Defect-driven Microstructural Evolution and Mechanical Characterization of Complex Concentrated Alloy Thin Films
Please login to view abstract download link
Complex concentrated alloy thin films (CCA-TFs) are studied for their ability to combine mutually exclusive properties like strength, ductility. CoCrNi TFs films exhibit high hardness (~9 GPa) and yield strength (~3.4 GPa) due to their columnar structure with planar defects [1]. The addition of Fe stabilizes FCC phase, reducing grain size ~20 nm and increasing hardness ~10 GPa. However, the relationship between CCA composition, microstructural evolution and mechanical behaviour remains unclear, while a thin film nanoengineered approach, based on the control and evolution of chemical heterogeneity and phase structure, aimed to boost mutually exclusive mechanical mechanical properties by developing new nanostructures is still an open field. This study focuses on CoCrNi, Fex(CoCrNi)100-x CCA-TFs synthesized by magnetron sputtering, varying Fe from 13 to 29 at.%. CoCrNi CCA-TF displayed a columnar structure with dual FCC-HCP phase, high density of stacking faults and twinning, resulting in H=9.7 GPa, E=204.4 GPa. Adding Fe stabilized the FCC phase with fewer defects, reducing H and E to 7.6 GPa and 185 GPa, respectively, owing to a higher stacking fault energy (32.5 mJ m−2) [2]. Based on previous results, we fabricated CoCrNi/Fe (FCC/BCC) nanolaminates with bilayer periods (Ʌ) of 70, 35, and 20 nm. They showed high adhesion and improved H, while micropillar compressions revealed high yield strengths (2.8 GPa) and plasticity ~40% upon reducing Ʌ to 20 nm. This results from blocking dislocations and crack propagation at the interfaces. Overall, this study shed light on the understanding of composition-microstructure-mechanical property relationship in CoCrNi and Fex(CoCrNi)100-x, and CoCrNi/Fe nanolaminate CCA-TFs.
complas_sec@cimne.upc.edu/ Telf. + 34 - 93 405 46 94
Copyright © 2024 CIMNE, All Rights Reserved. Terms of service