Thermal modification of ZrCu metallic glass nanolaminates: Structure and mechanical properties

• DOI: 10.48550/arxiv.2407.13272
• Publication Date: 2024-07-18
• Authors: Andrea Brognara; Chanwon Jung; Cristiano Poltron...; P. Djemia; Gerhard Dehm; Matteo Ghidelli; James P. Best
• Keywords: Condensed Matter - Materials Science; Materials Science (cond-mat.mtrl-sci); FOS: Physical sciences

The effects of thermal treatments on metallic glass nanolaminates (NLs), with a composition Zr$_{24}$Cu$_{76}$ and Zr$_{61}$Cu$_{39}$ bilayer period 50 nm, were explored to control their mechanical properties through annealing-induced atomic structure modifications, structural relaxation, partial crystallisation. Annealing up 330 {\deg}C ($T$ < $T_g$, the transition temperature) maintain amorphous NLs, while inducing densification, free volume annihilation, reducing formation corrugations fracture surfaces. Atom probe tomography measurements reveal that annealing at for 60 mins also causes intermixing between layers, altering compositions Zr$_{44}$Cu$_{56}$ Zr$_{55}$Cu$_{45}$ increased mixing enthalpy. Moreover, NLs exhibit superior stability against crystallisation compared monolithic counterparts, remaining 420 {\deg}C, films are crystalline 390 as result chemical interdiffusion heterogeneous NL delaying onset $T$ > $T_g$ ($\sim$420 {\deg}C) induce crystallisation, forming Cu-Zr-based intermetallic Zr-oxide phases, whereas (330 retains visible layer structure. Nanoindentation analyses show progressive increase in elastic modulus hardness higher temperatures relaxation likely nanocrystal formation, maximum equal 7.6 $\pm$ 0.2 GPa obtained after heat treatment exceeding rule-of-mixtures. These results highlight potential tailor structural, NLs.