Preparation of a New Al-Ti-Nd Master Alloy and Its Refinement and Modification Effect on Al-10Si Alloy
A new type of Al-3Ti-4.5Nd master alloy was prepared by aluminum in-situ melt method.The microstructure of Al-3Ti-4.5Nd master alloy was analyzed by means of X-ray diffraction(XRD)and scanning electron microscopy(SEM).The effects of Al-3Ti-4.5Nd master alloy on the microstructure and mechanical properties of Al-10Si alloy were investigated.The experimental results show that when the addition amount of Al-3Ti-4.5Nd master alloy is 0.15％,the macrostructure of Al-10Si alloy is refined from coarse columnar grains to fine equiaxed grains,and the secondary dendrite arm spacing is reduced from 16.69 μm to 13.44 μm.The eutectic silicon changes from coarse needle-like to short rod-like,and the average length decreases from 26.75 μm to 16.47 μm.The tensile strength increased from 165.86 MPa to 177.43 MPa,and the elongation increased from 4.21％to 6.72％.The quality index Q of the alloy increased from 259.50 MPa to 301.54 MPa,an increase of 16.2％.The Ti2 Al20Nd phase can effectively refine the α-Al phase.The rare earth elements promote the formation of twins in eutectic silicon and improve the morphology and size of eutectic silicon.
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