过共晶铝硅合金由于结合了铝和硅各自的优点，可以在适用范围内可调节的热膨胀性以及良好的机加工性能等，使得其成为航空、航天、电子封装领域的研究热点。本文选用 的Al-50wt.%Si合金粉末，使用放电等离子烧结制备合金材料，通过改变烧结参数，研究了所制合金的显微组织、物相组成以及力学性能以及致密度等。并通过理论分析，结合实测值，探究了合金应用于电子封装材料的热导率，热膨胀系数的改变机理。

(1) 通过对合金粉末分析，粉末的球形度达到99.6%。同时，粉末的流动性测量值为10.40s/50g。粉末的颗粒尺寸维持在 左右，外表面光滑，呈现规则球形且无明显孔洞。粉末侧切图显示，粉末内部的Si由块状的初生硅和细小的网格状共晶硅组成，初生硅颗粒在2-5µm。Al-50wt. %Si合金粉末的物相组成为α-Al和β-Si，无杂相生成。

(2) 不同烧结条件下合金物相仍维持α-Al相和β-Si相。烧结过程会导致网格状共晶硅消失，初生硅的尺寸增大到5-10µm。烧结温度的增加对合金显微组织的影响较小，而烧结时间的增长对显微组织的影响较大。烧结温度在525℃-600℃，时间在15min时，初生硅尺寸维持在5-10µm，而烧结时间到30-60min时，初生硅的尺寸会突破10µm，甚至连成片状。

当烧结温度在550℃，烧结时间15min时，Al-50wt.%Si合金保持Si颗粒细小均匀的同时，室温下的抗拉强度200MPa，室温下的，断裂方式为准解离断裂，断裂面的初生硅呈现明显的解理断裂，α-Al相呈现一定的韧性断裂。在高温拉伸试验中，温度达到300℃时，材料的延伸量达到了2%。烧结温度的增加使合金的致密度从99.2%增加到99.6%，但烧结时间的增长导致合金致密度降低到98.8%。平均显微硬度维持在120HV左右。

(3)不同烧结温度下Al-50wt.%Si合金的导热系数均保持在100-120 W/m·k，而烧结时间的增加会降低热导率，烧结时间60min时，合金材料的热导率仅为89W/m·k。对导热系数和热膨胀系数进行了测量并结合理论模型计算，采用H-J模型更加符合本研究制备Al-50wt.%Si合金的导热系数研究体系。烧结时间不变，烧结温度升高对合金热膨胀性有促进作用，烧结温度525℃时， CTE值为10.5×10^-6/K，而烧结温度为600℃时，CTE值为11.5×10^-6/K。温度不变，烧结时间达到 60min时，CTE值为10×10^-6/K左右。主要是由于烧结温度增加，对初生硅颗粒的圆化作用较大，颗粒的边界平滑导致对铝基体的阻碍作用减小，使得热膨胀系数增大，而烧结时间的增加对初生硅的大小改变明显，大块的初生硅连片是造成热膨胀系数减小的原因。

Hypereutectic Si-Al alloys are used in aerospace and electronic packaging materials due to their excellent properties. Because of its excellent thermal performance and machining properties, the alloy has become the focus of research in the industry. In this paper, Al-50wt. %Si alloy powder with  was selected, followed by the production of the Al-50 wt. % Si alloy used in electronic packaging by spark plasma sintering (SPS) under different parameters. Afterward, the alloy’s microstructure, phase composition, mechanical properties, coefficient of thermal expansion (CTE), and thermal conductivity (TC) were analyzed.

(1) The sphericity of powder particles is 99.6% and the fluidity is 10.40 s/50g. The particle size of the powder is about , the outer surface is smooth, regular spherical and has no obvious holes. The profile of the powder shows that the interior of the powder consists of meshed eutectic silicon and small blocks of primary silicon (2-5µm). The diffraction peaks of Al and Si are maintained in the phase analysis of Al-50wt. %Si alloy powders, and no other phase is formed.

(2) The α-Al and β-Si phases are still formed after spark plasma sintering (SPS), and no other phases were formed. The grain size of primary silicon is range of 5-10um after sintering. The increase of sintering temperature has a slight effect on the microstructure of the alloy, while the increase of sintering time has a great effect on the microstructure. When the sintering temperature is 525℃-600℃ and the time is 15min, the size of the primary silicon is 5-10µm, while when the sintering time is 30-60 min, the size of the primary silicon will break through 10µm, or even a piece.

