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随着电子通信等行业的快速发展, 对高导热铸造铝合金材料性能要求日益增加. 本文以在电子通信等行业广泛使用的Al-7Si(质量分数, 下同)铸造铝合金为对象, 系统分析了热处理工艺制度以及少量的Mg元素添加对Al-7Si系合金微观组织及性能的影响. 结果表明: 固溶后在300 ℃下进行保温热处理有利于共晶Si的球化, 并减小溶质原子在铝基体中的固溶度, 从而导致Al-7Si合金导热性能的提升及硬度的降低; 在Al-7Si合金中添加微量Mg(0.4%)后进行三级热处理(固溶处理+300 ℃热处理+180 ℃热处理)不仅有助于共晶Si的球化, 而且能促使纳米尺度(Mg, Si)强化相的析出以及基体中固溶的Mg, Si元素含量的降低, 从而同时提高合金的力学性能和导热性能. 经历三级热处理的Al-7Si-0.4Mg合金热导率和显微硬度可达189 W/(m·K)和73.5 HV, 相较于铸态Al-Si合金分别提升了11.2%和62.6%.
Al-Si alloys have been widely used in automotive, aerospace, electronics and communication industries due to their excellent castability, low thermal expansion, and good wear and corrosion resistance. However, the presence of coarse eutectic Si often results in relatively low thermal conductivity. With the rapid development of the electronics and communication industries, the requirements for thermal conductivity and mechanical properties of materials are increasing. In this study, the effects of heat treatment and minor Mg addition on the microstructure, mechanical properties, and thermal conductivity of Al-7Si alloys are systematically investigated. The results indicate that heat treatment at 300 ℃ after solution treatment promotes the spheroidization of eutectic Si and reduces the solid solubility of solute atoms in the aluminum matrix, thereby enhancing the thermal conductivity and reducing the hardness of the Al-7Si alloy. The three-step heat treatment process (solution treatment +300 ℃ treatment +180 ℃ treatment) not only facilitates the spheroidization of eutectic Si, but also induces the precipitation of nanoscale (Mg, Si) strengthening phases, further reducing the solid solubility of solute elements in the Al-7Si alloy with 0.4%Mg addition. After the three-step heat treatment, the Al-7Si-0.4Mg alloy reaches to 189 W/(m·K) in thermal conductivity and 73.5 HV in microhardness, respectively, which are increased by 11.2% and 62.6% respectively, compared with the as-cast Al-7Si alloy. According to the Wiedemann-Franz law and the Matthiessen-Fleming rule, the primary factors influencing the thermal conductivity of alloys are solute atoms in solid solution and secondary phases. In this study, a three-step heat treatment process is used to transform the plate-like eutectic silicon in the Al-7Si-0.4Mg alloy into fine spherical particles. Additionally, micrometer-sized silicon particles and nanoscale (Mg, Si) precipitates are induced within the alloy matrix. This microstructural modification simultaneously enhances the thermal conductivity and mechanical properties of the alloy. Our work is expected to inspire the design of Al-Si alloy with high strength and high conductivity. -
Keywords:
- Al-Si alloy /
- microstructure /
- thermal conductivity /
- mechanical property
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图 1 铸态Al-7Si合金的二次电子图像和能谱元素分布 (a) 二次电子图像; (b) 铝; (c) 硅; (d) 铁; (e) 镧; (f) 锶
Fig. 1. Secondary electron imaging and energy dispersive spectroscopy elemental distribution of as-cast Al-7Si alloy: (a) SEI; (b) Al; (c) Si; (d) Fe; (e) La; (f) Sr.
图 2 Al-7Si合金的SEM图像 (a) 铸态; (b) 530 ℃固溶1 h; (c) 530 ℃固溶2 h; (d) 铸态, 300 ℃保温80 min; (e) 530 ℃固溶1 h后, 300 ℃保温80 min; (f) 530 ℃固溶2 h后, 300 ℃保温80 min
Fig. 2. SEM images of the Al-7Si alloy: (a) As-cast; (b) after solution treatment at 530 ℃ for 1 hour; (c) after solution treatment at 530 ℃ for 2 hours; (d) as-cast, then held at 300 ℃ for 80 minutes; (e) after solution treatment at 530 ℃ for 1 hour followed by holding at 300 ℃ for 80 minutes; (f) after solution treatment at 530 ℃ for 2 hours followed by holding at 300 ℃ for 80 minutes.
