Abstract
When higher corrosion resistance than commercially pure titanium is required, Ti-0.15%Pd alloy is used because of insensitivity to crevice corrosion in NaCl solutions and lower corrosion rate in non-oxidizing acid solutions. Since it has been needed to find out substitute alloys having lower price than Ti-0.15%Pd and comparable corrosion resistance, binary titanium alloys were investigated. Among seventeen elements studied, only Ni and Ru were found to increase corrosion resistance in remarkable manner. Crystallographic analyses showed that most of nickel in a Ti-Ni alloys is precipitated as intermetallic Ti2Ni within α-phase matrix, and the intermetallic compound was found to be effective to bring the corrosion potential into the passive range. However, Ti-Ni alloys are not sufficient in terms of corrosion resistance, if compared with Ti-0.15%Pd alloy. As for Ti-Ru alloys, though they exhibit comparable corrosion resistance to Ti-0.15%Pd alloy, there seemed to have no merit in terms of material cost.