The tensile strength of al-50wt. %Si alloy at room temperature is 200MPa. Quasi-cleavage fracture is the main mode of alloy fracture. The elongation of the material is 2% when tested at 300℃. The density of the alloy increases from 99.2% to 99.6% with the increase of sintering temperature, but decreases to 98.8% with the increase of sintering time. The average microhardness of the alloy is about 120HV.

(3) The TC and CTE were measured and calculated with the theoretical model. The H-J model was more consistent with the TC research system of Al-50wt. %Si alloy prepared in this experiment. The model took the particle size, volume fraction and interfacial thermal resistance into comprehensive consideration.The TC of Al-50wt. %Si alloy is 100-120 W/m• K at different sintering temperatures, but the TC decreases with the increase of sintering time. When sintering time is 60min, TC of alloy is only 89W/m•k. The CTE of the alloy can be promoted by the increase of sintering temperature and the same sintering time. At 525℃, the CTE value is 10.5×10^-6/K, while at 600℃, the CTE value is 11.5×10^-6/K. The CTE value is about 10×10^-6/K when the sintering time reaches 60min at the same temperature. With the increase of sintering temperature, the boundary smoothing of primary silicon particles results in the decrease of hindrance effect on aluminum matrix and the increase of CTE. The size of primary silicon changes obviously with the increase of sintering time, and the CTE decreases with the increase of bulk primary silicon.

[1] Xi Wang,Liang Zhang,Mu-lan Li. Structure and Properties of Au–Sn Lead-Free Solders in Electronic Packaging:Review[J]. Materials Transactions, 2022,63(2):93-104.

[2] 甘贵生,江兆琪. 电子封装异质材料连接研究进展[J]. 重庆理工大学学报(自然科学),2021,35(12): 94-106.

[3] Long J., Li X., Fang D., Peng P., He Q. Fabrication of diamond particles reinforced Al-matrix composites by hot-press sintering [J]. International Journal of Refractory Metals & Hard Materials, 2013, 41(4):85-89.

[4] Tan Z.Q., Li Z.Q., Fan G.L., Kai X.Z., Ji G., Zhang L.T., Zhang D. Fabrication of diamond/aluminum composites by vacuum hot pressing: Process optimization and thermal properties [J]. Composites Part B Engineering, 2013, 47(47):173-180.

[5] Tan Z.Q., Li Z.Q., Fan G.L. et al. Diamond/aluminum composites processed by vacuum hot pressing: Microstructure characteristics and thermal properties [J]. Diamond & Related Materials, 2013, 31(31):1-5.

[6] 钟鼓, 吴树森, 万里. 高Si-Cp或高Si含量电子封装材料研究进展[J]. 材料导报, 2008, 22(2): 13-17.

[7] Teng F., Kun Y.U., Luo J., Shi C.L., Dai Y.L., Xiong H.Q. Microstructures and properties of Al-50%SiC composites for electronic packaging applications[J]. Transactions of Nonferrous Metals Society of China, 2016, 26(10):2647-2652.

[8] Shenogin Sergei, Ferguson John, Ganguli Sabyasachi, Roy Ajit K.. Studying the applicability of amorphous metal alloys as interface material for power electronics packaging[J]. Materialia, 2021, 18:101142-101143.

[9] Liu X.Y., Wang W.G., Wang D., Ni D.R., Chen L.Q., Ma Z.Y. Effect of nanometer TiC coated diamond on the strength and thermal conductivity of diamond/Al composites[J]. Materials Chemistry & Physics, 2016, 182:256-262.

[10] Heremans J, Jr B.C. Thermal conductivity and thermopower of vapor-grown graphite fibers.[J]. 1985, 32(4):1981-1986.

[11] Berber S., Kwon Y.K., Tománek D. Unusually High Thermal Conductivity of Carbon Nanotubes[J]. Physical Review Letters, 2000, 84(20):4613-4616.

[12] Balandin A.A., Ghosh S., Bao W., Calizo I., Teweldebrhan D., Miao F., et al. Superior thermal conductivity of single-layer graphene.[J]. Nano Letters, 2008, 8(3):902.

[13] 周明智,许业林,雷党刚,等. 金属基复合材料在微波封装领域的研究进展[J]. 电子机械工程, 2015, 31(5):1-4.

