Abstract:Single phase β-(Ni, Pt)Al coating was prepared on the surface of nickel-based single crystal superalloy substrate with different thickness via electroplating Pt and gaseous aluminizing. The microstructure evolution and element interdiffusion behavior between coating and substrate during thermal exposure at 1100 ℃ for 200 h were characterized by scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and electron probe micro-analyze (EPMA). The results show that there is no significant difference in the cross-sectional morphologies of the PtAl coating/superalloy samples with different substrate thickness (0.8 mm, 1.0 mm and 1.3 mm) after thermal exposure at 1100 ℃ for 200 h. Secondary reaction zone (SRZ) containing topological close packed phases (TCP) is formed behind the interdiffusion zone (IDZ). The thickness of the SRZ for the samples with substrate thickness of 0.8 mm, 1.0 mm and 1.3 mm were 37 μm, 35 μm, 34 μm, respectively. There was no significant difference in the composition profiles of the samples with different substrate thickness during thermal exposure for 200 h. During the thermal exposure process, the internal diffusion of Pt and Al from the coating to the substrate is accompanied with the external diffusion of Ni, Co, Cr and Ru.
