Elevated Temperature Mechanical Property Degradation of AA7475 Aluminum Alloy: In Situ Microstructure Analysis

The present investigation focuses on the real-time development of grain boundary precipitates during thermal ageing and their influence on the mechanical properties of AA 7475 as a function of temperature. A series of uniaxial tension tests were conducted at different temperatures to estimate the degradation of mechanical properties. An in situ heating transmission electron microscopy (TEM) experiments were conducted at the range of temperatures to capture the real-time precipitation. The process of Guinier–Preston (GP) zone formation to the transformation of T^′ precipitates is captured in the temperature range of room temperature (RT) to 350 °C. The formation and coarsening of precipitates within the grain and grain boundary with increase in temperature reduces the yield, ultimate, and total elongation. Electron backscatter diffraction (EBSD) was employed on deformed samples to understand the microstructure evolution. The results shows an increasing trend in the low-angle grain boundary (LAGB) fraction within the temperature range of RT to 250 °C, followed by a decreasing trend with further increase in temperature.