Substrate Bias Dependent Microstructure and Properties of TC17 Titanium Alloy Coatings Deposited by Magnetron Sputtering

Abstract

While matrix coated fiber method is used to fabricate SiC continuous fiber reinforced TC17 (Ti-5Al-2Sn-2Zr-4Mo-4Cr) matrix composites (SiCf/TC17), the properties of SiCf/TC17 composite are strongly affected by the microstructure and properties of TC17 alloy coatings in precursor wires. In this work, Vb(substrate bias) was adopted to tailor the microstructure and properties of TC17 coatings, and Vb dependent on microstructure, morphology, composition, stress, hardness and adhesion for TC17 coatings have been investigated by X-ray diffraction, scanning electron microscope, atomic force microscope, auger electron spectrometer, surface profiler and nanoindenter. The experimental results showed that all coatings crystallized with hexagonal structure (α-Ti). The migratory ability of incoming ions increased with increasing Vb from floating to-120V, and the smoothing growth surface and re-sputtering came into prominence with further increasing Vb, then the surface roughened again and accompanied by a transition of growth mode from column grains to compact-grain structures. As Vb increased, Al content increased while Ti content decreases. In addition, compressive stress and hardness showed a rising trend caused by ions implantation. Interface ions implantation and stress state acted together on the adhesive force between TC17 alloy coatings and SiC fiber.