Effect of rare earth scandium and erbium on the microstructure and mechanical properties of A356 alloy
Effects of rare earth elements Sc and Er on the microstructure and mechanical properties of A356 alloy were studied.The differences in microstructure and properties of different alloys were compared and studied through metallographic observation,mechanical property testing,scanning electron microscopy,and X-ray diffraction analy-sis.The results showed that when 0.30％Sc and 0.28％Er were added to A356 alloy,the average size of eutectic silicon could be reduced to 2.38 pm,and the morphology also changed to small granular shapes;When La or AlTiB is added separately,the average size of eutectic silicon is 8.26 μm and 6.02 μm,respectively,with short rod shaped and pointed sheet shaped morphology,indicating that the composite addition of Sc and Er has a better grain refine-ment effect than the single addition of La or AlTiB,significantly reducing the grain size of eutectic silicon and impro-ving its morphology.Correspondingly,the tensile strength of A356(Sc,Er)alloy reached 207.29 MPa,with an e-longation of 6.1％.Compared with A356(La)alloy andA356(AlTiB)alloy,the tensile strength increased by 40.79％and 37.94％respectively,and the elongation increased by 90.63％and 60.52％respectively.The strength and toughness of the alloy were significantly improved,which is not only related to the grain refinement of eutectic silicon,but also to the dispersion distribution of Al3Sc,ScSi2,and ErSi2 particles.these particles promotes fine grain strengthening and dispersion strengthening.The effect of the material has improved the mechanical properties of the alloy.
A356 alloySc and Ergrain refinementorganizationmechanical property
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