本文選題：鈉 + 鋁銅合金�。� 參考：《山東大學(xué)》2015年碩士論文

【摘要】：鋁及鋁合金在國民經(jīng)濟(jì)和國防建設(shè)各領(lǐng)域中起著相當(dāng)重要的作用。ZL205A是由我國研制并開發(fā)的高強(qiáng)度鑄造鋁合金,其廣泛應(yīng)用于我國的航空航天行業(yè)。對于鋁及其合金制品,含氫量和夾雜物(A1203)等冶金缺陷的存在會直接或間接影響其機(jī)械性能或使用性能。所以,要想獲得高質(zhì)量的產(chǎn)品,必須在澆鑄前想辦法消除這些冶金缺陷,從而提高熔體的純凈度水平。使用精煉劑是提高鋁熔體純凈度水平的有效方法。對于鋁合金的精煉劑,市場上以含鈉精煉劑為主。對于使用ZL205A的軍工企業(yè),他們發(fā)現(xiàn)使用含鈉的精煉劑后對合金的性能造成了不利的影響。為了研究并解決這一工業(yè)問題,我們在本論文中研究了鈉在鋁銅合金中的存在形式和位置以及對合金性能的影響,另外我們還開發(fā)了無鈉精煉劑。本文以含鈉精煉劑為介質(zhì)向鋁銅合金中引入鈉,利用掃描電子顯微鏡(SEM)、探針X射線顯微分析儀(EPMA)、X射線衍射儀(XRD)、高分辨透射電鏡(HRTEM)等分析手段分析了鈉在鋁銅合金中的存在形式以及存在位置。同時也研究了Na的加入對合金產(chǎn)生了哪些不利的影響。本文還配制了多種無鈉精煉劑,然后通過DSC實(shí)驗(yàn)確定各個配方的熔點(diǎn),利用減壓凝固的方法來確定其除氣除雜的效果,最后在生產(chǎn)實(shí)驗(yàn)條件下配合旋轉(zhuǎn)噴吹精煉機(jī)來確定配方是否合適。最終獲得了一種專用于鋁銅合金的無鈉精煉劑。本文的主要研究工作如下：(1)通過熔劑將Na加入到Al-4.5 wt.% Cu合金里。在電子探針顯微鏡(EPMA)下發(fā)現(xiàn)晶界有Na的存在,高分辨透射電鏡(HRTEM)下觀察到了低熔點(diǎn)物質(zhì)的溶解,結(jié)合這兩點(diǎn),推定加入的Na存在于A1-4.5wt.%Cu晶界上,并且是以單質(zhì)鈉呈薄膜態(tài)富集于晶界上。這種Na減弱了a-A1相與CuAl2相之間的結(jié)合力,使得Al-4.5 wt.% Cu合金中的CuAl2相在樣品制作過程中易脫落。(2)加入Na的Al-4.5 wt.% Cu在T6時效后產(chǎn)生裂紋,裂紋處有Na的富集。在T6時效過程中,存在于晶界的單質(zhì)鈉熔化,成為裂紋源,在時效過程中擴(kuò)展生長,最終形成裂紋。在固溶過程中,因?yàn)楸∧拥囊簯B(tài)鈉的存在,使得a-Al相與CuAl2相的互溶速度減慢,這就導(dǎo)致了時效后CuAl2目的殘留。這種殘留的CuAl2相在制樣過程中也易脫落。(3)T6時效后含Na的Al-4.5 wt.% Cu性能急劇下降,斷面的掃描顯微鏡照片顯示,Al-4.5 wt.% Cu的斷裂方式由韌窩斷裂變?yōu)榱搜鼐嗔选?4)所選取的配置精煉劑D的起始熔點(diǎn)為703.9℃,減壓凝固試驗(yàn)后的截面氣孔率低于1%,配合旋轉(zhuǎn)噴吹精煉機(jī)使用后合金性能有所提高。
[Abstract]:Aluminum and aluminum alloys play a very important role in the national economy and national defense construction. ZL205A is a high strength cast aluminum alloy developed by our country. It is widely used in the aerospace industry of our country. For aluminum and its alloy products, the presence of metallurgical defects such as hydrogen content and inclusion A1203 will directly or indirectly affect their mechanical or operational properties. Therefore, in order to obtain high quality products, we must find a way to eliminate these metallurgical defects before casting, so as to improve the purity level of melt. The use of refining agent is an effective method to improve the purity of aluminum melt. For aluminum alloy refining agent, the market mainly contains sodium refining agent. For military companies using ZL205A, they found that the use of sodium-containing refiners adversely affected the properties of the alloy. In order to study and solve this industrial problem, we have studied the form and position of sodium in Al-Cu alloy and its influence on the properties of Al-Cu alloy in this thesis. In addition, we have developed a non-sodium refining agent. In this paper, sodium was introduced into Al-Cu alloy in the medium of refining agent containing sodium. The existence and location of sodium in Al-Cu alloy were analyzed by means of scanning electron microscope (SEM), probe X-ray microanalyzer (EPMA), X-ray diffractometer (XRD) and high resolution transmission electron microscopy (HRTEM). At the same time, the negative effects of Na addition on the alloy were also studied. In this paper, several kinds of sodium free refining agents were prepared, and the melting point of each formula was determined by DSC experiment, and the effect of removing gas and impurity was determined by the method of vacuum solidification. Finally, the formula is determined by rotating injection refining machine under the condition of production experiment. Finally, a sodium-free refining agent for Al-Cu alloy was obtained. The main work of this paper is as follows: 1) adding Na into Al-4.5 wt.% Cu alloy by flux. The presence of Na at grain boundary was observed under EPMA, and the dissolution of low melting point material was observed under high resolution transmission electron microscopy (HRTEM). Combined with these two points, Na was presumed to exist at the grain boundary of A1-4.5wt.%Cu. And it is enriched on grain boundary in the thin film state of sodium. This kind of Na weakens the binding force between a-A1 phase and CuAl2 phase, which makes the CuAl2 phase in Al-4.5 wt.% Cu alloy fall off easily during sample making.) the Al-4.5 wt.% Cu of Na is added into Al-4.5 wt.% Cu to produce cracks after T6 aging, and there is Na enrichment in the crack. During the aging process of T6, the elemental sodium existing at grain boundary melts and becomes the source of crack, which propagates and grows in the aging process, and finally forms the crack. Due to the presence of liquid sodium in the film layer, the intersolubility rate of a-Al phase and CuAl2 phase is slowed down during the solution process, which leads to the residual of CuAl2 after aging. The residual CuAl2 phase is easy to fall off during the preparation of the sample, and the properties of Al-4.5 wt.% Cu containing Na decrease sharply after aging. The scanning microscope photos of the section show that the fracture mode of Al-4.5 wt.% Cu changed from dimple fracture to intergranular fracture. 4) the initial melting point of the modified refining agent D is 703.9 鈩，

本文編號：1971211