Facile Synthesis of Al-20Si@Al2O3 Nanosheets Composite Powders and Its Refinement Performance on Primary Silicon in Al-20Si Alloy

• Key Words:AL-SI ALLOY; MECHANICAL-PROPERTIES; MICROSTRUCTURE; MELT; BEHAVIOR; PHASE; WEAR; SR
• Abstract:In this work, Al(OH)(3) nanosheets are synthesized in situ on the surface of an Al-20Si alloy via the water bath method, and Al-20Si@Al2O3 composites are then obtained after calcination. The growth mechanism of the Al(OH)(3) nanosheets is revealed, and a pathway is demonstrated to obtain Al-20Si@Al2O3 nanosheets with the desired structure and thickness. Furthermore, the influence of different Al-20Si@Al2O3 contents on the primary silicon phase in the Al-20Si alloy is investigated, and the mechanism of such an influence is theoretically analyzed. The mechanical properties of the modified Al-20Si alloy are tested, and the effects of the morphology and particle size of the silicon phase on the alloy properties are studied. The results show that Al-20Si@Al2O3 synthesized in situ by water bath has good dispersion in the melt. There is a lot of gamma-Al2O3 dispersed in the matrix of the alloy, and the primary silicon of the Al-20Si alloy is obviously refined. By increasing the content of the modifier, the average size of primary silicon decreases first and then increases. When 15 wt% of the modifier is added, the refinement effect of primary silicon reaches its peak, and the size of primary silicon is reduced from unmodified 86.4 mu m to 28.5 mu m. The hardness and tensile strength of 75.2 HB and 120.3 MPa are increased to 107.2 HB and 185.9 Mpa by 42% and 55%, respectively. Compared with adding gamma-Al2O3 directly, this experiment provides a simple method to synthesize the modifier, and gamma-Al2O3 can be dispersed evenly in the aluminium-silicon alloy melt more easily by in-situ generation, without ultrasonic treatment or other ways. During mass production, the cost can be better controlled and good results can be achieved at the same time.
• Volume:13
• Issue:3
• Translation or Not:no