Combinatorial Study of Phase Composition, Microstructure and Mechanical Behavior of Co-Cr-Fe-Ni Nanocrystalline Film Processed by Multiple-Beam-Sputtering Physical Vapor Deposition

Abstract

A combinatorial Co-Cr-Fe-Ni compositional complex alloy (CCA) thin film disk with a thickness of 1 µm and a diameter of 10 cm was processed by multiple-beam-sputtering physical vapor deposition (PVD) using four pure metal sources. The chemical composition of the four constituent elements varied between 4 and 64 at.% in the film, depending on the distance from the four PVD sources. The crystal structure, the crystallite size, the density of lattice defects (e.g., dislocations and twin faults) and the crystallographic texture were studied as a function of the chemical composition. It was found that in a wide range of elemental concentrations a face-centered cubic (fcc) structure with {111} crystallographic texture formed during PVD. Considering the equilibrium phase diagrams, it can be concluded that mostly the phase composition of the PVD layer is far from the equilibrium. Body-centered cubic (bcc) and hexagonal-close packed (hcp) structures formed only in the parts of the film close to Co-Fe and Co-Cr sources, respectively. A nanocrystalline microstructure with the grain size of 10–20 nm was developed in the whole layer, irrespective of the chemical composition. Transmission electron microscopy indicated a columnar growth of the film during PVD. The density of as-grown dislocations and twin faults was very high, as obtained by synchrotron X-ray diffraction peak profile analysis. The nanohardness and the elastic modulus were determined by indentation for the different chemical compositions on the combinatorial PVD film. This study is the continuation of a former research published recently in Nagy et al., Materials 14 (2021) 3357. In the previous work, only the fcc part of the sample was investigated. In the present paper, the study was extended to the bcc, hcp and multiphase regions.

Machine Learning-Based Characterization of the Nanostructure in a Combinatorial Co-Cr-Fe-Ni Compositionally Complex Alloy Film

“…As an example, Figure 2a shows an XRD pattern from the FCC+(HCP) region. It should be noted that, in our former publications, this region was a part of the single phase FCC area, since the broad peaks were included in the background for the points where CMWP evaluation was performed [11,15]. In the present case, the FCC and FCC+(HCP) regions are separated since the new ML-XLPA method was developed only for single phase FCC structures.…”

“…In our previous works [11,15], a phase map of the presently studied Co-Cr-Fe-Ni CCA sample was determined, which is also presented here in Figure 1. HCP and BCC indicate hexagonal close-packed and body-centered cubic structures, respectively.…”

“…is the position of the jth peak and α j is its intensity. Further microstructural parameters such as the effective cut-off radius of dislocations (R e * ) and the two quantities q and C h00 describing the average contrast factor (C hkl ) were fixed to specific values since these parmeters do not change significantly in the different locations investigated by the CMWP method in our former works [11,15]. Thus, in the present study, the values of R e * , C h00, and q were fixed to 8 nm, 0.31, and 2.1, respectively.…”

“…These positions are shown in Figure 1. The microstructural parameters obtained in these points using CMWP have already been listed in our former publication [15]. The error of the predicted parameters was esti- The parameter maps obtained by ML-XLPA were compared in six positions to the parameters acquired through CMWP pattern fitting.…”

“…These positions are shown in Figure 1. The microstructural parameters obtained in these points using CMWP have already been listed in our former publication [15]. The error of the predicted parameters was estimated from the difference between the predicted values obtained for different positions where CMWP yielded identical or near-identical parameter values.…”