(1. 中南大学 材料科学与工程学院，长沙 410083；
2. 中国铝业股份有限公司 郑州研究所，郑州 450041)
摘 要: 研究不同温度下2024铝合金的蠕变行为，采用金相显微镜、扫描电镜以及透射电子显微镜观察蠕变后合金的微观组织变化。结果表明：在125~200 ℃蠕变温度下，当蠕变寿命接近100 h时，2024铝合金的蠕变应力随着温度的升高明显下降；与125 ℃相比，150 ℃时合金的蠕变应力下降9.3%，在175 ℃时合金的蠕变应力下降30.3%；当蠕变温度为200 ℃时，该合金的蠕变应力下降幅度达到45.8%；在125~175 ℃下，合金在蠕变过程中的变形机制主要为位错在晶内的滑移；在200℃时，合金晶界开始发生滑移，合金变形由晶界滑移与位错在晶内的滑移协调完成；在合金蠕变断面上存在大量微孔，随着蠕变温度的升高，微孔的尺寸明显变大，当微孔尺寸超过3 μm时，微孔对合金的断裂机制有显著影响；在125和150 ℃下，合金的蠕变断口呈现韧窝型穿晶断裂特征；在175和200 ℃下，合金的蠕变断口呈现沿晶断裂特征。
关键字: 2024铝合金；蠕变温度；蠕变行为；蠕变应力；变形机制
（1. School of Material Science and Engineering, Central South University, Changsha 410083, China;
2. Zhengzhou Research Institute of CHALCU, Aluminum Corporation of China Limited, Zhengzhou 450041, China）
Abstract:The creep behaviors of 2024 aluminum alloy were investigated at different temperatures. The microstructures of alloys after creep were observed by optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the creep stress of this alloy decreases with increasing the creep temperature in the range of 125−200 ℃ when the creep lifetime is close to 100 h. Compared with the alloy crept at 125 ℃, the creep stress of alloy crept at 150 ℃ is decreased by 9.3%; the creep stress at 175 ℃ is decreased by 30.3%. When the creep temperature increases to 200 ℃, the creep stress is decreased by 45.8%. The main deformation mechanism of the alloy is intragranular slipping of the dislocations in the creep temperature range of 125−175 ℃. Grain boundary slidings happen in this alloy at the creep temperature of 200 ℃ and the deformation of this alloy is coordinated by intragranular slip and grain boundary sliding. Lots of micropores exist on the fracture surfaces of the crept alloys. The sizes of these micropores increase with increasing the creep temperature. When the sizes of micropors are larger than 3 μm, the micropores have significant influence on the failure mechanism of the alloy. Meanwhile, at the creep temperature of 125 and 150 ℃, the alloy performs a dimpled transgranular type of failure; at 175 and 200 ℃, the alloy exhibits the characteristics of intergranular failure.
Key words: 2024 aluminum alloy; creep temperature; creep behavior; creep stress; deformation mechanism
