Microstructures, mechanical properties and corrosion resistance of the ZrxTi (Ag) alloys for dental implant application

The ZrxTi (Ag) alloys were designed for the application of dental implants. The microstructures of Zr20Ti and Zr40Ti alloy were observed using optical microscope and transmission electronic microscope. The hardness and compressive tests were performed to evaluate the mechanical properties of the ZrxTi alloys. The electrochemical behavior of the ZrxTi alloys with and without 6% Ag was investigated in the acidified artificial saliva containing 0.1% NaF (pH = 4). For comparison, the electrochemical behavior of cp Ti was examined in the same condition. The results show that the quenched Zr20Ti and Zr40Ti alloy exhibit acicular martensite microstructures containing twin substructure. They display good mechanical properties with the hardness of ∼330HV, the yield strength of ∼1000 MPa and the strain to fracture of ∼25% at room temperature. Adding 6% Ag to Zr20Ti alloy enhances the passivity breakdown potential and the self-corrosion potential, but hardly affects the corrosion current density and the impedance modulus. 6% Ag in Zr40Ti alloy distinctly increases pitting corrosion resistance, which is attributed the formation of thick, dense and stable passive film under the joint action of titanium and silver. In comparison with cp Ti, Zr40Ti6Ag alloy possesses the same good corrosion resistance in the rigorous oral environment as well as the superior mechanical properties.