微量稀土元素对铝锌合金组织和性能影响的研究

发布时间：2018-06-21 01:13

  本文选题：金相组织 + 稀土元素　； 参考：《重庆理工大学》2017年硕士论文

【摘要】：本论文采用铸锭冶金法制备了铝锌二元合金,并在此基础上,制备了5种不同Ce含量的Al-32%Zn-0.35%Zr-0.15%Cr-0.12%Ti-XCe(X=0,0.05,0.1,0.2,0.3)合金和5种不同Er含量的Al-32%Zn-0.35%Zr-0.15%Cr-0.12%Ti-XEr(X=0.05,0.1,0.2,0.3,0.4)合金。利用金相显微镜、差示扫描量热分析仪、X射线衍射仪、维氏硬度仪、扫描电子显微镜及能谱分析以及抗拉性能、阻尼性能测试等手段,研究了稀土元素Ce、Er微合金化以及热处理分别对铝锌合金组织与性能的影响规律,并得到如下主要结论。(1)在Al-32%Zn合金中组合添加微量合金元素Zr、Cr、Ti后,合金的铸态组织得到明显的细化,粗大的树枝晶消失,转为细小、均匀的等轴晶,晶粒的平均尺寸由550μm减小为90μm。合金的抗拉强度、硬度和延伸率有所提高,分别达到251MPa、111HV和6.1%,与未添加Zr、Cr、Ti合金相比,分别提高了6.8%、8.8%和10.9%。Al-32%Zn-0.35%Zr-0.15%Cr-0.12%Ti合金经420℃×3h+110℃×2h热处理后硬度达到144HV,与未热处理合金相比,提高了29.7%。(2)在Al-32%Zn-0.35%Zr-0.15%Cr-0.12%Ti铸态合金中添加稀土元素Ce后,合金的铸态晶粒明显细化,合金的等轴晶晶粒尺寸随Ce含量的增加呈先减小后增大的趋势,并且Ce在合金中以方块状含Ce金属间化合物形式存在。当加入0.1%Ce时,合金晶粒平均尺寸最为细小,约为35~45μm,其抗拉强度、延伸率、阻尼性能和硬度分别为280MPa、6.7%、0.043(A=800×10-6)和121HV,与未添加Ce合金相比,分别提高了近11.6%、9.8%、34.4%和9.0%。经420℃×3h+110℃×2h热处理后,Al-32%Zn-0.35%Zr-0.15%Cr-0.12%Ti-0.1%Ce合金达到时效硬度峰值为148HV。(3)在Al-32%Zn-0.35%Zr-0.15%Cr-0.12%Ti铸态合金中加入稀土元素Er后,合金的铸态晶粒明显细化,合金的晶粒尺寸呈先减小后增大趋势,Er在合金中部分以方块状含Er金属间化合物形式存在,部分固溶在α基体中。当加入0.2%Er时,合金晶粒平均尺寸最小,约为25~35μm,其抗拉强度、延伸率、阻尼性能和硬度分别为333MPa、8.0%、0.061(A=800×10-6)和127HV,与未添加Er合金相比,分别提高了近32.6%、31.2%、90.6%和14.4%。经420℃×3h+110℃×4h热处理后,Al-32%Zn-0.35%Zr-0.15%Cr-0.12%Ti-0.2%Er合金达到时效硬度峰值为153HV。稀土元素Er的添加,延缓了合金达到时效硬度峰值的时间。(4)在Al-32%Zn-0.35%Zr-0.15%Cr-0.12%Ti合金铸态组织的改善和力学性能的提高方面,稀土元素Er的作用效果优于稀土元素Ce。
[Abstract]:Al-32Zn-0.35Zr-0.15Cr-0.12Cr-0.12Cr-0.12Cr-0.12Cr-0.12Cr-0.12Cr-0.12Cr-0.12Cr-0.12Cr-0.12Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.15Cr-0.12Ti-XErX0.050.30.4) alloys were prepared by ingot metallurgical method in this paper. By means of metallographic microscope, differential scanning calorimeter, X-ray diffractometer, Vickers hardness tester, scanning electron microscope and energy spectrum, tensile and damping properties, etc. The effects of the rare earth element CeCe er microalloying and heat treatment on the microstructure and properties of Al-Zn alloy were studied. The as-cast microstructure of the alloy was obviously refined, and the coarse dendrite disappeared and changed into fine and uniform equiaxed crystal. The average grain size was reduced from 550 渭 m to 90 渭 m. The tensile strength, hardness and elongation of the alloy increased to 251 MPA / 111HV and 6.1, respectively. Compared with the alloy without ZrCrNTi, the tensile strength, hardness and elongation of the alloy were increased by 6.8% and 10.9%, respectively. The hardness of the alloy was 144HVHVcompared with that of the alloy treated at 420 鈩，

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