本文選題：Al-Si合金 + Al-Mn合金��； 參考：《濟(jì)南大學(xué)》2016年碩士論文

【摘要】：鋁合金在工業(yè)上的大范圍使用雖然較晚,但已發(fā)展成為除鋼鐵外的第二大金屬材料,其發(fā)展速度可見一斑。在汽車的輕量化方面,鋁合金的應(yīng)用起著很大作用,利用鑄造鋁合金代替原有的鋼鐵材料,不僅可以減輕汽車的總體質(zhì)量,還可以節(jié)省能耗,減少污染。在變形鋁合金方面,鋁板、鋁帶、鋁管等鋁材料也廣泛應(yīng)用在建筑、包裝、機(jī)械等方面。目前,由于鋁合金的強(qiáng)度較低,嚴(yán)重限制了其發(fā)展,因此,開發(fā)出新成分、新工藝的高強(qiáng)度鋁合金已成為目前研究的重中之重。本論文一部分以鑄造Al-Si合金為對(duì)象,研究可提高其強(qiáng)度的強(qiáng)化手段;另一部分依據(jù)“高性能鋁單板材料的研制”項(xiàng)目,研究可提高Al-Mn合金強(qiáng)度,并保持其良好塑性的強(qiáng)化手段。本文利用拉伸試驗(yàn)、金相顯微鏡、偏光顯微鏡、掃描電鏡及能譜分析、X射線衍射、電化學(xué)腐蝕、熱分析等手段來研究合金化、細(xì)化變質(zhì)、熱速處理以及熔體復(fù)合處理對(duì)Al-Si及Al-Mn合金的影響。確定Al-Si合金基體成分為:Al-9Si-0.5Mg。利用差示掃描量熱分析(DSC),發(fā)現(xiàn)合金在855~885℃范圍出現(xiàn)熔體結(jié)構(gòu)轉(zhuǎn)變。根據(jù)此溫度范圍確定Al-9Si-0.5Mg合金的熱速處理溫度為830℃~990℃。實(shí)驗(yàn)結(jié)果表明,隨著熱速處理時(shí)熔體溫度的改變,合金的力學(xué)性能及微觀組織也發(fā)生改變。當(dāng)合金熔體溫度達(dá)到930℃并保溫20min后,加入冷料時(shí)熔體溫度快速降到澆注溫度(760℃)并保溫10min時(shí),合金的力學(xué)性能達(dá)到最好,它的抗拉強(qiáng)度、屈服強(qiáng)度、硬度以及伸長(zhǎng)率與常規(guī)熔煉工藝下相比分別提高了24.3%、37.7%、82.9%、21.8%。合金的中α-Al晶粒由粗大的枝晶轉(zhuǎn)變?yōu)橹鶢罨虻容S狀晶粒,共晶Si則由長(zhǎng)針狀轉(zhuǎn)變?yōu)轭w粒狀,可見熱速處理可使合金的微觀組織得到明顯細(xì)化。在Al-9Si-0.5Mg合金中加入稀土Y也可使合金的力學(xué)性能得到一定提高,在加入0.2%Y后,合金的抗拉強(qiáng)度、屈服強(qiáng)度、伸長(zhǎng)率、硬度均達(dá)到最大值,比未添加Y時(shí)分別提高了12.8%、17.2%、31.9%、9.6%。Y在加入合金后會(huì)吸附在Si生長(zhǎng)臺(tái)階上,改變Si的生長(zhǎng)方式,使共晶Si轉(zhuǎn)變?yōu)轭w粒狀。此外,加入Y后,還可以提高合金的耐腐蝕性。通過對(duì)新制備出的Al-3Ti-3B-1Y中間合金進(jìn)行XRD、SEM、EDS分析可知在Al-3Ti-3B-1Y中存在著TiB_2、AlB2、TiA_l3和Ti4Al43Y6相,作為中間合金加入到Al-Si合金中后,各相所起到的形核作用其機(jī)理略有不同。當(dāng)加入3%Al-3Ti-3B-1Y后,合金的晶粒得到明顯細(xì)化,α-Al由于形核核心的增多所生成的晶粒也較細(xì)小,共晶Si同樣轉(zhuǎn)變?yōu)轭w粒狀,同時(shí)合金的力學(xué)性能得到提高,其抗拉強(qiáng)度提高了19.3%;屈服強(qiáng)度提高了28.3%;伸長(zhǎng)率提高了65.1%;硬度提高了20.5%。熱速處理可從工藝上改善Al-Si合金性能,細(xì)化變質(zhì)處理通過加入外加形核劑來改善Al-Si合金性能,因此將兩者復(fù)合,即采用熔體復(fù)合處理的方法來強(qiáng)化Al-Si合金。實(shí)驗(yàn)結(jié)果表明,最佳的熔體復(fù)合處理工藝為:首先對(duì)Al-9Si-0.5Mg合金在熔體溫度為930℃時(shí)進(jìn)行熱速處理,待合金溫度降到澆注溫度760℃時(shí),加入3%Al-3Ti-3B-1Y中間合金,保溫后澆注。通過對(duì)不同強(qiáng)化方式的綜合比較后發(fā)現(xiàn),合金在經(jīng)過熔體復(fù)合處理后,其綜合力學(xué)性能最佳。此時(shí),Al-9Si-0.5Mg合金的抗拉強(qiáng)度、屈服強(qiáng)度、硬度、伸長(zhǎng)率與未處理的合金相比分別提高了31.2%、22.6%、25.6%和80.5%。α-Al晶粒與共晶Si也得到了較好的細(xì)化。在Al-1.2Mn合金中加入稀土Y以及Al-5Ti-1B中間合金都可使Al-1.2Mn合金的晶粒得到不同給程度的細(xì)化,尤其是加入Al-5Ti-1B中間合金后,Al-1.2Mn的晶粒由粗大枝晶轉(zhuǎn)變?yōu)槌叽巛^小的等軸狀晶粒,合金中第二相粒子也變小,形貌改變,粗大骨骼狀第二相減少。同時(shí)Al-1.2Mn的強(qiáng)度得到稍許提升,但伸長(zhǎng)率提高較大,合金塑性較好。在加入Mg、Si后,Al-1.2Mn合金的強(qiáng)度提高幅度很大,但伸長(zhǎng)率急劇降低,合金的塑性變差。當(dāng)Si加入量較高時(shí),會(huì)與Fe形成骨骼狀α-Al12(FeMn)3Si相,影響合金性能,必須嚴(yán)格控制Mg、Si加入量。為提高合金的塑性,在Mg、Si強(qiáng)化后的Al-1.2Mn合金中加入Al-5Ti-1B中間合金后,合金的強(qiáng)度繼續(xù)提高,伸長(zhǎng)率略有降低,但仍可保持在20%以上,此時(shí)制備出的合金在具有高強(qiáng)度的同時(shí)保持了良好的塑性。Mg、Si及Al-5Ti-1B的最佳加入量分別為0.5%、0.3%和2%,此時(shí)合金的抗拉強(qiáng)度達(dá)到156MPa、屈服強(qiáng)度達(dá)到64MPa、硬度達(dá)到了52HB,分別提高了35.6%、28.1%、40.5%,而伸長(zhǎng)率達(dá)到21.5%,各項(xiàng)力學(xué)性能指標(biāo)均達(dá)到所需要求。這主要是由于在加入Al-5Ti-1B后,其中的TiA_l3和TiB_2粒子為合金晶粒提高了大量的形核質(zhì)點(diǎn)。