图 3 Al-7Si合金在300 ℃下保温80 min的二次电子图像和能谱元素分布 (a), (d) 二次电子图像; (b), (e) 铝; (c), (f) 硅
Fig. 3. Secondary electron imaging and energy dispersive spectroscopy elemental distribution of Al-7Si alloy at 300 ℃ for 80 minutes: (a), (d) SEI; (b), (e) Al; (c), (f) Si.
图 4 Al-7Si合金热处理过程中热导率及硬度随时间的变化 (a) 固溶过程中的热导率变化; (b) 300 ℃保温热处理过程中的热导率变化; (c) 固溶过程中的硬度变化; (d) 300 ℃保温热处理过程中的硬度变化
Fig. 4. Variations in thermal conductivity and hardness of Al-7Si alloy during heat treatment as a function of time: (a) Thermal conductivity variation during solution treatment; (b) thermal conductivity variation during 300 ℃ isothermal heat treatment; (c) hardness variation during solution treatment; (d) hardness variation during 300 ℃ isothermal heat treatment.
图 5 铸态Al-7Si-0.4Mg合金的二次电子图像和能谱元素分布 (a) 二次电子图像; (b) 铝; (c) 硅; (d) 铁; (e) 镧; (f) 锶; (g) 镁
Fig. 5. Secondary electron imaging and energy dispersive spectroscopy elemental distribution of as-cast Al-7Si-0.4Mg alloy: (a) SEI; (b) Al; (c) Si; (d) Fe; (e) La; (f) Sr; (g) Mg.
图 6 Al-7Si-0.4Mg合金的SEM图像 (a) 铸态; (b) 530 ℃固溶1 h; (c) 530 ℃固溶2 h; (d) 铸态, 300 ℃保温80 min; (e) 530 ℃固溶1 h后, 300℃保温80 min; (f) 530 ℃固溶2 h后, 300 ℃保温80 min
Fig. 6. SEM images of the Al-7Si-0.4Mg alloy: (a) As-cast; (b) after solution treatment at 530 ℃ for 1 hour; (c) after solution treatment at 530 ℃ for 2 hours; (d) as-cast, then held at 300 ℃ for 80 minutes; (e) after solution treatment at 530 ℃ for 1 hour followed by holding at 300 ℃ for 80 minutes; (f) after solution treatment at 530 ℃ for 2 hours followed by holding at 300 ℃ for 80 minutes.
图 7 Al-7Si-0.4Mg合金热处理过程中热导率及硬度随时间的变化 (a) 固溶过程中的热导率变化; (b) 高温保温热处理过程中的热导率变化; (c) 固溶过程中的硬度变化; (d) 高温保温热处理过程中的硬度变化
Fig. 7. Variations in thermal conductivity and hardness of Al-7Si-0.4Mg alloy during heat treatment as a function of time: (a) Thermal conductivity variation during solution treatment; (b) thermal conductivity variation during high-temperature isothermal heat treatment; (c) hardness variation during solution treatment; (d) hardness variation during high-temperature isothermal heat treatment.
图 8 不同热处理工艺后的Al-7Si-0.4Mg合金的室温拉伸性能
Fig. 8. Mechanical properties at room temperature of Al-7Si-0.4Mg alloy after different heat treatment processes.
图 9 经历不同热处理后Al-7Si-0.4Mg合金的TEM分析结果 (a) 双级热处理(530 ℃固溶1.5 h+300 ℃保温60 min)样品的明场像及Mg, Si元素分布; (b) 三级热处理(530 ℃固溶1.5 h+300 ℃保温60 min+180 ℃×6 h)样品的明场像及Mg, Si元素分布; (c) β'' 及β' 相的高分辨图像及傅里叶变换花样
Fig. 9. Representative TEM images of Al-7Si-0.4Mg alloy after different heat treatments: (a) Bright-field images, Mg element distribution and Si element distribution of the double-step heat treatment samples (solution at 530 ℃ for 1.5 h+holding at 300 ℃ for 60 min); (b) bright-field image, Mg element distribution, Si element distribution of the triple-step heat treatment samples (530 ℃×1.5 h solution +300 ℃×60 min+180 ℃×6 h); (c) high resolution TEM images and corresponding FFT images of β'' and β' phase.
