Oxidation behavior and microstructural evolution of hot-dipped aluminum coating on Ti-6Al-4V alloy at 800 °C

摘要

An aluminized Ti-6Al-4V alloy was prepared successfully by hot-dipping aluminum under a protective argon atmosphere at 800 °C. After isothermal oxidation tests at 800 °C for various times, the weight gain of the hotdipped aluminum coating showed the aluminized coating can provide a significant degree of protection against oxidation at 800 °C. In addition, the coatings of as-coated hot-dipped aluminum and those after being exposed from 1 to 96 h were also evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energydispersive X-ray spectrometer (EDS) analyses as well as Vickers microhardness test. Consequently, the microstructures of the hot-dipped aluminumcoating were found to consist of an outer layer and a multilayer reaction zone.We found that amixture of (Ti,V)Al3 and (Ti,V)Al2 phases exist in the outer layer and that (Ti,V)Al_2, (Ti,V)Al, and (Ti,V)_3Al phases form in sequence within the reaction zone after oxidizing for up to 96 h.