王春晖, 李昕童, 钱凌云, 付华栋, 程兰月, 孙朝阳. Mg/Al双金属固相复合界面特征与性能[J]. 工程科学学报. DOI: 10.13374/j.issn2095-9389.2024.04.09.004
引用本文: 王春晖, 李昕童, 钱凌云, 付华栋, 程兰月, 孙朝阳. Mg/Al双金属固相复合界面特征与性能[J]. 工程科学学报. DOI: 10.13374/j.issn2095-9389.2024.04.09.004
WANG Chunhui, LI Xintong, QIAN Lingyun, FU Huadong, CHENG Lanyue, SUN Chaoyang. Study on the microstructural characteristics of Mg/Al bimetallic solid-phase composite interfaces[J]. Chinese Journal of Engineering. DOI: 10.13374/j.issn2095-9389.2024.04.09.004
Citation: WANG Chunhui, LI Xintong, QIAN Lingyun, FU Huadong, CHENG Lanyue, SUN Chaoyang. Study on the microstructural characteristics of Mg/Al bimetallic solid-phase composite interfaces[J]. Chinese Journal of Engineering. DOI: 10.13374/j.issn2095-9389.2024.04.09.004

Mg/Al双金属固相复合界面特征与性能

Study on the microstructural characteristics of Mg/Al bimetallic solid-phase composite interfaces

  • 摘要: Mg/Al双金属层状复合材料因兼具镁合金低密度和铝合金耐腐蚀的特性,在轻量化与高性能成形制造方面应用需求巨大. 而金属材料接触面在固态下直接结合的双金属固相复合工艺,因避免了液–液复合或液–固复合中氧化、夹杂等缺陷对复合材料性能的影响,在双金属复合技术中具有显著的优势. 为阐明Mg/Al双金属固相复合过程中热变形条件对复合界面特征和性能的影响规律,开展了变形温度300~430 ℃、应变率5×10−3~1 s−1和变形量20%~40%条件下的热压缩复合实验,采用扫描电镜、能谱仪和维氏硬度仪获得了复合界面的微观形貌、元素和硬度的分布规律. 结果表明:随着应变率降低、变形量增加和变形温度升高,元素扩散时间增长、扩散能力增强,过渡区总厚度增加,形成了Mg17Al12相和Al3Mg2相组成的高硬度金属间化合物层. 在此基础上,通过建立金属间化合物层的厚度演化模型,结合双金属冶金结合的临界变形量计算公式,构建了Mg/Al双金属复合界面特征随热变形条件演化图. 计算结果说明:较高温度(>400 ℃)和较高应变率(~1 s−1)的变形条件在保证Mg/Al双金属冶金结合同时,可以抑制金属间化合物层的出现和长大,从而有助于良好复合界面的实现.

     

    Abstract: Mg/Al bimetallic layered composites are in great demand for lightweight and high-performance manufacturing applications owing to the advantageous combination of the low density of magnesium alloys and the corrosion resistance of aluminum alloys. The bimetallic solid-phase composite fabrication process, in which the contact surfaces of metal materials are directly combined in the solid state, offers significant advantages in bimetallic composite technology. This process avoids the detrimental effects of oxidation, inclusions, and other defects that can impact the performance of composite materials formed through liquid–liquid or liquid–solid composite processes. Temperature, strain rate, and strain are critical parameters in many joining and forming processes of Al/Mg alloy hybrid structures/components, but the relationship between these parameters and interfacial bonding strength remains to be quantified. In this study, hot compression composite experiments were conducted to elucidate the influence of heat deformation conditions on the performance of the Mg/Al bimetallic composite interface. The experiments were performed at deformation temperatures of 300–430 ℃, strain rates of 5×10−3–1 s−1, and strains of 20%–40%. A scanning electron microscope with energy dispersive spectroscopy (SEM–EDS) and a Vickers hardness tester were used to analyze the microstructure, element distribution, and hardness distribution of the composite interface. The results showed that the bonding interface was not effectively formed owing to the presence of micro-gaps at a strain of 0.2 or a temperature of 300 ℃. Furthermore, the strain rate mainly affected the shape of the bonding interface, indicating that strain and temperature were the critical factors influencing metallurgical bonding in the bimetallic compounding process. As the strain rate decreased and deformation and temperature increased, the element diffusion time increased, and diffusion ability improved. This resulted in a thicker transition region and the formation of high-hardness intermetallic compounds (IMCs) composed of Mg17Al12 and Al3Mg2 phases. According to this, an evolution model of the intermetallic compound layer thickness in the transition region, parameterized by the elemental diffusion activation energy, was established. Through the incorporation of the critical strain required for the bimetal to achieve metallurgical bonding, a diagram illustrating the evolution of the Mg/Al bimetallic composite interface under various heat deformation conditions was constructed. Metallurgical bonding was achieved through the complete diffusion of metal atoms at the interface; however, the hardness and brittleness of the resulting intermetallic compound layer were not conducive to the quality of the Mg/Al bimetallic interface. Therefore, considering metallurgical bonding and the characteristics of the intermetallic compound layer is essential. Controlling the extent of elemental diffusion allowed for minimizing the thickness of the intermetallic compound layer while ensuring effective interfacial metallurgical bonding. The calculation results indicated that deformation conditions of higher temperature (>400 ℃) and higher strain rate (~1 s−1) could inhibit the formation and growth of the intermetallic compound layer while ensuring metallurgical bonding, thus contributing to a high-quality composite interface. The combination of high strain rates and high temperatures enabled the formation of a fully bonded interface with a minimal intermetallic compound layer thickness, maximizing bonding strength. The research findings and developed models can guide the optimization of parameters associated with the Mg/Al bimetallic joining or forming process via plastic deformation.

     

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