A Study on Thermal Expansion and Thermomechanical Behavior of Composite Metal Foams

Composite metal foams (CMFs) are promising materials for applications requiring high strength and impact resistance, yet their high‐temperature mechanical behavior remains underexplored. This study examines the mechanical performance and coefficient of thermal expansion (CTE) of steel–steel (S‐S) CMFs at temperatures up to 1000 °C. CTE measurements indicate reduced expansion relative to bulk 316L stainless steel, with stable values between 100 and 400 °C, followed by a linear increase up to 1000 °C, indicating S‐S CMF's enhanced thermal stability compared to bulk 316L stainless steel. Quasi‐static compression tests show that S‐S CMFs maintain excellent mechanical performance up to 600 °C, beyond which strength degradation accelerates due to thermal softening, oxidation, and plastic buckling. At 800 °C, the structural integrity of S‐S CMF is significantly compromised, with lateral expansion and energy absorption capacity reduced by over 80%. Scanning electron microscopy (SEM) links the mechanical changes to microstructural evolution, including grain boundary void formation and oxidation at high temperatures. These findings provide the first comprehensive assessment of the thermomechanical behavior of S‐S CMFs, bridging a critical knowledge gap and establishing their operational limits for high‐temperature structural applications.