Processing and performance of HVAF-sprayed Fe-based bulk metallic glass coatings: A sustainable alternative

• Fe–Mo–Cr–P–Al–B BMG alloy adapted for HVAF thermal spraying. • Systematic optimization enabled dense, crack-free, and fully amorphous coatings. • Coating microstructure–property correlations established through wear/corrosion tests. • Optimized coatings showed superior corrosion and comparable wear to cermet. • Sustainable Co-, and W-free coatings for surface protection. Bulk metallic glasses (BMGs) are increasingly recognized as promising materials for surface engineering due to their exceptional hardness, corrosion resistance, and wear resistance, which are critical attributes for components operating in harsh environments. Fe-based BMGs offer a sustainable alternative to conventional coatings that often rely on toxic or scarce raw materials, thus aligning with global environmental and regulatory objectives. This study focuses on a newly developed Fe-based BMG alloy with enhanced glass-forming ability and processability for thermal spray applications. While BMGs exhibit outstanding properties, their limited ductility poses significant processing challenges, including propensity to cracking during deposition. To overcome this, the feasibility of producing dense Fe-based BMG coatings using High Velocity Air Fuel (HVAF) spraying was examined, aiming for superior wear and corrosion resistance. Initial trials resulted in coatings with severe cracking, delamination, and poor adhesion. However, systematic manipulation of spray parameters led to coatings with markedly reduced cracking, improved adhesion, and enhanced microstructural integrity. Comprehensive characterization included microstructure, amorphicity, and hardness examination, complemented by wear and corrosion performance assessments. The promising results represent a critical step toward establishing Fe-based BMGs as viable and environmentally friendly coating solutions via HVAF thermal spraying.