Degradation law of high-temperature mechanical properties of aluminum powder metallurgical structural components for aerospace applications

The mechanical properties of aluminum powder metallurgical structural components used in aerospace will degrade over time under high temperature environments, mainly reflected in changes in key indicators such as strength, plasticity, and fracture toughness.

In the early stage of high temperature, the strength of structural components will decrease to a certain extent. This is because high temperature activates atomic diffusion in the aluminum matrix, leading to increased grain boundary slip and dislocation movement, and the microstructure begins to evolve, resulting in a decrease in the material's ability to resist external forces. At the same time, plasticity will also change, generally manifested as a slight increase followed by a sustained decrease. In the initial stage, high temperature may release the internal stress of the material to a certain extent, and the plasticity of local areas may slightly increase. However, as time goes on, the microstructure deteriorates such as grain growth and coarsening of precipitated phases, leading to a significant decrease in plasticity.

As the exposure time to high temperature is further prolonged, the fracture toughness will also significantly decrease. Microscopic defects within the material, such as micropores and microcracks, continuously expand and connect under the combined action of high temperature and stress, forming macroscopic cracks. The resistance to crack propagation decreases, making it possible for structural components to fracture at lower stresses.

In addition, the degradation rate is not constant, and there may be acceleration stages in specific temperature ranges. This is mainly related to the key stages of microstructural evolution, such as the dissolution and recrystallization of second phases, which accelerate the degradation of mechanical properties. Understanding the degradation laws of high-temperature mechanical properties is crucial for the design, material selection, and life assessment of aluminum powder metallurgical structural components in the aerospace field, which helps ensure the safe and reliable operation of aircraft in high-temperature environments.