TY - JOUR
T1 - Exploring nanoscale metallic multilayer Ta/Cu films
T2 - Structure and some insights on deformation and strengthening mechanisms
AU - Karpinski, Daniel
AU - Polcar, Tomas
AU - Bondarev, Andrey
N1 - Publisher Copyright:
© 2023
PY - 2024/6
Y1 - 2024/6
N2 - Nanoscale metallic multilayer (NMM) films are systems offering insight into the role of interfaces in metal plasticity, deformation, and strengthening mechanisms. Magnetron sputtering was used to fabricate the Ta/Cu NMM films with a periodicity (equal Ta and Cu layer thickness) from 6 to 80 nm, and with the structure exhibiting immiscible tetragonal β-Ta and face-centred cubic Cu phases. Transmission electron microscopy and X-ray diffraction analyses revealed that, irrespective of the period, all films manifested a polycrystalline structure. The growth direction of both Cu and Ta layers was found to be along 〈001〉 β-Ta || 〈111〉 Cu directions, with the crystallite size constrained by the layer thickness. The studies showed that the Ta/Cu NMMs exhibited compressive residual macro-stress and flow strength, and enhanced elastic recovery at the periodicity of ≤12 nm. Activation volume V⁎ value of 11 to 20 b3 as determined from the indentation creep test under a constant load, may indicate a mixed deformation mechanism. This mechanism likely involves the emission of dislocations from the incoherent Ta/Cu interfaces, as well as the formation of screw dislocations within Cu grains. The high-load indentation test, TEM studies, and the rCLS model collectively demonstrate that all NMM films predominantly undergo plastic deformation. This plastic deformation primarily occurs within the soft Cu layer, while the propagation of dislocations across the incoherent interface is largely excluded.
AB - Nanoscale metallic multilayer (NMM) films are systems offering insight into the role of interfaces in metal plasticity, deformation, and strengthening mechanisms. Magnetron sputtering was used to fabricate the Ta/Cu NMM films with a periodicity (equal Ta and Cu layer thickness) from 6 to 80 nm, and with the structure exhibiting immiscible tetragonal β-Ta and face-centred cubic Cu phases. Transmission electron microscopy and X-ray diffraction analyses revealed that, irrespective of the period, all films manifested a polycrystalline structure. The growth direction of both Cu and Ta layers was found to be along 〈001〉 β-Ta || 〈111〉 Cu directions, with the crystallite size constrained by the layer thickness. The studies showed that the Ta/Cu NMMs exhibited compressive residual macro-stress and flow strength, and enhanced elastic recovery at the periodicity of ≤12 nm. Activation volume V⁎ value of 11 to 20 b3 as determined from the indentation creep test under a constant load, may indicate a mixed deformation mechanism. This mechanism likely involves the emission of dislocations from the incoherent Ta/Cu interfaces, as well as the formation of screw dislocations within Cu grains. The high-load indentation test, TEM studies, and the rCLS model collectively demonstrate that all NMM films predominantly undergo plastic deformation. This plastic deformation primarily occurs within the soft Cu layer, while the propagation of dislocations across the incoherent interface is largely excluded.
KW - Deformation
KW - Magnetron sputtering
KW - Nanoscale metallic multilayers
KW - TEM
UR - http://www.scopus.com/inward/record.url?scp=85191822244&partnerID=8YFLogxK
U2 - 10.1016/j.matchar.2024.113933
DO - 10.1016/j.matchar.2024.113933
M3 - Article
AN - SCOPUS:85191822244
SN - 1044-5803
VL - 212
JO - Materials Characterization
JF - Materials Characterization
M1 - 113933
ER -