稀土变质对Al-Fe系合金组织及力学性能的影响

发布时间：2018-01-10 00:27

  本文关键词：稀土变质对Al-Fe系合金组织及力学性能的影响　出处：《内蒙古工业大学》2015年硕士论文　论文类型：学位论文

  更多相关文章： 铝合金 稀土变质 富铁相 退火 轧制

【摘要】：Al-Fe金属间化合物具有优良的耐热、耐磨和抗氧化性能,但对于Al-Fe系合金,由于Al-Fe金属间化合物其形貌呈粗大的针状或片状结构,严重割裂基体和影响合金的力学性能,所以本文主要研究利用富Ce混合稀土改善和提高Al-1wt%Fe、8011A及高铁含量铝铁合金的组织和力学性能。首先添加不同含量的富Ce混合稀土对铝铁合金进行变质处理,其次对合金进行均匀化退火,最后通过冷轧塑性变形工艺细化合金组织、改善富铁相有害形貌,从而有效地提高铝铁合金的力学性能。利用光学显微镜,XRD,SEM及EDS等方法分析金相显微组织、物相组成、元素含量及分布。在对Al-1wt%Fe合金的研究中表明,当富Ce混合稀土的加入量为0.3wt%时变质效果最佳,晶粒明显细化,同时Al-Fe相也得到改善,由最初的片状或针状转变为短杆状或椭球状;经480℃、24h均匀化退火后晶界处针状或杆状Al-Fe相有熔断现象;经冷轧变形后发现晶界处Al-Fe破碎,晶粒再次细化,且随着变形量的增加,Al-Fe相的破碎更加充分,分布也更加均匀。试验证明铸态时未添加稀土时合金抗拉强度为84.03MPa,稀土量为0.3wt%时抗拉强度为86.42MPa;经80%冷轧变形后,含稀土为0.3wt%的合金有最大的抗拉强度值为163.2MPa。在对8011A铝合金的研究表明,其变质效果最佳的富Ce稀土加入量仍然为0.3wt%,由于其他合金元素的加入,其形貌由之前的杆状或针状更多的转变为多边形片状、短杆状或球状;经450℃、24h退火后晶界处富铁亦有熔断的现象,针状的富铁相断为杆状;冷轧变后,晶粒的细化程度进一步提高,在挤压力的作用下晶界处富铁相充分破碎,均匀的弥撒的分布于基体中。实验表明铸态时未添加稀土变质的合金抗拉强度为116.32MPa,稀土量为0.3wt%时抗拉强度为117.46MPa;当经过80%冷轧变形后,含稀土为0.3wt%的合金有最大的抗拉强度值为202.65MPa。在对高铁含量铝铁合金的研究表明,随着铁含量的增加,合金基体中Al-Fe相从短杆状变为长针状或有棱角片状,当Fe含量为6wt%时,变为粗大的针状或雪花状。当富Ce稀土的加入量为0.7wt%和0.9wt%时变质效果最好,合金基体中雪花状、粗板状和大针状的富铁相有明显的减少,且部分转变为细针状、细板状、短杆状和椭球状,退火后Al-Fe相有熔断的现象即针状的Al-Fe断裂为杆状,同时基体中球状的Al-Fe相数量明显增加,说明热处理对Al-Fe有一定的球化效果。
[Abstract]:Al-Fe intermetallic compounds have excellent heat resistance, wear resistance and oxidation resistance, but for Al-Fe alloys, the morphology of Al-Fe intermetallics is coarse needle-like or flake. The mechanical properties of the alloy were seriously severed and the mechanical properties of the alloy were affected. Therefore, the use of ce rich mixed rare earths to improve and improve the Al-1wt was studied in this paper. The microstructure and mechanical properties of Al-Fe alloy with 8011A and ferric iron content. Firstly, the Al-Fe alloy was modified by adding different content of mixed rare earth with rich ce, and then homogenized annealing was carried out. Finally, the microstructure of the alloy was refined by the cold rolling plastic deformation process, and the harmful morphology of the Fe-rich phase was improved, thus the mechanical properties of the Al-Fe alloy were effectively improved. The microstructure, phase composition, element content and distribution of Al-1wt alloy were analyzed by SEM and EDS. When the amount of ce rich mixed rare earth is 0.3 wt%, the modification effect is the best, the grain size is obviously refined, and the Al-Fe phase is improved, from the initial flake or needle to the short rod or ellipsoid. After annealing at 480 鈩，

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