材料期刊网

在100-210℃和150-300 MPa的条件下, 研究了Al-5.3Cu-0.8Mg-0.5Ag-0.3Mn-0.15Zr耐热铝合金的蠕变行为, 探讨了时效状态对合金高温性能的影响. 结果表明: 在相同蠕变条件下, 欠时效态合金的稳态蠕变速率远远低于峰时效态合金. 在210℃/200 MPa下, 欠时效态合金的蠕变断裂时间为75 h, 而峰时效态合金的蠕变断裂时间仅为21 h. 蠕变过程中, 合金中的析出相长大. 峰时效态合金中析出相尺寸的增大速率高于欠时效态合金. 欠时效态合金中还发生了动态析出, 这些细小的析出相在蠕变过程中阻碍了位错的运动, 使得合金蠕变速率降低. 在100-150℃下合金的稳态蠕变速率保持在较低水平. 当温度升高到180℃时, 合金的稳态蠕变速率急剧增大. 合金稳态蠕变速率随着蠕变温度的升高和应力的提高均有增大趋势, 3者之间的关系可用一本构方程来表示, 其表观激活能为102 kJ/mol.

The creep behaviors of heat--resistant alloy Al-5.3Cu-0.8Mg-0.5Ag-0.3Mn-0.15Zr (Al-Cu-Mg-Ag) were studied in a temperature range of 100-210℃ and a load range of 150-300 MPa, and the effect of aging on the properties of Al-Cu-Mg-Ag alloy at elevated temperatures was also investigated. The results show that the steady creep rate of the under-aged alloy is much lower than that of the peak--aged alloy at the same creep conditions. The creep fracture time is 75 h for the under-aged Al-Cu-Mg-Ag alloy at 210℃/200 MPa, while that for the peak-aged alloy is only 21 h. The precipitates grow gradually during the creep process and the growth rate in the peak-aged alloy is higher than that in the under-aged alloy. Dynamic precipitation happened in the under-aged alloy. The fine precipitates inhibite the motion of the dislocations during the creep, which leads to lower creep deformation rate compared to the peak-aged alloy. The steady creep rates of the under-aged Al-Cu-Mg-Ag alloy at 100-150℃ keep a relatively lower level, but increases to a high level when the creep temperature increased to 180℃. The steady creep rate increased with increasing temperature or stress, which can be described by a constitutive equation with an apparent activation energy of 102 kJ/mol.