Beyond Fundamental Building Blocks: Plasticity in Structurally Complex Crystals

Intermetallics, which encompass a wide range of compounds, often exhibit similar or closely related crystal structures, resulting in various intermetallic systems with structurally derivative phases. This study examines the hypothesis that deformation behavior can be transferred from fundamental building blocks to structurally related phases using the binary samarium-cobalt system. SmCo₂ and SmCo₅ are investigated as fundamental building blocks and compared them to the structurally related SmCo₃ and Sm₂Co₁₇ phases. Nanoindentation and micropillar compression tests are performed to characterize the primary slip systems, complemented by generalized stacking fault energy (GSFE) calculations via atomic-scale modeling. The results show that while elastic properties of the structurally complex phases follow a rule of mixtures, their plastic deformation mechanisms are more intricate, influenced by the stacking and bonding nature within the crystal's building blocks. These findings underscore the importance of local bonding environments in predicting the mechanical behavior of structurally related intermetallics, providing crucial insights for the development of high-performance intermetallic materials.