Al-13Si-5Cu-2Ni合金及其复合材料的组织与力学性能

发布时间：2018-01-19 18:28

本文关键词： Al-Si合金组织力学性能纳米TiC颗粒　出处：《吉林大学》2015年硕士论文　论文类型：学位论文

【摘要】：面对环境和能源的双重压力，发展高性能轻质材料已成为现在材料研究的热点。Al-Si合金具有重量轻、比强度高、良好的导电导热性能、较高的耐磨性以及较低的热膨胀系数等优异的综合性能，使其在汽车制造、航空航天以及机械制造等领域得到广泛应用。传统Al-Si二元合金，由于组织中初生硅或共晶硅易引起应力集中，且组织中没有析出强化相，使得Al-Si二元合金的强塑性较低，限制其发展。近年来，面对高转速大功率发动机对其制造材质强塑性的要求越来越高，因而Al-Si合金强塑性的提高面临更大的挑战。因此，为了进一步提高Al-Si合金的室温、高温强塑性，，本文以Al-13Si-5Cu-2Ni合金（设计成分（wt.%）：Si13.0，Cu5.0，Ni2.0，余量为Al）为研究对象，探索了P变质处理和纳米TiC颗粒增强对Al-13Si-5Cu-2Ni合金组织与强塑性的影响规律及机制。本文主要研究结果如下：(1)优化出Al-13Si-5Cu-2Ni合金的最佳T6热处理工艺为：固溶温度与时间为510℃×8h；时效温度与时间为165℃×10h。 i)经510℃×8h固溶处理，枝晶界处Al2Cu相和部分Al-Cu-Ni相固溶到α-Al基体中，初生硅棱角钝化，条状共晶硅熔断成细小的共晶硅，但固溶温度超过510℃会导致合金过烧，固溶时间超过10h会导致共晶硅粗化。 ii)经165℃×10h时效处理，θ相的尺寸较小、数量多、分布均匀，时效硬度最高。165℃时效6h、10h和14h后，θ相的平均直径长度分别为76.99nm、89.21nm和102.68nm；厚度分别为8.62nm、16.91nm和17.30nm；合金的硬度分别为160HV、164HV、152HV。 iii) Al-13Si-5Cu-2Ni合金经510℃×8h固溶，165℃×10h时效，综合力学性能最好，拉伸强度为385MPa，断裂应变为6.0%。 (2)揭示出P变质可以同时细化Al-13Si-5Cu-2Ni合金中初生硅和共晶硅。0.1wt.%P对初生硅变质效果最好，初生硅的平均尺寸由未变质的24.09μm左右细化到12.02μm左右；0.005wt.%P对共晶硅的细化效果最好，共晶硅的平均尺寸由未变质的4.16μm左右细化到为2.55μm左右。 (3)揭示出P变质提高Al-13Si-5Cu-2Ni合金的常温拉伸强度、断裂应变和高温断裂应变。 i)0.1wt.%P变质合金的常温拉伸强度和断裂应变均达到最大，分别为411MPa和8.4%，与未变质合金的383MPa和5.8%相比，分别提高了7.3%和44.8%。 ii)0.005wt.%P变质合金高温断裂应变提高最显著，由未变质合金的8.6%提高到24.4%，提高了近1.8倍。但变质合金的高温拉伸强度与未变质合金相比，略有下降。 (4)发现在纳米TiCp/Al-13Si-5Cu-2Ni复合材料中纳米TiCp可以细化基体合金中的共晶硅、θ析出相和条状Al-Cu-Ni相。添加1.0wt.%纳米TiCp对共晶硅和θ析出相细化的综合效果最好，共晶硅平均尺寸由基体合金的4.16μm左右减小到2.80μm左右；纳米θ析出相的平均尺寸由基体合金的直径约89.21nm左右，厚度约16.91nm左右减小到直径约64.17nm左右，厚度约13.30nm左右；条状Al-Cu-Ni相变成不连续的颗粒。当纳米TiCp的添加量超过1.0wt.%时，Si元素的存在会促使部分纳米TiCp分解，生成针状的Al3TiSi相和板条状Ti-Si-C三元相，复合材料的拉伸强度开始恶化。 (5)揭示出纳米TiCp含量为1.0wt.%时，纳米TiCp/Al-13Si-5Cu-2Ni复合材料的常温力学性能最好，拉伸强度和断裂应变分别为408MPa和7.50%，与基体合金相比分别提高了6.5%和29.3%；高温断裂应变由基体合金的8.6%提高到10.1%，高温拉伸强度变化不大。 (6)揭示出纳米TiCp/Al-13Si-5Cu-2Ni复合材料的室温强化机制：共晶硅细化，纳米TiCp弥散强化和θ析出相细化的综合作用。
[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.

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG146.21;TB33

【参考文献】