Effects of laser remelting speeds on microstructure, immersion corrosion, and electrochemical corrosion of arc–sprayed amorphous Al–Ti–Ni coatings

• Published in: Journal of alloys and compounds 2019-01, Vol.771, p.584-594
• Main Authors: Chen, Haixiang, Kong, Dejun
• Format: Article
• Language: English
• Subjects: Aluminum; Arc spraying; Chemical composition; Compressive properties; Corrosion; Corrosion effects; Corrosion mechanisms; Corrosion rate; Corrosion resistance; Corrosion resistant steels; Electrochemical corrosion; Electrode polarization; Emission analysis; Field emission microscopy; Immersion corrosion; Immersion tests (corrosion); Iron; Laser remelting (LR); Melting; Microstructure; Morphology; Nickel coatings; Organic chemistry; Phases; Protective coatings; Residual stress; Substrates; X ray spectra
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2018.08.252

An arc–sprayed amorphous Al–Ti–Ni coating on S355 structural steel was processed using a laser remelting (LR). The surface and cross–section morphologies, chemical compositions, phases and residual stresses of obtained Al–Ti–Ni coatings at the LR speeds of 5, 10, and 15 mm/s were analyzed using a field emission scanning electron microscope (FESEM), energy dispersive spectrometer (EDS), X–ray diffractometer (XRD), and X–ray diffraction stress tester, respectively, and the effects of LR speeds on their immersion corrosion and potentiodynamic polarization curves of Al–Ti–Ni coatings in 3.5% NaCl solution were also investigated to analyze the mechanism of corrosion resistance. The results show that the metallurgical bonding is formed at the Al–Ti–Ni coating interface due to the interdiffusions and recombinations of Al, Ti, Ni, Fe, Cr and Mn. The Al–Ti–Ni coatings at the different LR speeds obtain a certain amount of amorphous phases, which are detected as AlFe, AlFe3, AlCrFe2, Ni2MnAl, and AlNi phases. The residual stresses of as–obtained Al–Ti–Ni coatings at the LR speeds of 5, 10, and 15 mm/s are −12 ± 8, 43.9 ± 3, and −34.4 ± 8 MPa, respectively, of which the tensile residual stress exacerbates the immersion corrosion and the compressive stress restrains the crack expansion. The corrosion potentials of Al–Ti–Ni coatings at the LR speeds of 5, 10, and 15 mm/s are −1.046, −1.106, and −0.986 V, respectively, which shift positively than S355 steel and effectively increase the corrosion resistance of substrate, the electrochemical corrosion resistance of Al–Ti–Ni coating at the LR speed of 15 mm/s is the best among the three kinds of coating. •The compounds of Al-Fe, AlCrFe2 and Ni2MnAl form the metallurgical bonding at the coating interface.•The Al–Ti–Ni coatings after LR are composed of crystal, amorphous and intermetallic compounds.•The Al–Ti–Ni coating at the LR speed of 15 mm/s possesses larger compressive stress, restraining its cracking.•The corrosion potentials of Al–Ti–Ni coatings after LR shift positively, showing high corrosion resistance.