Ideal strength and mechanical properties of thin copper films: A DFT study

Abstract

This study utilizes density functional theory simulations to investigate the mechanical properties and ideal strength of thin Cu(001) films. The Cu(001) slab exhibits structural instability when subjected to uniaxial tensile strain, which is evidenced by a notable stress drop. The mechanical strength and behavior of these films are influenced by several factors, including film thickness, internal atomic arrangement, and the presence of impurities. Specifically, thinner Cu(001) slabs exhibit a reduction in ideal strength and display unique local strain patterns, such as compressive stress along the interior in-plane direction. Variations in atomic configurations, particularly in bridge and top arrangements, lead to significant declines in mechanical performance, a trend that is similarly observed in Cu/Ni structures. The incorporation of impurities, such as C and N, into the octahedral sites markedly enhances the strength of the slab, indicating that atomic-level modifications can improve the mechanical properties of Cu films. These findings contribute to the advancement of Cu films with optimized mechanical performance for high-performance applications.