本文關(guān)鍵詞： Al-Si合金 組織 力學(xué)性能 納米TiC顆粒　出處：《吉林大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：面對環(huán)境和能源的雙重壓力，發(fā)展高性能輕質(zhì)材料已成為現(xiàn)在材料研究的熱點(diǎn)。Al-Si合金具有重量輕、比強(qiáng)度高、良好的導(dǎo)電導(dǎo)熱性能、較高的耐磨性以及較低的熱膨脹系數(shù)等優(yōu)異的綜合性能，使其在汽車制造、航空航天以及機(jī)械制造等領(lǐng)域得到廣泛應(yīng)用。傳統(tǒng)Al-Si二元合金，由于組織中初生硅或共晶硅易引起應(yīng)力集中，且組織中沒有析出強(qiáng)化相，使得Al-Si二元合金的強(qiáng)塑性較低，限制其發(fā)展。近年來，面對高轉(zhuǎn)速大功率發(fā)動機(jī)對其制造材質(zhì)強(qiáng)塑性的要求越來越高，因而Al-Si合金強(qiáng)塑性的提高面臨更大的挑戰(zhàn)。因此，為了進(jìn)一步提高Al-Si合金的室溫、高溫強(qiáng)塑性，，本文以Al-13Si-5Cu-2Ni合金（設(shè)計(jì)成分（wt.%）：Si13.0，Cu5.0，Ni2.0，余量為Al）為研究對象，探索了P變質(zhì)處理和納米TiC顆粒增強(qiáng)對Al-13Si-5Cu-2Ni合金組織與強(qiáng)塑性的影響規(guī)律及機(jī)制。 本文主要研究結(jié)果如下：(1)優(yōu)化出Al-13Si-5Cu-2Ni合金的最佳T6熱處理工藝為：固溶溫度與時間為510℃×8h；時效溫度與時間為165℃×10h。 i)經(jīng)510℃×8h固溶處理，枝晶界處Al2Cu相和部分Al-Cu-Ni相固溶到α-Al基體中，初生硅棱角鈍化，條狀共晶硅熔斷成細(xì)小的共晶硅，但固溶溫度超過510℃會導(dǎo)致合金過燒，固溶時間超過10h會導(dǎo)致共晶硅粗化。 ii)經(jīng)165℃×10h時效處理，θ相的尺寸較小、數(shù)量多、分布均勻，時效硬度最高。165℃時效6h、10h和14h后，θ相的平均直徑長度分別為76.99nm、89.21nm和102.68nm；厚度分別為8.62nm、16.91nm和17.30nm；合金的硬度分別為160HV、164HV、152HV。 iii) Al-13Si-5Cu-2Ni合金經(jīng)510℃×8h固溶，165℃×10h時效，綜合力學(xué)性能最好，拉伸強(qiáng)度為385MPa，斷裂應(yīng)變?yōu)?.0%。 (2)揭示出P變質(zhì)可以同時細(xì)化Al-13Si-5Cu-2Ni合金中初生硅和共晶硅。0.1wt.%P對初生硅變質(zhì)效果最好，初生硅的平均尺寸由未變質(zhì)的24.09μm左右細(xì)化到12.02μm左右；0.005wt.%P對共晶硅的細(xì)化效果最好，共晶硅的平均尺寸由未變質(zhì)的4.16μm左右細(xì)化到為2.55μm左右。 (3)揭示出P變質(zhì)提高Al-13Si-5Cu-2Ni合金的常溫拉伸強(qiáng)度、斷裂應(yīng)變和高溫?cái)嗔褢?yīng)變。 i)0.1wt.%P變質(zhì)合金的常溫拉伸強(qiáng)度和斷裂應(yīng)變均達(dá)到最大，分別為411MPa和8.4%，與未變質(zhì)合金的383MPa和5.8%相比，分別提高了7.3%和44.8%。 ii)0.005wt.%P變質(zhì)合金高溫?cái)嗔褢?yīng)變提高最顯著，由未變質(zhì)合金的8.6%提高到24.4%，提高了近1.8倍。但變質(zhì)合金的高溫拉伸強(qiáng)度與未變質(zhì)合金相比，略有下降。 (4)發(fā)現(xiàn)在納米TiCp/Al-13Si-5Cu-2Ni復(fù)合材料中納米TiCp可以細(xì)化基體合金中的共晶硅、θ析出相和條狀A(yù)l-Cu-Ni相。添加1.0wt.%納米TiCp對共晶硅和θ析出相細(xì)化的綜合效果最好，共晶硅平均尺寸由基體合金的4.16μm左右減小到2.80μm左右；納米θ析出相的平均尺寸由基體合金的直徑約89.21nm左右，厚度約16.91nm左右減小到直徑約64.17nm左右，厚度約13.30nm左右；條狀A(yù)l-Cu-Ni相變成不連續(xù)的顆粒。當(dāng)納米TiCp的添加量超過1.0wt.%時，Si元素的存在會促使部分納米TiCp分解，生成針狀的Al3TiSi相和板條狀Ti-Si-C三元相，復(fù)合材料的拉伸強(qiáng)度開始惡化。 (5)揭示出納米TiCp含量為1.0wt.%時，納米TiCp/Al-13Si-5Cu-2Ni復(fù)合材料的常溫力學(xué)性能最好，拉伸強(qiáng)度和斷裂應(yīng)變分別為408MPa和7.50%，與基體合金相比分別提高了6.5%和29.3%；高溫?cái)嗔褢?yīng)變由基體合金的8.6%提高到10.1%，高溫拉伸強(qiáng)度變化不大。 (6)揭示出納米TiCp/Al-13Si-5Cu-2Ni復(fù)合材料的室溫強(qiáng)化機(jī)制：共晶硅細(xì)化，納米TiCp彌散強(qiáng)化和θ析出相細(xì)化的綜合作用。
[Abstract]:Facing the double pressure of energy and environment, the development of high performance lightweight materials has become a hot research now.Al-Si alloy material has the advantages of light weight, high strength, good electrical and thermal conductivity, excellent comprehensive performance coefficient, high wear resistance and low thermal expansion, which is widely used in automobile manufacturing, aerospace and machinery manufacturing and other fields. The traditional Al-Si two element alloy, due to the organization of primary silicon and eutectic Si can cause stress concentration, and the tissue does not precipitate strengthening phase, the Al-Si two element alloy strength and plasticity is low, limiting its development. In recent years, in the face of high speed high power diesel engine for its manufacturing material strong plasticity of the increasingly high demand, and the Al-Si alloy strong plasticity increase facing greater challenges. Therefore, in order to further improve the Al-Si alloy at room temperature, high temperature and strong plasticity, taking Al-13Si-5Cu-2Ni alloy (Design The composition (wt.%):Si13.0, Cu5.0, Ni2.0, Al as the research object, explored the influence mechanism and mechanism of P modification and nano TiC particle strengthening on the structure and strong plasticity of Al-13Si-5Cu-2Ni alloy.
