Effects of Al-5Nb-B Refiner on Microstructure and Properties of Al-12Si Alloy
The Al-5Nb-B grain refiner was prepared by fluorinated salt method,and the prepared refiner was added to Al-12Si alloy with different contents(0.0wt%,1.5wt%,3.0wt%,4.5wt%).Optical microscopy and scanning electron microscopy were used to observe the microstructure of Al-12Si alloy with different grain refiners,and the mechanical properties were tested at room temperature in an electronic universal testing machine(D2-02001).The effects of Al-5Nb-B grain refiner on the microstructure and tensile properties of near-eutectic Al-12Si alloy were studied.The results show that the Al-5Nb-B grain refiner prepared by fluorinated salt method mainly contains Al3Nb particles with an average size of 20 μm and NbB2 particles with an average size of 5 μm.With the increase of the Al-5Nb-B grain refiner content,the α-Al grain size in Al-12Si alloy decreases from 1864 μm without addition to 396 μm,the tensile strength of as-cast alloy increases from 128 MPa to 145 MPa,and the elongation after fracture increases from 6.9%to 9.8%.The Al-5Nb-B grain refiner prepared by the fluorinated salt method increases the nucleation number of NbB2 in the Al-12Si alloy melt,effectively refines the α-Al matrix,and improves the mechanical properties of the alloy.
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