[14] Hu Yang, Chen Chao,Wen Yingfeng, Xue Zhigang,Zhou Xingping, Shi Dean, Hu Guo-Hua, Xie Xiaolin. Novel micro-nano epoxy composites for electronic packaging application: Balance of thermal conductivity and processability[J]. Composites Science and Technology, 2021, 209:108760

[15] Liu J.W., Zhou X.X., Xin H.X. High-Si reinforced Al matrix composites prepared by powder semi-solid squeeze[J]. Journal of Alloys & Compounds, 2017, 772-778.

[16] Yu J.H., Wang C.B., Shen Q., Zhang H.M. Preparation and properties of Sip/Al composites by spark plasma sintering[J]. Materials & Design, 2012, 41:198-202.

[17] Zhu J., Wang F., Wang Y., Zhang B., Wang L. Interfacial structure and stability of a co-continuous Si C/Al composite prepared by vacuum-pressure infiltration[J]. Ceramics International, 2017, 43(8):6563-6570.

[18] Wang D.M., Zheng Z.Z., Lv J., Xu G.Q., Zhou S.A., Tang W.M, Wu Y.C. Enhanced thermal conductive 3D-SiC/Al-Si-Mg interpenetrating composites fabricated by pressureless infiltration[J]. Ceramics International, 2017, 43(2):1755-1761.

[19] Cui Y., Wang L., Ren J. Multi-functional SiC/Al Composites for Aerospace Applications[J]. Acta Aeronautica et Astronautica Sinica, 2008, 21(6):578-584.

[20] Lee H.S., Hong S.H. Pressure infiltration casting process and thermophysical properties of high volume fraction Si Cp/Al metal matrix composites[J]. Material. Science & Technology,2003, 19:1057-1066.

[21] Yoshida K., Morigami H. Thermal properties of diamond/copper composite material[J]. Microelectronics Reliability, 2004,44(2): 303-308.

[22] Bai H., Ma N.G., Lang J., Zhu C.X., Ma Y. Thermal conductivity of Cu/diamond compositesprepared by anew pretreatment of diamond powder[J]. Composites Part B (Engineering), 2013, 52: 182-186.

[23] Schubert T., Brendel A., Schmid K., Koeck T., Ciupiński L., Zieliński W., et al. Interfacial design of Cu/SiC composites prepared by powder metallurgy for heat sink applications[J]. Composites Part A Applied Science & Manufacturing, 2007, 475(1):39-44.

[24] Ullah M W, Carlberg T. Silicon crystal morphologies during solidification refining from Al-Si melts [J]. Journal of Crystal Growth, 2011, 318: 212-218.

[25] Schmitz J, Hallstedt B, Brillo J, et al. Density and thermal expansion of liquid Al-Si alloys [J]. Journal of Materials Science, 2012, 47: 3706-3712.

[26] Yurkevich N P. Short-range order and structural transformations in Al-Si melts [J]. Inorganic Materials, 2002, 38: 189-192.

[27] Sklyarchuk V, Plevachuk Y, Yakymovych A, et al. Structure sensitive properties of liquid Al-Si alloys [J]. International Journal of Thermophysics, 2009, 30: 1400-1410.

[28] Hong-Xing Lu,Qiang Zhu,Stephen P. Midson,Wen-Ying Qu,Fan Zhang,Da-Quan Li. Forming conditions of blisters during solution heat treatment of Al–Si alloy semi-solid die castings[J]. Rare Metals,2018,1:1-8.

[29] C.G. Shivaprasad, Kiran Aithal, S. Narendranath, Vijay Desai, P.G. Mukunda. Effect of combined grain refinement and modification on microstructure and mechanical properties of hypoeutectic, eutectic and hypereutectic Al-Si alloys[J]. Int. J. of Microstructure and Materials Properties,2015,10(34):274-285.

[30] Lu Shu zu. Microstructural transitions of Al-Si alloys during eutectic solidification: [dissertation], Michigan: Michigan Technological University, 1986.

[31] 安阁英. 铸件形成理论[M]. 北京: 机械工业出版社, 1986.

[32] 王渠东,丁文江,翟春泉,等.Al-Si合金中初晶Si的台阶生长. 上海交通大学学报，1999, 33(2): 142-145.

[33] 祖方遒.变质元素对铸造Al-Si合金共晶结晶的作用及机制[J].铸造, 2011, 60(11):1073-1078.

[34]薛亚军，柳秉毅．热处理工艺对铝硅合金共晶硅粒化的影响[J]．南京工程学院学报(自然科学版), 2006, 4(2):22-27.

[35] 杨伏良，甘卫平，陈招科. 高硅铝合金几种常见制备方法及细化机理[J].材料导报,2005，19(5):42-49.