[Abstract]:Aluminum alloy has been developed into second big metal materials except iron and steel, although it has been used in a large range of industry, its development speed can be seen. The application of aluminum alloy plays a great role in the light weight of the automobile. The use of cast aluminum alloy instead of the original steel material can not only reduce the overall quality of the automobile, but also can be used to reduce the overall quality of the automobile. In the deformed aluminum alloy, aluminum, aluminum, aluminum and other aluminum materials are widely used in construction, packaging, machinery and other aspects. At present, because of the low strength of the aluminum alloy, the development of aluminum alloy is seriously restricted. Therefore, the development of new components and new technology of high strength aluminum alloy has become the top priority of the present research. Some methods of strengthening the strength of the cast Al-Si alloy are studied. The other is based on the development of the high performance aluminum sheet material. The strength of Al-Mn alloy can be improved and its good plasticity is maintained. In this paper, the tensile test, metallographic microscope, polarizing microscope, scanning electron microscope and energy spectrum analysis, X The effects of alloying, refinement, heat speed treatment and melt composite treatment on Al-Si and Al-Mn alloys were studied by ray diffraction, electrochemical corrosion and thermal analysis. The matrix composition of Al-Si alloy was determined by Al-9Si-0.5Mg. using differential scanning calorimetry (DSC), and the melt structure transition at 855~885 C was found. The thermal speed treatment temperature of Al-9Si-0.5Mg alloy is 830 C ~990 C. The results show that the mechanical properties and microstructure of the alloy also change with the change of the melt temperature during the heat treatment. When the melt temperature reaches 930 C and 20min, the melt temperature drops to the pouring temperature (760 degrees C) when the cold material is added. The tensile strength, yield strength, hardness and elongation of the alloy increased by 24.3%, 37.7%, 82.9%, respectively, while the tensile strength, yield strength, hardness and elongation of the alloy increased by 24.3%, 37.7%, 82.9%. The eutectic Si was transformed from a long needle to granular, and the eutectic Si was transformed from a long needle to granular, and the heat was visible. With the addition of rare earth Y in Al-9Si-0.5Mg alloy, the mechanical properties of the alloy can be improved. After adding 0.2%Y, the tensile strength, yield strength, elongation and hardness of the alloy reached the maximum, which increased by 12.8%, 17.2%, 31.9%, respectively, when the alloy was added to the alloy, and 9.6%.Y was added to the alloy. Then it will adsorb on the Si growth step, change the growth mode of Si and change the eutectic Si into granular. In addition, after adding Y, the corrosion resistance of the alloy can be improved. By the XRD, SEM, EDS analysis of the newly prepared Al-3Ti-3B-1Y intermediate alloy, TiB_2, AlB2, TiA_l3, and facies are found in Al-3Ti-3B-1Y as intermediate alloy. After adding to Al-Si alloy, the mechanism of nucleation of each phase is slightly different. When 3%Al-3Ti-3B-1Y is added, the grain of the alloy is obviously refined, and