本文選題：Al-Fe合金 + 等離子噴注技術��； 參考：《西華大學》2016年碩士論文

【摘要】：本文回顧了Al-Fe合金國內(nèi)外研究現(xiàn)狀,在前人的研究基礎上創(chuàng)新地提出了等離子噴注技術用于制備Al-Fe合金,通過Fe/Al化學體系熱力學及動力學的計算,論證了該方法的理論可行性,并在實驗中得以驗證。針對Fe含量、鋁液溫度、工作電流等實驗參數(shù)的影響進行研究,探索其影響規(guī)律;通過合金化元素Ni的添加以改善Al-Fe合金組織、提高合金性能;進行熱處理實驗,對材料進一步處理,并分析其熱穩(wěn)定性。研究結(jié)果表明,等離子噴注法利用原位反應生成Al_3Fe合金相,Al_3Fe存在著多邊形與細針狀兩種形態(tài),多邊形Al_3Fe由Fe粉與鋁液原位反應生成,細針狀Al_3Fe由溶解的Fe在凝固時析出生成。Al_3Fe在合金中的體積分數(shù)與Fe含量直接相關,Fe含量越高,Al_3Fe體積分數(shù)越高,同時使得合金密度、硬度、抗拉強度上升,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較易產(chǎn)生氣孔。鋁液溫度對合金組織及力學性能有較大的影響,鋁液溫度越高,Al_3Fe越粗大、且越易趨向長針狀生長,從而導致合金力學性能嚴重下降,對于Al-10%Fe合金,鋁液溫度在800℃以下時,Al_3Fe顆粒尺寸較小,合金性能較好。工作電流在球化、加熱、加速Fe粉方面有有益效果,能促進Fe粉與鋁液的反應,但工作電流過高時,將導致Fe粉與鋁液的實際反應溫度過高,從而增加Al_3Fe長針狀的趨勢,對于Al-10%Fe合金,工作電流在200A~300A之間時較為適宜。Ni元素對于改善合金組織、提高合金性能上有不錯的效果。研究發(fā)現(xiàn),Ni的加入將生成Al_9FeNi,從而抑制細針狀Al_3Fe的生成并減少多邊形Al_3Fe的尖角部分、細化多邊形Al_3Fe顆粒。分析認為,Ni元素的細化機理在于其將與部分溶解于鋁液中的Fe一同析出,由于Ni元素占據(jù)了Fe的位置,使得Al_3Fe的針狀生長方式受阻,因此,Al_3Fe來不及長成針狀便凝固下來,從而生成細顆粒態(tài)Al_3Fe。但過多的Ni含量將導致Al_9FeNi組織變?yōu)榇执?對于Al-10%Fe合金,Ni元素含量最好控制在2%以下。均勻化退火能減少細針狀Al_3Fe的含量,在提升Al-Fe合金延伸率上有不錯的效果,但會引起合金力學性能的輕微下降,下降原因與合金晶粒的長大有一定的聯(lián)系。熱穩(wěn)定性實驗表明,Al-Fe合金有著較強的熱穩(wěn)定性,材料經(jīng)640℃的長時間高溫退火后,Al_3Fe長大的幅度依然較小,并未呈長針狀生長,并且Ni元素的加入能進一步提高材料的熱穩(wěn)定性,這與Ni元素形成的細小彌散相有一定的關系。
[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，

本文編號：2078184