Plastic Deformation Modes of CuZr/Cu Multilayers

Abstract

We synthesized CuZr/Cu multilayers and performed nanoindentation testing to explore the dependence of plastic deformation modes on the thickness of CuZr layers. The Cu layers were 18 nm thick and the CuZr layers varied in thickness from 4 nm to 100 nm. We observed continuous plastic co-deformation in the 4 nm and 10 nm CuZr − 18 nm Cu multilayers and plastic-induced shear instability in thick CuZr layers (>20 nm). The plastic co-deformation is ascribed to the nucleation and interaction of shear transformation zones in CuZr layers at the adjacent interfaces, while the shear instability is associated with the nucleation and propagation of shear bands in CuZr layers. Shear bands are initialized in the CuZr layers due to the accumulated glide dislocations along CuZr-Cu interfaces, and propagate into adjacent Cu layers via slips on {111} plane non-parallel to the interface. Due to crystallographic constraint of the Cu layers, shear bands are approximately parallel to {111} plane in the Cu layer.

Thickness Effect of Nanocrystalline Layer on the Deformation Mechanism of Amorphous/Crystalline Multilayered Structure

“…Therefore, several studies have been proposed to understand the mechanically deformation of metallic glass. Shear band is the main cause of mechanical deformation in metallic [Feng, Wang, Pan et al (2015); Zhang, Li and Li (2017); Cui, Abad, Wang et al (2016)]. Plastic deformation is produced by shear band propagation and initiation in ductile manner metallic glass [Feng, Wang, Pan et al (2015); Zhang, Li and Li (2017); Cui, Abad, Wang et al (2016)].…”

Interface-Related Shear Banding Deformation of Amorphous/Crystalline CuZr/Cu Nanolaminates by Molecular Dynamics Simulations

“…Inserting a soft crystalline phase into the amorphous phase was recently found to be an effective method to resolve this issue. Numerous experimental ndings [1][2][3][4][5][6][7] and molecular dynamics (MD) studies [8][9][10] had revealed a combination of high strength and good ductility in nanoscaled amorphous/crystalline nanolaminates (A/CNLs). The enhanced strength was attributed to both of the two constituent metallic layers 11) , and the better plastic deformability was induced from the easily strain-accommodated amorphous/crystalline interface (ACI).…”

“…The shear banding deformation of A/CNLs was also closely linked to the microstructures of nanocrystalline layers. For example, shear bands (SBs) in CuZr/Cu A/CNLs were initialized in CuZr layers due to accumulated glide dislocations along CuZr-Cu interfaces, and then propagated into adjacent Cu layers via slips on (111) plane non-parallel to the interface 6,16) . That is, due to crystallographic constraint of the Cu layers, SBs were approximately parallel to (111) plane in the Cu layer.…”

“…That is, due to crystallographic constraint of the Cu layers, SBs were approximately parallel to (111) plane in the Cu layer. Actually, nanocrystalline grains synthesized by magnetron sputtering typically grow with columnar morphology along the deposition growth direction 17,18) , and contain highly distributed defects such as pre-storage dislocations, grain boundaries (GB) and nanoscale twin boundaries (TB) 6,[19][20][21] . GB planar defects consisting of a group of dislocations often play crucial roles in the mechanical behavior of nanocrystalline metals 22) .…”

Deformation mode transitions in amorphous-Cu45Zr55/crystalline-Cu multilayers

“…To delineate these factors in MG composites, the amorphous-crystalline multilayered structure presents a model system. The use of multilayers allows for a controlled growth of crystalline and amorphous phases and thus a systematic study of deformation behaviors [7][8][9][10][11]. Recent studies on such amorphous/nanocrystalline (e.g., CuZr/Cu) multilayers have revealed that when the layer thickness is carefully tuned, a multilayer structure can suppress the formation of catastrophic shear bands and enable plastic co-deformation of the two phases.…”