Effects of La and Al-5Ti-1B on Microstructure and Properties of A356 Casting Alloy
The effects of rare earth La and Al-5Ti-1B addition on the microstructure of primary α-Al,eutectic Si phase and tensile properties of A356 casting aluminum alloy were investigated.The results indicate that rare earth La and Al-5Ti-1B addition exhibits a multi-refining effect on the microstructure of A356 alloy,including refinement of α-Al grains and the decrease of secondary dendrite arm spacing as well as the transformation of eutectic Si morphology from plate-like to small granular and rod-like.Due to the refinement of α-Al grains and the improvement of the micro-structure of eutectic silicon fibers,the tensile strength,yield strength,and elongation of A356 aluminum alloy treated with 0.3%La+0.15%Al-5Ti-1B refiner are increased by 35%,33%,and 400%,respectively,which far exceeds the performance of traditionally treated ones.After T6 heat treatment,the tensile strength,yield strength,and elonga-tion of refined A356 aluminum alloy are increased by 24%,20%,and 176%,respectively,compared to those of ones without refinement treatment.
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