Effect of Nickel on the Microstructures of Coating in Hot-Dipped Aluminide Steel

• Published in: Materials and manufacturing processes Vol. 31; no. 9; pp. 1261 - 1268
• Main Authors: Chen, Xiaochun, Peng, Haoping, Su, Xuping, Liu, Ya, Wu, Changjun, Chen, Hairui
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 03.07.2016
• Subjects: Aluminizing; Coating; Diffusion; EBSD; Hot-dipping; SEM; XRD
• ISSN: 1042-6914; 1532-2475
• DOI: 10.1080/10426914.2015.1103862

Hot-dipping aluminizing of 45 steel was carried out in molten Al baths containing 0.0, 1.0, 3.0, and 5.0 wt.% Ni at 710°C for 10, 120, 300, and 600 s. The coatings were analyzed by x-ray diffraction (XRD) and scanning electron microscope (SEM) equipped with energy-dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD). The coating hot-dipped in the Al-5Ni bath consisted of an outer Al-Ni topcoat (α-Al, θ-Al 3 Fe, Al 3 Ni, τ 1 -Al 9 FeNi), minor τ 1 -Al 9 FeNi, minor θ-Al 3 Fe, and major η-Al 5 Fe 2 layers, respectively, while no τ 1 -Al 9 FeNi layer was identified in the coating hot-dipped in the Al-1Ni and Al-3Ni bath. Diffusion path model was introduced to explain this phenomenon. Ni as an alloying element added into Al bath decreased the growth rate of η-Al 5 Fe 2 layer. The average thickness of η-Al 5 Fe 2 layer followed the parabolic law in hot-dipping in the Al-5Ni bath. Also, η-Al 5 Fe 2 had the largest growth rate among the intermetallic layers.