稀土镁合金的超声固相连接：微观组织演变特征与强化机制研究

Solid-state joining of rare-earth magnesium alloys via ultrasonic welding: microstructural evolution characteristics and strengthening mechanism

摘要

焊接热循环过程中，镁合金易发生晶粒粗化和析出相结构改变，导致合金微观组织损伤，进而削弱焊接接头性能。如何降低焊接过程中镁合金的强度损伤，已成为镁合金加工领域的研究热点。本工作采用超声振动辅助连接工艺对含 Ce 稀土镁合金进行连接，并系统研究接头的微观组织演变与强化机制。研究结果表明，超声振动诱发的声致塑性与热效应促使接触界面发生剧烈的动态再结晶，显著细化超声作用区的晶粒，晶粒尺寸从母材的 250 μm 细化至 10～30 μm。与此同时，超声振动产生的高频机械剪切将接头内粗大的析出相破碎为尺寸均匀、弥散分布的微米/亚微米颗粒，可显著增强沉淀强化效应。此外，稀土元素 Ce 在晶界偏聚形成热稳定相，有效钉扎晶界并抑制位错滑移，从而减缓焊接接头的微观组织改变。力学性能测试结果表明，在细晶强化、弥散强化与稀土元素强化的协同作用下，接头拉剪强度达 194.9 MPa，接头强度为母材强度的 92.4%，且断裂模式由界面脆性断裂向基体韧性断裂转变。

Abstract

During welding thermal cycles, magnesium alloys are highly susceptible to grain coarsening and structural changes of precipitates, leading to microstructural damage and subsequently deteriorating the performance of welded joints. Consequently, mitigating the strength degradation of magnesium alloys during welding has attracted considerable research attention in the field of magnesium alloy processing. In this study, an ultrasonic vibration-assisted solid-state joining process is employed to join a Ce-containing rare-earth magnesium alloy, and the microstructural evolution and strengthening mechanisms of the joints are systematically investigated. The results indicate that the acoustic plasticity and thermal effects induced by ultrasonic vibration promote intense dynamic recrystallization at the contact interface, resulting in significant grain refinement within the ultrasonic-affected zone, with grain sizes reduced from 250 μm in the base metal to 10-30 μm in the joint region. Simultaneously, the high-frequency mechanical shearing generated by ultrasonic vibration fragments coarse precipitates into uniformly distributed micro- and submicro-sized particles, thereby significantly enhancing precipitation strengthening. In addition, the segregation of rare-earth element Ce at the grain boundaries leads to the formation of thermally stable phases, which effectively pin grain boundaries and suppress dislocation motion, thereby mitigating microstructural degradation during the joining process. Mechanical testing demonstrates that the synergistic effects of grain-refinement strengthening, dispersion strengthening, and rare-earth strengthening enable the joint to achieve a lap-shear strength of 194.9 MPa, equivalent to 92.4% of the base metal strength. Additionally, the fracture mode transitions from interfacial brittle fracture to matrix ductile fracture. The findings provide theoretical basis and technical guidance for the development of low-damage, highly reliable joining technologies for rare-earth magnesium alloys.

关键词

稀土镁合金 / 超声振动 / 第二相破碎 / 析出强化 / 晶粒细化

Key words

rare-earth magnesium alloy / ultrasonic vibration / second-phase fragmentation / precipitation strengthening / grain refinement

参考文献

[1] Schubert E, Klassen M, Zerner I, et al. Light—weight structures produced by laser beam joining for future applications in automobile and aerospace industry[J].Journal of Materials Processing Technology, 2001, 115(1):2-8.

[2] Pfestorf M. Manufacturing of high strength steel and aluminum for a mixed material body in white[M]//Sheet Metal 2005. Stafa: Trans Tech Publications Ltd., 2005: 109-126.

[3] Song J F, She J, Chen D L, et al. Latest research advances on magnesium and magnesium alloys worldwide[J].Journal of Magnesium and Alloys, 2020, 8(1):1-41.

[4] 曾小勤，陈义文，王静雅，等. 高性能稀土镁合金研究新进展[J].中国有色金属学报，2021，31（11）：2963-2975.

[5] Zeng X Q, Chen Y W, Wang J Y, et al. Research progress of high—performance rare earth magnesium alloys[J].The Chinese Journal of Nonferrous Metals, 2021, 31(11):2963-2975.

[6] Lyu J B, Kim J, Liao H X, et al. Effect of substitution of Zn with Ni on microstructure evolution and mechanical properties of LPSO dominant Mg—Y—Zn alloys[J].Materials Science and Engineering: A, 2020, 773:138735.

[7] Wu G H, Wang C L, Sun M, et al. Recent developments and applications on high—performance cast magnesium rare—earth alloys[J].Journal of Magnesium and Alloys, 2021, 9(1):1-20.

