CREEP BEHAVIOR OF Al-Cu-Mg-Ag HEAT-RESISTANT ALLOY AT ELEVATED TEMPERATURE

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 degrees C 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 degrees C/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 degrees C keep a relatively lower level, but increases to a high level when the creep temperature increased to 180 degrees C. 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.