等离子喷注技术制备Al-Fe合金组织及性能的研究

发布时间：2018-06-28 13:48

  本文选题：Al-Fe合金 + 等离子喷注技术　； 参考：《西华大学》2016年硕士论文

【摘要】：本文回顾了Al-Fe合金国内外研究现状,在前人的研究基础上创新地提出了等离子喷注技术用于制备Al-Fe合金,通过Fe/Al化学体系热力学及动力学的计算,论证了该方法的理论可行性,并在实验中得以验证。针对Fe含量、铝液温度、工作电流等实验参数的影响进行研究,探索其影响规律;通过合金化元素Ni的添加以改善Al-Fe合金组织、提高合金性能;进行热处理实验,对材料进一步处理,并分析其热稳定性。研究结果表明,等离子喷注法利用原位反应生成Al_3Fe合金相,Al_3Fe存在着多边形与细针状两种形态,多边形Al_3Fe由Fe粉与铝液原位反应生成,细针状Al_3Fe由溶解的Fe在凝固时析出生成。Al_3Fe在合金中的体积分数与Fe含量直接相关,Fe含量越高,Al_3Fe体积分数越高,同时使得合金密度、硬度、抗拉强度上升,但Fe含量越高,合金的延伸率越低,并且由于合金液粘度提高而较易产生气孔。铝液温度对合金组织及力学性能有较大的影响,铝液温度越高,Al_3Fe越粗大、且越易趋向长针状生长,从而导致合金力学性能严重下降,对于Al-10%Fe合金,铝液温度在800℃以下时,Al_3Fe颗粒尺寸较小,合金性能较好。工作电流在球化、加热、加速Fe粉方面有有益效果,能促进Fe粉与铝液的反应,但工作电流过高时,将导致Fe粉与铝液的实际反应温度过高,从而增加Al_3Fe长针状的趋势,对于Al-10%Fe合金,工作电流在200A~300A之间时较为适宜。Ni元素对于改善合金组织、提高合金性能上有不错的效果。研究发现,Ni的加入将生成Al_9FeNi,从而抑制细针状Al_3Fe的生成并减少多边形Al_3Fe的尖角部分、细化多边形Al_3Fe颗粒。分析认为,Ni元素的细化机理在于其将与部分溶解于铝液中的Fe一同析出,由于Ni元素占据了Fe的位置,使得Al_3Fe的针状生长方式受阻,因此,Al_3Fe来不及长成针状便凝固下来,从而生成细颗粒态Al_3Fe。但过多的Ni含量将导致Al_9FeNi组织变为粗大,对于Al-10%Fe合金,Ni元素含量最好控制在2%以下。均匀化退火能减少细针状Al_3Fe的含量,在提升Al-Fe合金延伸率上有不错的效果,但会引起合金力学性能的轻微下降,下降原因与合金晶粒的长大有一定的联系。热稳定性实验表明,Al-Fe合金有着较强的热稳定性,材料经640℃的长时间高温退火后,Al_3Fe长大的幅度依然较小,并未呈长针状生长,并且Ni元素的加入能进一步提高材料的热稳定性,这与Ni元素形成的细小弥散相有一定的关系。
[Abstract]:In this paper, the present research situation of Al-Fe alloy at home and abroad is reviewed. On the basis of previous studies, plasma injection technology is proposed to prepare Al-Fe alloy. The theoretical feasibility of this method is demonstrated by the thermodynamic and kinetic calculations of Fe / Al chemical system. It is verified in the experiment. The effects of Fe content, molten aluminum temperature, working current and other experimental parameters were studied, and the influence law was explored. The microstructure and properties of Al-Fe alloy were improved by the addition of Ni, and the heat treatment experiment was carried out. Further treatment of the material and analysis of its thermal stability. The results show that there are polygon and fine needle shape in Al _ 3Fe phase by in-situ reaction of Al _ 3Fe alloy by plasma injection, and Al _ 3Fe polygon is produced by in-situ reaction between Fe powder and molten aluminum. Fine needle Al3Fe precipitates from dissolved Fe during solidification. The volume fraction of Al3Fe in the alloy is directly related to Fe content. The higher the volume fraction of Al3Fe is, the higher the volume fraction of Al3Fe is. At the same time, the density, hardness and tensile strength of the alloy are increased, but the content of Fe is higher. The lower the elongation of the alloy is, the easier the porosity is due to the increase of the viscosity of the alloy solution. The higher the temperature of molten aluminum is, the larger the Al _ 3Fe is, and the more likely it is to grow into a long needle, which leads to a serious decline in the mechanical properties of the alloy. For Al-10 alloy, the temperature of aluminum liquid has a great effect on the microstructure and mechanical properties of the alloy. When the temperature of molten aluminum is below 800 鈩，

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