Macro-Micro Relationship of Dimensional Changing Behavior of Aluminum Matrix Composite

Accuracy and stability have always been the eternal pursuit of inertial navigation. Among them, the dimensional stability of inertial instrument materials is a key factor in determining the accuracy level of equipment. The dimensional changing(DC) behavior is a material problem extracted from the common accuracy drift problem in engineering technology. The DC behavior of 45vol% SiC P /2024Al composite under no load at constant temperature was systematically studied in-depth using in-situ heating XRD and double Cs-corrected transmission electron microscopy. The trend and magnitude of lattice constant and strain mapping of matrix near SiC/Al interface were both tracked and examined. A high-resolution thermal dilatometer was used to measure the macroscopic DC. Thermal mismatch residual stress has a decisive effect on the DC of SiC P /2024Al composite. The effect of exsolution on the DC of SiC P /2024Al composite was also discussed. Different dominant mechanism of DC between aluminum alloy and composites leads to the difference in the magnitude, rate, and stabilization of the dimensional change. In order to verify the validity of the mechanism, the DC results of different matrix and different heat treatment states were compared and explained. The estimation method of DC based on the volume change of unit cell could accurately predict the trend of DC and the magnitude of SiC P /2024Al composite. This provides instructive guidance for deeply understanding the DC behavior of aluminum matrix composites, and enriches the research work of micro-plastic deformation.