Effects of ion-plasma treatment temperature of the aluminium coating on the structure and phase composition of the VT6 titanium alloy

Abstract

In this study, we studied the effects of aluminum coating treatment temperature on the microstructure and phase composition when applied to a VT6 titanium alloy substrate within a low-pressure arc discharge plasma environment. The ion-plasma treatment was conducted at 450 and 500 °C, employing argon shielding, while the aluminum coating was deposited using the vacuum-arc process, resulting in a coating thickness of ~3 μm. Microstructural analysis was performed using a scanning electron microscope, and the structural and phase composition were examined using X-ray diffraction (XRD) imaging in symmetric imaging mode with CuKα radiation. Our findings demonstrate that the application of the aluminum coating initiates the formation of a near-surface α-stabilized layer, extending up to 2.5 μm in thickness due to the heat generated during the ion cleaning process. Subsequent ion-plasma treatment further results in the development of a TiAl3 intermetallide site, reaching thicknesses of up to 1.5 μm, while the α-stabilized region expands to 5.5 μm. Higher temperatures during the treatment process contribute to an increase in the thickness of these aforementioned layers and also lead to the emergence of an intermediate TiAl intermetallic layer.