of the alloy,and theβphase gradually becomes coarse and continuous during the extrusion process.The hardness,YS and UTS of the alloy also increased with the increase of extrusion passes,which were 113HV,271 MPa and 342 MPa after 4 passes,respectively.With the increase of extrusion passes,the corrosion resistance of the alloy gradually decreases.（2）Compared with Al-6Mg alloy,Al-6Mg-1Zn alloy has greater deformation resistance under the same extrusion pass,and the grain structure is characterized by the uneven mixing of original coarse grains and grain boundary fragmentation fine grains.The T phase in the alloy is first generated at the grain boundary,and undergoes growth,fragmentation and dissolution during the extrusion process.The hardness,yield strength and ultimate tensile strength of Al-6Mg-1Zn alloy after 4 passes extrusion are 126 HV,310 MPa and 390 MPa,respectively.Compared with Al-6Mg alloy after 4 passes extrusion,Al-6Mg-1Zn alloy has higher corrosion resistance.（3）the microstructure of Al-6Mg-0.2Sc-0.1Zr alloy is more refined than that of Al-6Mg alloy,before ECAP.The Al₃（Sc,Zr）phase is densely distributed in the alloy and gradually dispersed with the extrusion.Theβphase begins to precipitate after one pass of extrusion,and then gradually coarsens during the extrusion process,but the continuity decreases.Compared with Al-6Mg alloy,Al-6Mg-0.2Sc-0.1Zr alloy has better mechanical properties during extrusion.After 4passes of extrusion,the hardness,YS and UTS values are 129 HV,337 MPa and395 MPa,respectively.The corrosion results show that the corrosion resistance of Al-6Mg-0.2Sc-0.1Zr alloy is significantly improved after adding Sc and Zr elements.Compared with Al-6Mg alloy under the same pass,the corrosion resistance of Al-6Mg-0.2Sc-0.1Zr alloy after 4 passes extrusion is the most significant.