Development and comprehensive characterization of lightweight high-performance LECA-based Hybrid Metal Foams

Abstract This study provides a comprehensive characterization of advanced lightweight Hybrid Metal Foams (HMFs) based on Lightweight Expanded Clay Aggregate (LECA) particles. The investigation includes detailed microstructural analysis and mechanical property evaluation to elucidate the matrix-dependent behavior of the newly developed HMFs. All HMFs display a dense matrix-LECA interface, with AlSi7Mg-HMF featuring a thin Mg-enriched interface, while AlSi12 and Al99.5 HMFs present typical elemental transitions. The results show that the AlSi7Mg-HMF outperforms AlSi12 and Al99.5, highlighting significant matrix effects on compressive properties. The HMFs exhibit distinct behaviors, with AlSi7Mg and Al99.5 matrices displaying a strain hardening plateau, whereas AlSi12-HMF shows strain softening during compression. Furthermore, the alloyed matrices (AlSi7Mg and AlSi12) fail through brittle shear band fractures, while the non-alloyed Al99.5 matrix undergoes ductile deformation, characterized by a barrel-shaped collapse without cracking. Notably, the AlSi7Mg-HMF sets a new performance benchmark for metal foams with densities below 1.6 g/cm 3 . These findings underscore the critical influence of matrix composition on the compressive behavior and failure mechanisms of HMFs. The results contribute to the understanding of these advanced materials, offering a foundation for their further optimization in engineering applications.