The present study was conducted in order to analyze the microstructure and corrosion resistance of Ti-M (M=Ru, Rh, Pd, Ir, Pt) alloy prepared from titanium and M powders using spark plasma sintering (SPS). The microstructure of SPS’s specimens were observed by scanning electron microscope and X-ray diffraction. Corrosion resistance was determined by measuring the potentiodynamic polarization at a scanning speed of 0.124 V/min using a 5 mass%HCl solution open to air at 25°C. For this measurement, each specimen was scanned beginning at a potential of −1.0 to +2.0 V (SCE), and potential approached noble.
The microstructure observed that the SPS alloys were the particle dispersion type, with added element phases dispersed in the Ti matrix.
Most of the added elements (Ru, Rh, Pd, Pt) formed Ti-M intermetallic compounds on the border between the Ti matrix and added element phase.
Low dispersion of the added element phase reduces the current density in the cathodic area of the SPS alloy polarization curves, and the current density may also decrease if several compounds are generated. Compared to other Ti-M alloys, the current density of Ti-Ir is low because the dispersion is low and that of Ti-Pt is low because several compounds are generated.
Since the active area of the Ti-M (Ru, Rh, Pd, Pt) compound phase is 0 to 1 V (SCE), the compounds increase the current density in the anode area. In the Ti-Pd and Ti-Pt alloys, corrosion marks were observed where the TiPd and TiPt phases were eluded. The Ti-Ir alloy generates no compounds and its current density in the anode area is smaller than those of other Ti-M alloys.
Consideration about Ti-M alloys prepared using SPS is that added element phases are dispersed in the Ti matrix as smaller particles and, moreover, no Ti-M compounds are generated. If Ti-M intermetallic compounds are generated, raising the SPS temperature disperses the compounds into the Ti matrix and reduces the related active area, reducing the corrosion resistance.
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