Ref.: MmeFsu17-004
Apresentador: Haroldo Cavalcanti Pinto
Autores (Instituição): Pereira, J.(Universidade de São Paulo); Ott, V.(Karlsruhe Institute of Technology); Afonso, C.R.(Universidade Federal de São Carlos (UFSCar)); De Sousa Malafaia, A.(Universidade Federal de São João del Rei); Stueber, M.(Karlsruhe Institute of Technology); Greiner, C.(Karlsruhe Institute of Technology); Moreto, J.A.(Universidade de São Paulo); Pinto, H.C.(Escola de Engenharia de São Carlos da Universidade de São Paulo);
Resumo:
Nanocrystalline thin films are widely used due to their excellent mechanical strength and resistance to wear. However, one of the main challenges lies in preventing undesirable grain growth, especially at high temperatures, which increases the overall energy of the system due to the larger grain boundary volume. To address this issue, it is crucial to determine the optimal conditions for heat treatment and to select the appropriate chemical composition to stabilize the grain boundaries. In this study, we investigated the grain growth and phase changes in Ti-Cr-Zr magnetron-sputtered nanoscale multilayers with individual layer thicknesses of 5 and 10 nm, subjected to vacuum heat treatment at 1100 °C for 5 and 10 minutes. The characterization techniques included X-ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction (XRD), and Transmission Electron Microscopy (TEM). During the deposition process, evidence of diffusion was observed, resulting in the formation of Cr4TiZr, TiCr2, and Cr2Zr phases in the multilayers. Additionally, the nanoscale multilayers with 10 nm individual layer thickness exhibited the emergence of the Ti0.3Zr0.7 phase. Subsequent heat treatment led to grain growth, with an average grain size of 173.7 nm and 119.1 nm observed after 10 minutes for the multilayers with 5 nm and 10 nm individual layer thickness, respectively. The different growth rates can be attributed to the distinct interfacial volumes, which influence the reaction velocity due to variations in the nano-layer thickness. No new phases were formed after heat treatment in the case of the 10 nm individual layer thickness coating. However, the 5 nm individual layer coatings showed the emergence of the Ti0.3Zr0.7 phase, which was not present after deposition. In conclusion, this research successfully achieved nano grain stabilization of the Ti-Cr-Zr system nanoscale multilayers after heat treatment at 1100 °C for 10 minutes. This process resulted in the complete decomposition of the multilayer structure, leading to the formation of grains smaller than 200 nm, representing a significant advancement in the control of grain growth in nanocrystalline materials.