Devitrification and sliding wear behaviors of AlFeSi metallic glass coatings

Thermally-induced structure evolutions and wear behaviors of the AlFeSi metallic glass coatings were investigated. Annealing below the onset crystalline temperature, the microstructure of the coating consists of the amorphous phase coexistence with α-Al crystals. The partially devitrified annealing (350 °C) promotes new Al9Fe2Si2 and Al9FeSi3 phases precipitations. The fully crystallized annealing (≥400 °C) produces three crystalline phases of α-Al, Al9Fe2Si2, and Al9FeSi3. The hardening responses of the coatings depend on the annealing temperature. Under dry friction conditions, wear rates of the full crystallization coatings are lower than that of the partial crystalline and as-sprayed coatings. The wear resistance of the coating annealed at 450 °C is about 4 times that of the as-sprayed coating. In 3.5wt.% NaCl solution, current density induced by sliding wear increases as a function of the annealing temperature. The as-sprayed coating displays excellent resistance to tribocorrosion. The microstructural evolutions responsible for annealing-induced changes in wear behaviors are discussed.