复合稀土与Al-Ti-B协同作用对6061铝合金微观组织和力学性能的影响  

Synergistic Effect of Misch Metal and Al-Ti-B on the Microstructure and Mechanical Properties of 6061 Aluminum Alloy

作　　者：陈志强 胡文鑫 石磊[2] 王玮 CHEN Zhiqiang;HU Wenxin;SHI Lei;WANG Wei(State Key Laboratory of Baiyunobo Rare Earth Resource Research and Comprehensive Utilization,Baotou 014030,China;Baotou Research Institute of Rare Earths,Baotou 014030,China)

机构地区：[1]白云鄂博稀土资源研究与综合利用国家重点实验室,内蒙古包头014030 [2]包头稀土研究院,内蒙古包头014030

出　　处：《铸造技术》2022年第10期897-905,共9页Foundry Technology

基　　金：内蒙古自治区自然科学基金(2021MS05049);白云鄂博稀土资源研究与综合利用国家重点实验室项目(2021Z2348)。

摘　　要：6061铝合金中晶粒和第二相的形态、尺寸及分布对合金的综合力学性能有显著影响。本文通过研究不同比例混合稀土LaCe与Al-Ti-B复合添加对6061铝合金显微组织和晶粒细化效果的影响,讨论了稀土的存在形式及其对合金第二相的作用,分析了稀土与Al-Ti-B协同作用对合金拉伸性能和断口形貌以及导热率的影响。结果表明,添加稀土与Al-Ti-B中间合金后,合金的晶粒尺寸减小;稀土主要以Al FeSiREMg相和Al Si Ti Mg RE的形式分布于晶界。此外,稀土的加入促使β-Al FeSi相转变为α-Al FeSi相,Mg2Si相尺寸减小,形成了Al FeSi、Al FeSiREMg等多种复杂化合物,并减少了晶界富铁相的杂质。与未添加稀土的6061合金相比,添加0.05%LaCe和0.2%Al-Ti-B(质量分数)中间合金的6061铝合金拉伸强度和伸长率以及导热率分别提高15.3%、80%和9%;同时,稀土与Al-Ti-B中间合金结合后,断口形貌中粗糙、不规则韧窝转变为小韧窝,断裂形式为韧性断裂。The morphology, size and distribution of the grain and the second phase of 6061 aluminum alloy have significant effects on the comprehensive mechanical properties of the alloy. In this paper, rare earth and Al-Ti-B master alloys were added to 6061 aluminum alloy, which was used to compare grain-refining effects, investigate the manner of existence of rare earth, determine the influence and mechanism on the second phase, and analyze the influence of rare earth on the tensile properties, fracture morphology and thermal conductivity of the alloy. The results show that adding the rare earth combined with the Al-Ti-B master alloy lowers the grain size of the 6061 alloy. Rare earth elements are mainly distributed at grain boundaries in the form of the Al FeSiREMg phase and Al Si Ti Mg RE phase. In addition, the addition of rare earth promotes the transformation of the β-Al FeSi phase into the α-Al FeSi phase, decreases the size of Mg2Si, forms various complex compounds(e.g., Al FeSi, Al FeSiREMg and other complex compounds), and reduces the impurity of the Fe-rich phase at the grain boundary. Compared with 6061 alloy without rare earth elements, the tensile strength, elongation and thermal conductivity of 6061 alloy with 0.05% LaCe combined with 0.2% Al-Ti-B(mass fraction) master alloy are enhanced by 15.3%, 80% and 9%, respectively. Meanwhile, the rough and irregular dimples formed in the fracture morphology change into small dimples, and the form of fracture is ductile fracture.

关 键 词：6061铝合金 稀土 AL-TI-B 细化作用 力学性能 作用机理 

分 类 号：TG146.45[一般工业技术—材料科学与工程]