Effects of Rare Earth La,Ce and Y on Microstructure and Mechanical Properties of Al-6.5Si-5.5Cu-0.2Zr-0.01Sr-0.06Ti-0.2RE Alloy
The effects of rare earth La,Ce and Y on the microstructure and mechanical properties of Al-6.5Si-5.5Cu-0.2Zr-0.01 Sr-0.06Ti-0.2RE as-cast alloy were studied by SEM,OM,EDS and tensile test.The results show that the rare earth elements Ce and Y significantly improve the microstructure of the alloy,refine the α-Al phase,and improve the modification effect of the eutectic Si phase,while the improvement effect of La element is poor.The as cast alloys with rare earth elements Ce and Y have high mechanical properties,and the hardness is 76.8 HV and 79.05 HV,respectively,the tensile strength is 182.61 MPa and 216.83 MPa,and the elongation after fracture is 6.03％and 7.84％,respectively.The mechanical properties of the as-cast alloy with La element are lower,the hardness is 73.58 HV,the tensile strength is 160.58 MPa,and the elongation after fracture is 3.21％.The as-cast alloy with rare earth element La has better resistance to intergranular corrosion,smaller corrosion pits,maximum corrosion depth of 90 μm,and corrosion grade of three.However,the intergranular corrosion resistance of the as-cast alloys with rare earth elements Ce and Y gradually deteriorates,and the maximum corrosion depths are 110.21 μm and 145.68 μm,respectively.
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