Beyond Fundamental Building Blocks: Plasticity in Structurally Complex Crystals

TL;DR

This paper investigates how deformation behavior in intermetallic crystals can be predicted based on their fundamental building blocks, revealing complex plasticity mechanisms influenced by local bonding environments.

Contribution

It demonstrates that while elastic properties follow simple rules, plastic deformation in complex intermetallics depends on stacking and bonding, advancing understanding of their mechanical behavior.

Findings

Elastic properties follow a rule of mixtures

Plastic deformation mechanisms are influenced by stacking and bonding

Local bonding environments are crucial for predicting behavior

Abstract

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. We investigate SmCo$_2$ and SmCo$_5$ as fundamental building blocks and compare them to the structurally related SmCo$_3$ and Sm$_2$Co$_{17}$ phases. Nanoindentation and micropillar compression tests were performed to characterize the primary slip systems, complemented by generalized stacking fault energy calculations via atomic-scale modeling. Our 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.