预氧化温度对纳米SiC颗粒增强镁基复合材料组织及性能的影响

目的 研究预氧化处理对纳米SiC颗粒增强的SiCp/AS81(Mg-8Al-Sn)复合材料显微组织和力学性能的影响,分析其作用机理,最终得到适宜的SiC预氧化温度。方法 采用粉末冶金法制备纳米SiC颗粒增强的SiCp/AS81(Mg-8Al-Sn)复合材料,采用相关仪器设备,对不同温度预氧化处理后的SiC颗粒、AS81和0.50%-SiCp/AS81复合材料物相进行分析,观察其显微组织,并对相关力学性能进行测试。结果 当对SiC颗粒进行不同温度预氧化处理后,SiC颗粒逐渐钝化,并在预氧化温度达到785℃及以上时,SiC外表层逐渐被SiO₂包覆且在985℃时完成完全包覆;AS81复合材料和不同温度预氧化处理的0.5%-SiC_p/AS81复合材料的物相组成都主要为Mg和Mg₁₇Al₁₂,785℃及以上温度预氧化处理后的0.5%-SiC_p/AS81复合材料中的Si元素都呈均匀分布;0.5%-SiC_p/AS81复合材料的硬度、屈服强度、抗拉强度和断后伸长率都高于A...     

Synergistic strengthening of aluminum with SiC by grain refinement and dispersion hardening

This study investigates the synergistic effect of SiC_p on grain refinement and dispersion hardening in Al matrix composites produced by ball milling followed by hot rolling. Al grains are effectively refined by generating significant dislocations and subsequent dynamic recrystallization during milling. The presence of SiC_p stimulates the grain refinement process by more effectively reducing the grain size to ∼40 nm. Furthermore, an increase in the milling speed and duration reduces the grain size and improves the dispersion of SiC_p, thereby enhancing the yield strength without any significant loss of ductility. Consequently, SiC_p/Al composites exhibit a tensile strength of 430.27 MPa with more than 4% of elongation before failure, indicating a strength enhancement of ∼325% compared to the unmilled pure Al counterpart.     

Copper Plating on SiCp by Cooling Crystallization and Its Effects on the Spreading and Infiltration of AlSi12 Alloy Melt

A new cooling crystallization method is applied to plate copper on SiCp. Cu(NO₃)₂·3H₂O is crystallized on SiCp by decreasing the solution temperature, and is heat-treated to obtain CuO coating which is finally reduced to copper coating. Based on the optimizing of SiCp content and CuO reduction temperature, the effects of copper plating on SiCp on the spreading and infiltration of AlSi12 alloy melt are studied. The results show that the optimum coating effect is achieved when the SiCp content is 11.63% and the reduction temperature of CuO is 475 °C. The spreading area of AlSi12 alloy melt on the 15 μm copper-coated SiCp increases by 53.27% compared to the uncoated SiCp when holds at 950 °C for 20 min, indicating that copper plating has a significant improvement on the wettability of AlSi12 melt and SiCp. Additionally, infiltration preparation of copper-plated SiCp/Al alloy composites is achieved at a pressure of 0.3 MPa, but not under pressureless conditions. The main reason for this is the granular Cu on SiCp cannot form a complete Cu film. Therefore, the formation of complete Cu films on SiCp is presumed to be an important development direction for solving the problem of infiltration preparing ultrathick SiCp/Al composites.