Effects of Al/Ti Additions on the Corrosion Behavior of Laser-Cladded Hastelloy C276 Coatings

Résumé fourni par la source

This study investigates the effects of aluminum (Al) and titanium (Ti) additions on the porosity, microstructure, and corrosion performance of Hastelloy C276-based coatings fabricated via laser cladding on nodular cast iron substrates. Nickel-based alloy powders blended with varying Ti (1–10 wt.%) and Al (0.5–2.5 wt.%) contents were deposited under optimized laser parameters. Microstructural characterization revealed that Ti addition refined the grain structure and promoted the formation of TiC phases, while Al addition dispersed eutectic networks into isolated island-like structures. Both elements effectively suppressed porosity by reducing gas entrapment during solidification. However, excessive Ti (10 wt.%) induced brittle fracture due to TiC agglomeration, and Al addition caused interfacial cracks owing to Al2O3 formation. Electrochemical tests in a 3.5 wt.% NaCl solution indicated that Al/Ti additions enhanced initial passivation but reduced corrosion resistance due to weakened oxide film stability. XPS analysis revealed that Al-enriched coatings formed Al2O3 and Al(OH)3, whereas Ti-modified coatings developed TiO2 and TiC, both influencing the passivation behavior. These findings provide critical insights into tailoring laser-clad coatings for marine applications by balancing porosity suppression and corrosion resistance.

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