[36] Sterner Rainer R. US Patent 1940922[J]. Dec, 1933, 26:1-5.

[37] 杨朝聪. 过共晶铝硅合金的细化变质[J].云南冶金,1997,40(2):7-9.

[38] 姚书芳,毛卫民,铸造铅桂合金细化变质处理的研究进展[J].铸造,49(9):512-515.

[39] Zhang Yakun, Lei Yun,Ma Wenhui,Zhai Chaoran,Shi Zhe,Ren Yongsheng. A novel approach for simultaneous recycling of Ti-bearing blast furnace slag, diamond wire saw Si powder, and Al alloy scrap for preparing TiSi2 and Al-Si alloys. [J]. Journal of hazardous materials, 2021, 427:127905.

[40] 董光明,孙国雄. 锶在铸造铝硅合金中的变质行为[J]．特种铸造及有色合金, 2005, 25(3):146-149.

[41] 孙淑红. 复合变质处理(大)过共晶铝硅合金[D].昆明:昆明理工大学.2004.

[42] Yilmaz F, Atasoy O A, Elliott R. Growth structures in aluminum-silicon alloys: the influence of Strontium [J].Journal of Crystal Growth, 1992, 118:377-384.

[43] 卢猛.复合变质对过共晶铝硅合金组织及性能的影响[D].长春:吉林大学,2001.

[44] 钟鼓.耐热低膨胀高珪铅合金及其超声半固态成形技术的研究[D].武汉:华中科技大学,2011.

[45] 王凯.电磁揽拌制备半固态大过共晶硅铝合金的研究[D].昆明:昆明理工大学,2004.

[46] 晋芳伟,任忠鸣,任维丽.强磁场下过共晶铝硅合金凝固中初晶硅的迁移行为[J].中国有色金属学报,2007,17(2): 313-319.

[47] 吴树森. 高硅铝合金的半固态压铸成形技术[J]. 金属加工(9):29-32.

[48] 刘金萍.粉末冶金法制备过共晶Al-23SI合金显微组织及性能研究[D].长沙:中南大学,2014.

[49] 解立川,彭超群,王日初.快速凝固过共晶铝硅合金粉末的形貌与显微组织[J].中国有色金属学报,2014,24(4): 130-136.

[50] 彭建,王日初,彭超群.喷射沉积Al-27%Si合金的半固态挤压成形[J].中国有色金属学报,2014,24(4): 905-911.

[51] 虞觉奇,黄红武.双辊快速凝固Al-Si合金的显微组织[J].材料研究学报,1998,12(6): 594-597.

[52] 彭超群.喷射成形技术[M].长沙:中南大学出版社,2004,10.

[53] 陈振华.多层喷射沉积技术及应用[M].长沙:湖南大学出版社,2003:1-4.

[54] 谢锐. 纳米结构ODS钢的新型制备工艺及微观组织与力学性能的研究[D].东北大学,2015.

[55] 曲选辉.粉末 冶金原理及工艺[M],北京:冶金工业出版社,2013,217-220.

[56] 王松,谢明,张吉明等.放电等离子烧结技术进展[J],贵金属,2012,33(3):73-77.

[57] 张久兴,刘科高,周美玲.放电等离子烧结技术的发展和应用[J],粉末冶金技术,2002,20(3):129-134.

[58] 台锋,刘春明.一种超细晶粒纳米结构氧化物弥散强化钢的制备方法[P],专利号ZL2010105941639,2010.

[59] S.Pasebani,I.Charit,Effect of alloying elements on the microstructure and mechanical properties of nanostructured ferritic steels produced by sparks plasma sintering[J], Journal of Alloys and Compounds, 2014,599:206-211.

[60] K. N. Allahar, J.Burns, B. Jaques et al. Ferritic oxide dispersion strengthened alloys by spark plasma sintering [J], Journal of Nuclear Materials, 2013,443(1-3):256-265.

[61] Y. P. Xia, X.P. Wang, Z. Zhuang et al. Microstructure and oxidation properties of 16Cr-5Al-ODS steel prepared by sol-gel and spark plasma sintering methods[J], Journal of Nuclear Materials, 2013,432(1-3):198-204.

[62] Q. X. Sun, Y, Zhou, Q.F. Fang et al. Development of 9Cr-ODS ferritic-martensitic steel prepared by chemical reduction and mechanical milling [J],Journal of Alloys and Comppunds, 2014,598:243-247.

