Optimization of Sputtering Process for Medium Entropy Alloy Nanotwinned CoCrFeNi Thin Films by Taguchi Method

Area of Science:

• Materials Science
• Thin Film Deposition
• Alloy Engineering

Background:

• Medium entropy alloys (MEAs) offer tunable properties for advanced applications.
• Pulsed direct current (DC) magnetron sputtering is a key technique for thin film fabrication.
• Optimizing deposition parameters is crucial for achieving desired MEA thin film characteristics.

Purpose of the Study:

• To systematically optimize the properties of CoCrFeNi MEA thin films.
• To identify the ideal deposition parameters for pulsed DC magnetron sputtering.
• To achieve low electrical resistivity, low surface roughness, and high hardness in the thin films.

Main Methods:

• Utilized pulsed DC magnetron sputtering for thin film deposition.
• Employed energy dispersive X-ray spectroscopy (EDS), X-ray diffractometry (XRD), and transmission electron microscopy (TEM) for characterization.
• Applied the Taguchi experimental method and analysis of variance (ANOVA) to optimize five deposition parameters: substrate bias, temperature, working pressure, rotation speed, and pulsed frequency.

Main Results:

• Identified optimal deposition parameters yielding low electrical resistivity (98.2 ± 0.8 μΩ·cm).
• Achieved low surface roughness (0.5 ± 0.1 nm) and high hardness (9.3 ± 0.2 GPa).
• Observed abundant nanotwins and dual face-centered cubic-hexagonal close-packed (FCC-HCP) phases in some specimens.

Conclusions:

• The Taguchi method and ANOVA effectively optimized CoCrFeNi MEA thin film properties.
• Optimized deposition parameters significantly enhance electrical and mechanical characteristics.
• The findings provide a pathway for fabricating high-performance CoCrFeNi MEA thin films.