表 1 实验合金的化学成分(质量分数)(单位: %)
Table 1. Chemical compositions (weight percent) of the experimental alloys (Unit: %).
Alloy Mg B La Sr Fe Si Al Al-7Si 0 0.024 0.04 0.02 0.25 7 Bal. Al-7Si-0.4Mg 0.4 0.024 0.04 0.02 0.25 7 Bal. 
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表 2 Al-7Si和Al-7Si-0.4Mg合金的热处理工艺参数
Table 2. Heat treatment process parameters for the Al-7Si and Al-7Si-0.4Mg alloys
Alloy Process Temperature/℃ Time Al-7Si SS 530 0 h, 0.5 h, 1 h, 1.5 h, 2 h HT 300 0 min, 20 min, 40 min,
60 min, 80 min, 100 minAl-7Si-
0.4MgSS 530 0 h, 0.5 h, 1 h, 1.5 h, 2 h HT 300 0 min, 20 min, 40 min,
60 min, 80 min, 100 minLT 180 0 h, 6 h, 12 h
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表 3 Al-7Si-0.4Mg试样的热处理工艺及性能
Table 3. Heat treatment process and properties of the Al-7Si-0.4Mg samples.
Heat treatment process Thermal conductivity
/(W·m–1·K–1)Hardness
/HVUltra tensile stress/MPa Elongation/% As-cast 162 60.9 169 6.25 SS1.5 h+HT60 min 185 62.9 176 8 SS1.5 h+HT60 min+LT6 h 183 79.5 206 6 SS1.5 h+HT60 min+LT12 h 189 73.5 186 5.75
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[1] 刘静安, 谢水生 2004 铝合金材料的应用与技术开发 (北京: 冶金工业出版社) 第139页
Liu J A, Xie S S 2004 Application and Technical Development of Aluminum Alloy Materials (Beijing: Metallurgical Industry Press) p139
[2] Zhang J X, Zhang M J, Li H F, Gu H Z, Chen D, Zhang C H, Tian Y F, Wang E J, Mu Q N 2024 J. Mater. Sci. Technol. 176 48
Google Scholar
[3] 高学鹏, 李新涛, 郄喜望, 吴亚萍, 李喜孟, 李廷举 2007 物理学报 56 1188
Google Scholar
Gao X P, Li X T, Qie X W, Wu Y P, Li X M, Li T J 2007 Acta Phys. Sin. 56 1188
Google Scholar
[4] Zhao Z Y, Li D X, Yan X R, Chen Y, Jia Z, Zhang D Q, Han M X, Wang X, Liu G L, Liu X F, Liu S D 2024 J. Mater. Sci. Technol. 189 44
Google Scholar
[5] 张瑞英, 李继承, 沙君浩, 李家康 2024 材料热处理学报 45 53
Google Scholar
Zhang R Y, Li J C, Sha J H, Li J K 2024 Trans. Mater. Heat Treat. 45 53
Google Scholar
[6] Gan J Q, Huang Y J, Du J, Wen C, Liu J 2020 Mater. Res. Express 7 086501
Google Scholar
[7] 张丽丽, 吉宗威, 赵九洲, 何杰, 江鸿翔 2023 金属学报 59 1541
Google Scholar
Zhang L L, Ji Z W, Zhao J Z, He J, Jiang H X 2023 Acta Metall. Sin. 59 1541
Google Scholar
[8] 郑秋菊, 叶中飞, 江鸿翔, 卢明, 张丽丽, 赵九洲 2021 金属学报 57 103
Google Scholar
Zheng Q J, Ye Z F, Jiang H X, Lu M, Zhang L L, Zhao J Z 2021 Acta Metall. Sin. 57 103
Google Scholar
[9] Zheng Q J, Zhang L L, Jiang H X, Zhao J Z, He J 2020 J. Mater. Sci. Technol. 47 142
Google Scholar
[10] 戚忠乙, 王博, 江鸿翔, 张丽丽, 何杰 2024 物理学报 73 076401