the grain of alpha -Al is smaller because of the increase of nucleation core, and the eutectic Si is also transformed into granular, and the mechanical properties of the alloy are improved and the tensile strength of the alloy is improved. The yield strength was 19.3%, the yield strength increased by 28.3%, the elongation increased by 65.1%, and the hardness improved 20.5%. heat speed treatment can improve the properties of Al-Si alloy from the process, refining the modification treatment by adding external nucleating agent to improve the performance of Al-Si alloy. Therefore, the combination of the two, that is, the method of melt composite treatment to strengthen the Al-Si alloy. The optimum melt treatment process is as follows: first, the Al-9Si-0.5Mg alloy is treated by heat treatment at the melt temperature of 930 C. When the temperature of the alloy is reduced to the pouring temperature of 760 C, the 3%Al-3Ti-3B-1Y intermediate alloy is added to the alloy to be cast after heat preservation. After the comprehensive comparison of the different strengthening methods, it is found that the alloy is treated after the melt compound treatment. At this time, the tensile strength, yield strength, hardness and elongation of Al-9Si-0.5Mg alloy increased by 31.2%, 22.6%, 25.6% and 80.5%. alpha -Al grain and eutectic Si, respectively. The addition of Y and Al-5Ti-1B intermediate alloy to Al-1.2Mn alloy can make Al-1.2Mn alloy. After adding Al-5Ti-1B intermediate alloy, the grain of Al-1.2Mn is changed from coarse dendrite to smaller size, and the second phase particles in the alloy also become smaller, the morphology changes, and the second phase of the coarse skeleton decreases. At the same time, the strength of the Al-1.2Mn is slightly enhanced, but the elongation increases greatly. The strength of gold is better. After adding Mg and Si, the strength of Al-1.2Mn alloy is greatly increased, but the elongation of the alloy decreases sharply and the plasticity of the alloy becomes worse. When the amount of Si is high, it will form a skeletal alpha -Al12 (FeMn) 3Si phase with Fe, which affects the alloy properties. It is necessary to strictly control the Mg and Si addition. After adding Al-5Ti-1B intermediate alloy in gold, the strength of the alloy continues to increase and the elongation is slightly lower, but it can still remain above 20%. At this time, the alloy has a good plastic.Mg while the best addition of Si and Al-5Ti-1B is 0.5%, 0.3% and 2% respectively. The tensile strength of the alloy reaches 156MPa, and the yield is strong. The degree of hardness reached 64MPa, the hardness reached 52HB, increased by 35.6%, 28.1%, 40.5% respectively, and the elongation reached 21.5%. All the mechanical properties reached the required requirements. This was mainly due to the increase of TiA_l3 and TiB_2 particles in the alloy after the addition of Al-5Ti-1B, which increased a large number of nucleation particles.

【學(xué)位授予單位】：濟(jì)南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TG146.21

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