初始时效状态对超低温轧制2024铝合金微观组织及力学性能的影响

doi:10.3901/JME.2025.14.081

摘要/Abstract

摘要： 冷喷涂增材制造技术由于具有非常低的热量输入，能够有效避免晶粒粗大，高内应力以及热裂等缺陷而受到越来越多的关注。但是冷喷涂2024铝合金沉积体内由于孔洞以及高密度位错的存在导致其性能较低。对于铝合金来讲，“超低温轧制+时效处理”是一种有效的组织调控及性能优化方法，但是目前不同初始时效状态对2024铝合金在超低温轧制过程中微观结构和性能的影响机制尚不清楚。因此，基于X射线衍射(X-ray diffraction, XRD)以及透射电子显微镜(Transmission electron microscopy, TEM)等测试手段对比了固溶态和预时效态两种不同初始状态的2024铝合金在超低温轧制和随后的低温时效过程中位错和析出相结构的演变规律，阐明了初始的T相以及GPB区对轧制过程中位错演变的影响机制。结果表明，预时效试样的GPB区在能够显著提升超低温轧制后合金的位错密度和均匀性。进一步的，高密度的位错在随后的低温时效处理中作为析出相的形核位点，促进了大量弥散的，尺寸细小(15～20 nm)的沉淀的析出。高密度的析出物能有效地纠缠并储存位错，使其表现出更优的强塑性，屈服强度达到488 MPa，均匀伸长率为8.5%。强度比商用的传统峰值时效2024合金高出大约40%，同时保持了相近的均匀变形能力。结果也证明了超低温轧制对冷喷涂铝合金的性能优化具有显著的效果。

关键词: 冷喷涂2024铝合金, 超低温轧制, 初始时效状态, 位错, 沉淀相, 力学性能

Abstract: Cold spray additive manufacturing technology has garnered increasing attention due to its extremely low heat input, which effectively avoids defects such as coarse grains, high residual stress, and thermal cracks. However, the performance of CSAM-processed 2024 aluminum alloy deposits remains suboptimal owing to the presence of pores and high-density dislocations. For aluminum alloys, the "cryogenic rolling + aging treatment" strategy serves as an effective approach for microstructure regulation and performance optimization. Nevertheless, the influence mechanisms of different initial aging states on the microstructure and properties of 2024 aluminum alloy during cryogenic rolling remain unclear. Therefore, systematically compared the evolution of dislocations and precipitates in solution-treated and pre-aged 2024 aluminum alloys during cryogenic rolling and subsequent low-temperature aging using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The research elucidated the regulatory effects of initial T-phase and GPB zones on dislocation evolution during rolling. Results demonstrate that the GPB zones in pre-aged specimens significantly enhance the density and homogeneity of dislocations after cryogenic rolling. Furthermore, these high-density dislocations act as nucleation sites during subsequent low-temperature aging, promoting the precipitation of numerous finely dispersed S′ precipitates (15-20 nm). The high-density S′ precipitates effectively entangle and store dislocations, resulting in superior strength-ductility synergy: a yield strength of 488 MPa with 8.5% uniform elongation. The strength surpasses that of commercial peak-aged 2024 alloy by approximately 40% while maintaining comparable uniform deformation capability. This work validates the remarkable effectiveness of cryogenic rolling in optimizing the properties of cold-sprayed aluminum alloys.

Key words: cold sprayed 2024 aluminum alloy, cryogenic rolling, initial aging stages, dislocation, precipitation, mechanical properties

中图分类号:

TG146

张凌宇, 戚宇彤, 陈伟, 李淑慧, 林忠钦. 初始时效状态对超低温轧制2024铝合金微观组织及力学性能的影响[J]. 机械工程学报, 2025, 61(14): 81-90.

ZHANG Lingyu, QI Yutong, CHEN Wei, LI Shuhui, LIN Zhongqin. Effect of Initial Aging Treatment on the Microstructure and Mechanical Properties of Cryorolled 2024 Aluminum Alloy[J]. Journal of Mechanical Engineering, 2025, 61(14): 81-90.

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