The main results of this paper are as follows: (1) the best T6 heat treatment process of Al-13Si-5Cu-2Ni alloy is optimized: the solid solution temperature and time are 510 8h, 8h, and the aging temperature and time are 165 c * 10h.
I) is 510 DEG C * 8h solid solution treatment, the dendritic grain boundaries of Al2Cu and Al-Cu-Ni is dissolved into a -Al matrix, the primary silicon edge passivation, eutectic silicon strip eutectic silicon fuse into small, but the solution temperature is higher than 510 DEG C alloy will lead to burning, the solution time will lead to more than 10h the eutectic silicon coarsening.
II) is 165 DEG C * 10h aging treatment, theta phase is small in size, quantity, distribution, limitation of highest hardness ageing 6h.165, 10h and 14h, the average diameter of the length of the theta phase were 76.99nm, 89.21nm and 102.68nm respectively; the thickness of 8.62nm, 16.91nm and 17.30nm; the hardness of the alloy were 160HV 164HV, 152HV..
III) Al-13Si-5Cu-2Ni alloy is solid solution at 510 C by 8h and aging at 165 C for 10h, the best comprehensive mechanical properties, the tensile strength of 385MPa, the fracture strain of 6.0%., are 6.0%..
(2) revealed that the P modification can also refine Al-13Si-5Cu-2Ni alloy in primary silicon and eutectic silicon.0.1wt.%P best on the modification effect of primary silicon, the average size of primary silicon by unmetamorphosed about 24.09 m down to about 12.02 m; the best refinement effect of 0.005wt.%P on eutectic silicon eutectic silicon, the average size of the not bad about 4.16 m down to around 2.55 m.
(3) it is revealed that P metamorphism improves the tensile strength of Al-13Si-5Cu-2Ni alloy at normal temperature, fracture strain and high temperature fracture strain.
The tensile strength and fracture strain of I 0.1wt.%P alloy reached the maximum at room temperature, 411MPa and 8.4% respectively, which increased by 7.3% and 44.8%. compared with 383MPa and 5.8% of unmodified alloy, respectively.
The high temperature fracture strain of II 0.005wt.%P modified alloy increased most significantly from 8.6% of the unmodified alloy to 24.4% and increased by nearly 1.8 times. However, the tensile strength of the modified alloy decreased slightly compared with that of the unmodified alloy.
(4) found in the nano TiCp/Al-13Si-5Cu-2Ni composite nano TiCp eutectic silicon refinement of the matrix alloy, precipitation and strip Al-Cu-Ni. Theta added the comprehensive effect of 1.0wt.% nano TiCp on eutectic silicon and theta precipitates refinement, eutectic silicon alloy matrix by the average size of about 4.16 m reduced to 2.80 m; the average size of nano theta precipitates by matrix alloy with 89.21nm diameter, thickness of about 16.91nm is reduced to a diameter of about 64.17nm or so, the thickness is about 13.30nm; strip Al-Cu-Ni phase becomes discontinuous particles. When the amount of nano TiCp exceeds 1.0wt.%, the presence of a Si element will lead to some nano TiCp decomposition, generate acicular Al3TiSi phase and the lath Ti-Si-C three yuan, the tensile strength of the composites began to deteriorate.
(5) revealed that the nano TiCp content is 1.0wt.%, room temperature mechanical properties of TiCp/Al-13Si-5Cu-2Ni nano composite, tensile strength and fracture strain 408MPa and 7.50% respectively, compared with the matrix alloy were increased by 6.5% and 29.3%; 8.6% increase the fracture strain of the base alloy to 10.1%, high temperature tensile strength changed little.
(6) the room temperature strengthening mechanism of nanoscale TiCp/Al-13Si-5Cu-2Ni composites is revealed: the refinement of eutectic silicon, the dispersion strengthening of nano TiCp and the refinement of the precipitation phase of theta.

【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TG146.21;TB33

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本文編號：1445020