Microstructure and corrosion behavior in SBF medium of spark plasma sintered Ti-xZr-20Si-10B (x=5, 7, 10, 15, 20 at.-%) alloys

摘要

This work aims to evaluate the microstructure and corrosion behavior in SBF medium of spark plasma sintered Ti-xZr-20Si-10B (x = 5, 7, 10, 15 and 20 at.-%) alloys. Metastable Ti-Zr-Si-B (at.-%) powders previously prepared ball milling for 600min were used as starting materials. Spark plasma sintering (SPS) of mechanically alloyed Ti-Zr-Si-B powders was performed under controlled atmosphere at 1100 degrees C for 12 min using 20 MPa in order to obtain cylindrical bodies with 10mm diameter. SPS samples were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry, and corrosion tests. The electrochemical corrosion behavior of these alloys was evaluated in electrolytic solution 1.5 SBF (Simulated Body Fluid) at 36.5 degrees C and pH 7.4 by means of open circuit potential (OCP) measurements and potentiodynamic polarization tests. SPS process produced dense and homogeneous samples. Despite the short sintering time, the Ti-Zr-Si-B alloys presented near-equilibrium and homogeneous microstructures. Ti6Si2B dissolving between 6.6 and 8.3 at.-% Zr was formed in the quaternary alloys with 5 and 7 at.% Zr, respectively. In detrimental to its formation, the Ti3Si phase was preferentially formed in the SPSed alloys with 10, 15 and 20 at.-% Zr, dissolving between 11.2 and 15.4, 16.9-24, and 20.6-25.3 at.-% Zr, respectively. No transpassive domain was noted in the Ti-15Zr-20Si10B alloy at higher potentials after the passive layer break occurred around the 1.44 V, which presented pits on its corroded surface in SBF medium. SPSed Ti-7Zr-20Si-10B alloy exhibited better corrosion resistance in SBF medium than the Ti pure and Ti-6Al-4V alloy. (C) 2019 Elsevier B.V. All rights reserved.