Research On The Preparation Of High Strength Aluminum Lithium Alloy

Aluminum alloy is an important material in 21th century,which has great application in production and life.After entering the new century,the concept of green retainable development puts forward higher requirements for the lightweight of aluminum alloy.The addition of Li in aluminum alloy can effectively reduce the density,but it also needs to overcome the enhancement of anisotropy.In this paper,through OM,XRD,SEM,tensile tests,the effects of Li addition and changing forming method on the microstructure,mechanical properties and corrosion resistance of alloy are investigated.The conclusion is as follows:?1?The density of Li-containing alloy decreases,but coarse dendrite structure and serious segregation are formed in as-cast structure.The mechanical properties of Li-containing ingots are deteriorated and the corrosion resistance decreases.Rolling deformation obviously improves the homogeneity of microstructure.However,the mechanical properties of deformed structure decreases due to the coarse Li₃CuAl₅particles and the decreasing of strengthening phase,but the corrosion resistance of the alloy is improved at the same time.?2?Dense clusters of second phase particles can be formed by cross rolling.These second phase particles can produce strong stress concentration and form more distortion regions.By increasing dislocation density,decreasing recrystallization activation energy and increasing nucleation particle,the effect of grain refinement can be achieved.Different hot rolling mode can not change the type of texture.But cross rolling changes the distribution of the coarse second phase particles and increase the degree of recrystallization,so that the texture type of T6 state changes form B,S,C,G of unidirectional rolling to RB,G,at the same time,the strength of texture is greatly reduced from 8.36 to 5.12.Cross rolling can improve the mechanical properties of alloy,the average tensile strength of cross-rolled alloy increase from 552 MPa to 564 MPa,the average elongation increase from 8%to 11%.In addition,the IPA index has also been improved shows that cross rolling can obviously reduce the anisotropy of alloy.However,the dense clusters of coarse second phase particles can be formed after cross rolling,which will accelerate the corrosion reaction and decrease the corrosion resistance of alloy.