姚梦龄,赵庆,杨欢,等.变形前初始组织对ECAP变形Mg-9Al-1Si合金高温蠕变性能的影响[J].精密成形工程,2025,17(4):129-137.
YAO Mengling,ZHAO Qing,YANG Huan,et al.Effect of Initial Microstructure before Deformation on High-temperature Creep Properties of ECAP Deformed Mg-9Al-1Si Alloy[J].Journal of Netshape Forming Engineering,2025,17(4):129-137. |
| 变形前初始组织对ECAP变形Mg-9Al-1Si合金高温蠕变性能的影响 |
| Effect of Initial Microstructure before Deformation on High-temperature Creep Properties of ECAP Deformed Mg-9Al-1Si Alloy |
| 投稿时间：2024-05-15 |
| DOI：10.3969/j.issn.1674-6457.2025.04.013 |
| 中文关键词: Mg-9Al-1Si 等通道转角挤压(ECAP) 预处理 显微组织 蠕变性能 |
| 英文关键词: Mg-9Al-1Si equal channel angular pressing (ECAP) pretreatment microstructure creep properties |
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| 中文摘要: |
| 目的 研究不同预处理工艺对Mg-Al-Si合金变形组织演变和高温蠕变性能的影响规律，探索不同预处理工艺后变形合金的高温蠕变机制。方法 在Mg-9Al-1Si耐热镁合金ECAP变形前，通过超声(UC)结合固溶(T4)和时效(T6)处理调控获得不同形貌的初始微观组织，经过ECAP变形后，采用OM、SEM和XRD等分析测试手段对挤压前后的合金进行显微组织观察和物相分析，研究初始组织对ECAP态合金组织演变的影响规律;利用电子蠕变试验机对挤压后试样进行高温蠕变性能测试，通过计算分析不同预处理状态下挤压合金的稳态蠕变速率和蠕变激活能，探索出合金的高温蠕变机制。结果 超声预处理能够细化合金基体枝晶，改善Mg2Si与Mg17Al12相的形貌和分布，同时促进层片状Mg17Al12相析出。经ECAP变形后，不同初始组织的基体晶粒均显著细化，其中未预处理直接挤压态合金的粗晶区与细晶区混杂交错，粗大的Mg2Si和Mg17Al12相未得到完全碎化;经UC单级预处理的挤压态合金内部无明显的混晶组织，晶粒大小分布均匀，平均尺寸达到25.99 μm，同时第二相得到显著碎化且均匀分布;经(UC+T4/T6)双级预处理后，挤压态合金的晶粒尺寸进一步细化，但出现了粗晶区与细晶区的混晶组织。在448 K/50 MPa的蠕变条件下，经UC单级预处理后的ECAP态合金蠕变性能最好，稳态蠕变速率为4.17×10−7 s−1，与未预处理直接ECAP态合金相比，降低了1个数量级，其蠕变激活能为134.475 kJ/mol。结论 在448~498 K/50 MPa的蠕变条件下，经UC单级预处理和UC+T4双级预处理后，挤压态Mg-9Al-1Si合金的蠕变机制均为受自由扩散控制的位错攀移机制，UC+T6双级预处理挤压态合金的蠕变机制为受晶界扩散控制的位错滑移机制。 |
| 英文摘要: |
| The work aims to study the influence of different pretreatment processes on the evolution of deformation microstructure and creep behavior of the Mg-Al-Si alloy, and explore the high-temperature creep mechanism of deformed alloys after different pretreatment processes. In the experiment, the initial microstructures of different morphologies in the Mg-9Al-1Si heat-resistant magnesium alloy were controlled through ultrasonic combined solution and aging treatments before ECAP deformation. The microstructure observation and phase analysis of the alloy before and after extrusion were carried out by OM, SEM, and XRD. An electronic creep testing machine was used to test the high-temperature creep performance of extruded specimens, the steady-state creep rates and creep activation energy of extruded alloys under different pretreatment states were calculated and analyzed to explore the high-temperature creep mechanism of the alloys. Ultrasonic pretreatment could refine the dendrites in the alloy matrix, improve the morphology and distribution of Mg2Si and Mg17Al12 phases, and promote the precipitation of layered Mg17Al12 phases. After ECAP deformation, the matrix grains of different initial microstructures were significantly refined, among which the coarse and fine grain regions of the untreated extruded alloy were mixed and interlaced. Moreover, the coarse Mg2Si and Mg17Al12 phases in the extruded alloy were not completely fragmented. The extruded alloy with UC single-stage pretreatment had no obvious mixed crystal structure inside, and the grain size distribution was uniform, with an average size of 25.99 μm. At the same time, the second phase exhibited significant fragmentation and uniform distribution. The grain size of the extruded alloy with UC+T4/T6 two-stage pretreatment was further refined, but a mixed grain structure appeared in the coarse and fine grain regions. Under creep conditions of 448 K and 50 MPa, the ECAP state alloy treated with UC single-stage pretreatment exhibited the best creep performance. Its steady-state creep rate was 4.17×10−7 s−1, which was one order of magnitude lower than that of the untreated ECAP state alloy. The calculated creep activation energy of the ECAP state alloy treated with UC single-stage pretreatment was 134.475 kJ/mol. Under the creep conditions of 448-498 K and 50 MPa, the creep mechanism of the extruded Mg-9Al-1Si alloy after single stage UC pretreatment and UC+T4 double stage pretreatment is controlled by free diffusion, while the creep mechanism of the extruded Mg-9Al-1Si alloy after UC+T6 double stage pretreatment is controlled by grain boundary diffusion. |
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