[63] 毕莹.亚微米级银靶粉的制备研究[D].东北大学.2010.

[64] 余静.原位反应制备Al3Ti颗粒增强铝基复合材料及其性能研究[D].西安科技大学.2015.

[65] 张帅. SPS制备Si_3N_4/TiC基陶瓷刀具及其自修复和自润滑性能研究[D].齐鲁工业大学,2021.

[66] 黄思德. 碳化硅颗粒增强铝基复合材料的制备与性能研究[D]. 合肥工业大学.2012.

[67] 刘金萍. 粉末冶金法制备过共Al-23Si合金显微组织及性能的研究[D].中南大学,2014.

[68] 庄成康,丁华平,马云飞,刘辉,龚攀,王新云.放电等离子烧结制备非晶合金的研究进展[J].稀有金属材料与工程,2021,50(03): 1096-1106.

[69] Nouari Saheb, Zafar Iqbal, Abdullah Khalil, Abbas Saeed Hakeem, Nasser Al Aqeeli, Tahar Laoui, Amro Al-Qutub, René Kirchner. Spark Plasma Sintering of Metals and Metal Matrix Nanocomposites: A Review [J]. Journal of Nanomaterials. 2012, 13

[70] Akihisa Inoue. Stabilization of metallic supercooled liquid and bulk amorphous alloys[J]. Acta Materialia. 2000,48(1):279-306,

[71] Guangming He, Qingjun Chen. Interpretation of densification behavior of spark plasma sintered Fe-based metallic glass powders from the standpoint of internal friction [J]. Journal of Alloys and Compounds. 2019,797:213-221.

[72] Q. Chen, C.Y. Tang, K.C. Chan, L. Liu. Viscous flow during spark plasma sintering of Ti-based metallic glassy powders[J].Journal of Alloys and Compounds.2013,557:98-101.

[73] 贾建波, 杨越, 孙威, 仲晓晓, 徐岩, 顾勇飞, 骆俊廷.放电等离子烧结制备Ti-22Al-25Nb合金及致密化机理[J].中国有色金属学报, 2019,29(07):1399-1407.

[74] 李韶雨,易健宏,李凤仙.烧结参数对超细晶铁粉的SPS烧结的影响[J].热加工工艺,2016,45(18):69-72.

[75] A.V. Bune, S. Sen, S. Mukherjee, et al. Effect of melt convenction at various gravity levels and orientations on the forces acting on a large spherical particle in the vicinity of a solidification interface[J]. Journal of Crystal Growth. 2000, 211: 446-451.

[76]田梅娟,坚增运,海瑞.Al-Si合金凝固收缩率的研究进展[J].铸造, 2020, 69(10):1060-1064.

[77] 陈保安,潘学东,赵丽丽,张强,丁一,祝志祥,陈新,彭朝,张磊,陈素红.Al-Mg-Si系铝合金导体材料的研制[J].特种铸造及有色合金,2020,40(09):1038-1041.

[78] 杨文涛,何鹏飞,刘明,周永欣,王海斗,马国政,白宇.快速凝固过共晶铝硅合金的显微组织及摩擦学行为研究现状[J].材料导报,2021,35(11):11127-11137.

[79] 何云飞. 过共晶铝硅熔体在电磁定向凝固过程中初晶硅的分离研究[D].昆明理工大学,2019.

[80] 余志华, 张建云, 周贤良, 邹爱华. 电子封装SiC_p/Al复合材料导热性能研究与进展[J].金属功能材料,2009,16(01): 59-64.

[81] 王晓阳, 朱丽娟, 刘越. 粉末冶金法制备A1SiC电子封装材料及性能[J].电子与封装,2007,7(5):9-11

[82] 黄培云编.粉末冶金原理[M].冶金工业出版社,1997

[83] Jae Chul Lee, Ji Young Byun，Sung BaePark.Prediction of Si contensts to suppress the formation ofA14C3 in the SiCP/A1 composites [J].Acta Mate 1998, 46(5): 1771-1780

[84] Jae Chul Lee, Sung Bae Park, Hyun Kwang Seok,et al. Predietion of Si contenst to suppress the interfacial reaction in the SiCP/2014A1 composites [J].Acta Mater, 1998,46(8):2635-2643

[85] Lee JAE CHUL. Modification of the interface in SiC/A1 composites [J].Metal MaterTrans, 2000, 31A:2361

[86] 梁建芳. 无压浸渗制备Al/SiCp电子封装材料的结构与性能[D]. 西北工业大学,2006.