Google Scholar
Qi Z Y, Wang B, Jiang H X, Zhang L L, He J 2024 Acta Phys. Sin. 73 076401
Google Scholar
[11] Dong X X, He L J, Li P J 2014 J. Alloys Compd. 612 20
Google Scholar
[12] Chen Z W, Lei Y M, Zhang H F. 2011 J. Alloys Compd. 509 27
Google Scholar
[13] Zhan M Y, Chen Z H, Yan H G 2008 J. Mater. Process. Technol. 202 269
Google Scholar
[14] Taghavi F, Saghafian H, Kharrazi Y H K 2009 Mater. Des. 30 115
Google Scholar
[15] 毛卫民, 赵爱民, 崔成林, 钟雪友 1999 金属学报 35 971
Google Scholar
Mao W M, Zhao W M, Cui C L, Zhong X Y 1999 Acta Metall. Sin. 35 971
Google Scholar
[16] Jin C K, Bolouri A, Kang C G 2014 Metall. Mater. Trans. B 45 1068
Google Scholar
[17] Wang J Y, Wang B J, Huang L F 2017 J. Mater. Sci. Technol. 33 1235
Google Scholar
[18] Cheng W, Liu C Y, Huang H F, Zhang L, Zhang B, Shi L 2021 Mater. Charact. 178 111278
Google Scholar
[19] Torres L V, Zoqui E J 2024 Int. J. Metalcast. 18 769
Google Scholar
[20] Son H W, Lee J Y, Cho Y H, Jang J I, Kim S B, Lee J M 2023 J. Alloys Compd. 960 170982
Google Scholar
[21] 刘启阳, 李庆春, 朱培钺 1987 金属科学与工艺 6 65
Liu Q Y, Li Q C, Zhu P Y 1987 Met. Sci. Technol. 6 65
[22] Bakhtiyarov S I, Overfelt R A, Teodorescu S G 2001 J. Mater. Sci. 36 4643
Google Scholar
[23] 王奥, 盛宇飞, 鲍华 2024 物理学报 73 037201
Google Scholar
Wang A, Sheng Y F, Bao H 2024 Acta Phys. Sin. 73 037201
Google Scholar
[24] Hou J P, Wang Q, Zhang Z J, Tian Y Z, Wu X M, Yang H J, Li X W, Zhang Z F 2017 Mater. Des. 132 148
Google Scholar
[25] Wang W Y, Pan Q L, Jiang F Q, Yu Y, Lin G, Wang X D, Ye J, Pan D C, Huang Z Q, Xiang S Q, Li J, Liu B 2022 J. Alloys Compd. 895 162654
Google Scholar
[26] Zhang J Y, Peng J 2023 J. Mater. Res. 38 1488
Google Scholar
[27] Raeisinia B, Poole W J, Lloyd D J 2006 Mater. Sci. Eng. , A 420 245
Google Scholar
[28] Chen J K, Hung H Y, Wang C F, Tang N K 2015 J. Mater. Sci. 50 5630
Google Scholar
[29] Weng W P, Nagaumi H, Sheng X D, Fan W Z, Chen X C, Wang X N 2019 Light Metals Symposium at the 148th TMS Annual Meeting San Antonio, TX, March 10–12, 2019 p193
[30] 李双寿, 唐靖林, 曾大本 2008 特种铸造及有色合金 0117 04
Li S S, Tang J L, Zeng D B 2008 Spec. Cast. Nonferrous Alloys 0117 04
[31] Sauvage X, Bobruk E V, Murashkin M Y, Nasedkina Y, Enikeev N A, Valiev R Z 2015 Acta Mater. 98 355
Google Scholar
[32] 李小松, 蔡安辉, 陈华, 曾纪杰 2009 热加工工艺 38 117
Google Scholar
Li X S, Cai A H, Chen H, Zeng J J 2009 Hot Work. Technol. 38 117
Google Scholar
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