[8] 陈燕飞，朱政强，汪光鑫. 基于第一性原理研究稀土 Ce 对镁合金的强化机制[J].稀有金属材料与工程，2022，51（10）：3762-3776.

[9] Chen Y F, Zhu Z Q, Wang G X. Strengthening mechanism of rare earth Ce on magnesium alloy based on first—principle calculations[J].Rare Metal Materials and Engineering, 2022, 51(10):3762-3776.

[10] Luo Q, Guo Y L, Liu B, et al. Thermodynamics and kinetics of phase transformation in rare earth—magnesium alloys: a critical review[J].Journal of Materials Science & Technology, 2020, 44:171-190.

[11] 王帅，刘泽宇，叶建林，等. 镁合金激光焊接气孔形成机制及调控措施研究进展[J].稀有金属材料与工程，2025，54（6）：1630-1640.

[12] Wang S, Liu Z Y, Ye J L, et al. Advance in formation mechanisms of porosity defects and regulatory measures in laser beam welding of magnesium alloys[J].Rare Metal Materials and Engineering, 2025, 54(6):1630-1640.

[13] Wang L Y, Huang J, Li Z G, et al. Microstructure and strengthening mechanism of fiber laser—welded high—strength Mg—Gd—Y—Zr alloy[J].Journal of Materials Engineering and Performance, 2016, 25(10):4506-4513.

[14] Santhanakrishnan S, Kumar N, Dendge N, et al. Macro— and microstructural studies of laser—processed WE43 (Mg—Y—Nd) magnesium alloy[J].Metallurgical and Materials Transactions B, 2013, 44(5):1190-1200.

[15] Jiryaei Sharahi H, Pouranvari M, Movahedi M. Pre—weld friction stir processing enabling strong and ductile fusion welds on AZ91 magnesium alloy[J].Science and Technology of Welding and Joining, 2023, 28(2):162-171.

[16] Yang Q Y, Zhang L, Chen Y F, et al. Influence of post—weld tempering pulse on microstructure and mechanical properties of NDM2 rare earth magnesium alloy joint welded by resistance spot welding[J].Journal of Materials Engineering and Performance, 2023, 32:3094-3105.

[17] 吴国华，张国庆，童鑫，等. 镁稀土合金焊接工艺及组织性能研究现状与展望[J].有色金属科学与工程，2021，12（1）：116-125.

[18] Wu G H, Zhang G Q, Tong X, et al. Research status and prospect of welding process and mechanical properties of Mg—RE alloy[J].Nonferrous Metals Science and Engineering, 2021, 12(1):116-125.

[19] Ji H, Liu WC, Wu G H, et al. Influence of Er addition on microstructure and mechanical properties of as—cast Mg—10Li—5Zn alloy[J].Materials Science and Engineering: A, 2019, 739:395-403.

[20] Scintilla L D, Tricarico L, Brandizzi M, et al. Nd:YAG laser weldability and mechanical properties of AZ31 magnesium alloy butt joints[J].Journal of Materials Processing Technology, 2010, 210(15):2206-2214.

[21] 王克亮. 激光电弧复合焊接数值模拟[D]. 长春：长春理工大学，2009.

[22] Wang K L. Numerical simulation of laser—arc hybrid welding[D]. Changchun: Changchun University of Science and Technology,2009.

[23] Shen J, Wen L B, Li Y, et al. Effects of welding speed on the microstructures and mechanical properties of laser welded AZ61 magnesium alloy joints[J].Materials Science and Engineering: A, 2013, 578:303-309.

[24] 焦锐，陈积翠，唐亚红. 动力集中动车组全铝合金司机室制造工艺[J].金属加工（热加工），2022（12）：53-56.

[25] Jiao R, Chen J C, Tang Y H. Manufacturing process of all aluminum alloy cab for power centralized EMU[J].MW Metal Forming, 2022(12):53-56.

[26] 刘志平，王金金，王立夫，等. CRH3 铝合金高速动车组焊接技术[J].金属加工（热加工），2010（16）：10-12.

[27] Liu Z P, Wang J J, Wang L F, et al. Welding technology of CRH3 aluminum alloy high—speed EMU[J].MW Metal Forming, 2010(16):10-12.

[28] 刘陈飘，刘凯，王芳丽，等. 基于相场法的铝锂合金搅拌摩擦焊接头脆性断裂数值模拟[J].焊接学报，2025，46（10）：33-43.

[29] Liu C P, Liu K, Wang F L, et al. Numerical simulation of brittle fracture of Al—Li alloy joint by friction stir welding based on phase field method[J].Transactions of the China Welding Institution, 2025, 46(10):33-43.

[30] Chen Y F, Zhu Z Q, Siddiq M A, et al. Minimal strength loss and corresponding mechanisms in the ultrasonic joining of magnesium alloys[J].Materials Science and Engineering: A, 2025, 934:148346.

[31] Liu W M, Yan Y F, Ni R Y, et al. Influence of preheating temperature on the friction stir welded ME20M magnesium alloy[J].Science and Technology of Welding and Joining, 2021, 26(2):136-143.

