Influence of Laser Power on CoCrFeNiMo High-Entropy Alloy Coating Microstructure and Properties

Area of Science:

• Materials Science
• Metallurgical Engineering
• Surface Engineering

Background:

• Conventional methods for fabricating high-entropy alloy (HEA) coatings often suffer from porosity and impurity issues.
• CoCrFeNiMo HEA coatings are promising for demanding applications due to their unique properties.

Purpose of the Study:

• To optimize the fabrication of CoCrFeNiMo HEA coatings using coaxial powder-fed laser cladding.
• To investigate the effects of laser power on microstructure, hardness, wear, and corrosion resistance.
• To address porosity and impurity challenges inherent in traditional coating methods.

Main Methods:

• Fabrication of CoCrFeNiMo HEA coatings via coaxial powder-fed laser cladding.
• Systematic variation of laser power from 1750 W to 2500 W.
• Microstructural analysis, hardness testing, wear testing, and electrochemical corrosion testing in 3.5 wt.% NaCl solution.

Main Results:

• All fabricated HEA coatings exhibited eutectic/hypereutectic microstructures.
• Laser power of 2250 W optimized the microstructure, resulting in a dual-phase structure (FCC matrix with dispersed σ phases).
• The optimized coating achieved exceptional hardness (738.3 HV0.2), an ultralow wear rate (4.55 × 10-5 mm3/N·m), and minimal corrosion current (2.31 × 10-4 A/cm2).

Conclusions:

• Coaxial powder-fed laser cladding is an effective method for producing high-quality CoCrFeNiMo HEA coatings.
• Optimized laser power (2250 W) is crucial for achieving superior mechanical and corrosion properties.
• The study provides insights into the friction and galvanic corrosion mechanisms of the CoCrFeNiMo HEA coating.