Effect of rare earth La on microstructure and properties of 8021 aluminum foil blank under large plastic deformation
The effects of rare earth La on the microstructure and properties of 8021 aluminum foil blank under large plastic deformation are studied by OM,SEM,vickers hardness tester and Tensile testing machine.The results show that rare earth La can increase the number of crystal nucleus during the solidification process and significantly refine the grains.Rare earth La has greater vacancy binding energy than Al,which inhibits Al atoms thermal diffusing to vacancies and makes the size of recrystallized grains smaller.After adding rare earth La,a film with rich rare earth is formed on the particle surface,which inhibits the diffusion behavior of Fe atoms and leads the growth momentum of iron-rich particles in the length direction insufficient during annealing.After rolling deformation,the original nee-dle-like iron-rich phase particles are broken into several sections under shear stress.After annealing,the broken needle-like iron-rich phase particles gradually coarsen and eventually evolve into short rod-shaped fine particles,which are evenly distributed at grain boundaries.Rare earth La can significantly refine the as-cast structure and in-hibit the grain growth during annealing,thus improving the tensile strength,elongation,and microhardness of the alloy.At the same time,the short rod-shaped iron-rich phase can anchor more dislocations and more capable to withstand the shear stress during the tensile process,can better coordinate the plastic deformation and improve the elongation of the alloy.
large plastic deformationiron-rich phase particlesrecrystallizationmicrostructure and properties
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