[32] Liu Q P, Li W, Zhu L, et al. Temperature—dependent friction coefficient and its effect on modeling friction stir welding for aluminum alloys[J].Journal of Manufacturing Processes, 2022, 84:1054-1063.

[33] 王鹏，吴璇，张喆，等. 搅拌摩擦焊在镁合金焊接中的应用与进展[J].兵器材料科学与工程，2025，48（1）：155-164.

[34] Wang P, Wu X, Zhang Z, et al. Application and progress of friction stir welding in magnesium alloy welding[J].Ordnance Material Science and Engineering, 2025, 48(1):155-164.

[35] 马琳，温琦，李鸣申，等. AZ31B 镁合金超声强化 TLP 接头组织演变及缺陷分析[J].焊接学报，2020，41（6）：30-36.

[36] Ma L, Wen Q, Li M S, et al. Microstructure evolution and defect analysis of ultrasonic—assisted transient liquid phase bonding of AZ31B Mg alloy[J].Transactions of the China Welding Institution, 2020, 41(6):30-36.

[37] Abbas Z, Zhao L, Deng J X, et al. Advances in ultrasonic welding of lightweight alloys: a review[J].High Temperature Materials and Processes, 2023, 42:20220298.

[38] 邱田伟，王重阳，安钰坤，等. 梯度能量对多层镁合金超声焊接接头组织及力学性能的影响[J].兵器材料科学与工程，2024，47（3）：28-35.

[39] Qiu T W, Wang C Y, An Y K, et al. Effect of gradient energy on microstructure and mechanical properties of ultrasonic welded multi—layer Mg alloy joints[J].Ordnance Material Science and Engineering, 2024, 47(3):28-35.

[40] Zhao D W, Jiang C, Zhao K M. Ultrasonic welding of AZ31B magnesium alloy and pure copper: microstructure, mechanical properties and finite element analysis[J].Journal of Materials Research and Technology, 2023, 23:1273-1284.

[41] Cui M F, Zheng Z T, Du P, et al. A double molten pool laser welding process for joining magnesium alloys and aluminum alloys: the process, microstructure and mechanical properties of joints[J].Materials Today Communications, 2023, 35:106116.

[42] Peng H, Chen D L, Guo S F, et al. Dissimilar ultrasonic spot welding of rare—earth containing ZEK100 magnesium—to—aluminum alloy with a zinc interlayer: microstructural evolution and mechanical properties[J].Journal of Manufacturing Processes, 2023, 92:422-434.

[43] Baradarani F, Emami S, Mostafapour A, et al. Influence of ultrasonic vibration on the microstructure and texture evolution of AZ91 magnesium alloy during ultrasonic—assisted friction stir welding[J].Welding in the World, 2021, 65(12):2371-2382.

[44] Sabat R K, Brahme A P, Mishra R K, et al. Ductility enhancement in Mg—0.2%Ce alloys[J].Acta Materialia, 2018, 161:246-257.

[45] MacKenzie L W F, Pekguleryuz M O. The recrystallization and texture of magnesium—zinc—cerium alloys[J].Scripta Materialia, 2008, 59(6):665-668.

[46] Ramirez A, Qian M, Davis B, et al. Potency of high—intensity ultrasonic treatment for grain refinement of magnesium alloys[J].Scripta Materialia, 2008, 59(1):19-22.

[47] Hort N, Huang Y, Kainer K U. Intermetallics in magnesium alloys[J].Advanced Engineering Materials, 2006, 8(4):235-240.

[48] Panteli A, Robson J D, Brough I, et al. The effect of high strain rate deformation on intermetallic reaction during ultrasonic welding aluminium to magnesium[J].Materials Science and Engineering: A, 2012, 556:31-42.

[49] Robson J, Panteli A, Prangnell P B. Modelling intermetallic phase formation in dissimilar metal ultrasonic welding of aluminium and magnesium alloys[J].Science and Technology of Welding and Joining, 2012, 17(6):447-453.

[50] Song D B, Wang T, Zhao Y B, et al. Microstructural characteristics and mechanical properties of ultrasonic—assisted electron beam welding joints of rare—earth magnesium alloy[J].Journal of Materials Engineering and Performance, 2025, 34(7):6138-6147.

[51] Zhao J J, Wu C S, Su H. Ultrasonic effect on thickness variations of intermetallic compound layers in friction stir welding of aluminium/magnesium alloys[J].Journal of Manufacturing Processes, 2021, 62:388-402.

[52] Naik S N, Walley S M. The Hall—Petch and inverse Hall—Petch relations and the hardness of nanocrystalline metals[J].Journal of Materials Science, 2020, 55(7):2661-2681.

基金资助

中国博士后科学基金(2025M770017)

江西省自然科学基金(20252BAC200638)

湖南省教育厅科学研究项目优秀青年项目(24B0986)