6061Al/Al2O3金属基复合材料组织和性能

以6061Al作为基质材料,利用液体冶金的搅拌铸造技术及挤压法制备Al₂O₃颗粒增强的金属基复合材料,选取6061Al添加3种质量分数为5%、10%和15%的Al₂O₃为研究对象,以改善6061Al/Al₂O₃复合材料的力学性能。通过SEM分析表明,Al₂O₃颗粒在6061Al金属基体中的分布相当均匀;由X射线衍射试验结果显示,复合材料中只有6061Al和Al₂O₃,且不会影响结晶性及6061Al的组织结构型态。试验结果表明,随着Al₂O₃添加量增加至15%,6061Al/Al₂O₃复合材料的硬度和抗拉强度均有较大提高,但伸长率略有下降,由于材料孔隙率的提升,致密度下降,从而引起材料的硬度略微下降;分析磨损量与Al₂O₃添加量及磨损率与滑动距离的关系,结果显示商用6061Al的磨损率最大,而6061Al/Al₂O₃(15%)复合材料的磨损量最小,并且磨损率最低,这是由于在6061Al中加入Al₂O₃颗粒,Al₂O₃颗粒的存在可以减少磨粒对基体的犁削作用,有效提高基体的耐磨性。深入探讨Al₂O₃颗粒增强的金属基复合材料,发现颗粒增强体以很细的粉末(一般在20 μm以下)加入到金属基中起到提高硬度、强度和耐磨性的作用;然而,Al₂O₃添加量越来越大时,其对6061Al系列材料的硬度、强度和耐磨耗性等性能将起到负面作用。

Microstructure and properties of 6061Al/Al2O3 metal matrix composite materials

An attempt was made to synthesize metal matrix composites by 6061Al as a matrix material reinforced with ceramic Al₂O₃ particles through liquid metallurgical method, and to prepare metal matrix composites reinforced using Al₂O₃ particles by an extrusion method. The 6061 aluminum was chosen as the material of interest, in which the mass fraction of Al₂O₃ was 15%, 10% and 15% to be added, to improve the mechanical properties of the composites. The composites were analyzed using the scanning electron microscope (SEM) and the result showed that the distribution of Al₂O₃ particles in the 6061Al metal matrix was quite uniform. X-ray diffraction results showed that there were only 6061Al and Al₂O₃ in the composites, which would not affect crystallinity and structure of 6061Al. The experimental results showed that the hardness and the tensile strength of prepared composites were increased with the increase in mass fraction of Al₂O₃ up to 15%, but the elongation rate of the composites was decreased slightly. Because the composite material had a higher porosity and lower density, which caused the decrease of material hardness. In addition, comparing with relationship between wear rate and sliding distance, and that between wear and Al₂O₃ content in 6061Al, the commercial 6061Al alloy had the largest wear loss, while 6061Al/Al₂O₃ (15%) composite had the smallest amount of wear and the minimum wear rate, the presence of Al₂O₃ particles could reduce the plowing effect of abrasive particles on the matrix and could effectively improve the wear resistance of the matrix. Through the in-depth discussion on the Al₂O₃ particle reinforced metal matrix composites, the particle reinforcement was added to the metal matrix as a very fine powder (generally less than 20 μm), which played a role in improving the hardness, strength and wear resistance. However, when the content of Al₂O₃ became enough, a negative effect on many properties including hardness, strength and wear resistance occurred.