Thermodynamic Structural Stability and Polarization Behavior of Cast Amorphous Alloy

Abstract

The thermodynamic structural stability and anodic polarization behavior in Hanks' solution of cast amorphous Zr 65 Al 7:5 Ni 10 Cu 17:5 alloy rods with a diameter of 2.0 mm and 2.5 mm and a length of 35 mm were evaluated. The change of the magnitude of the super-cooled liquid region owing to structural relaxation was obtained from the differential scanning calorimetry (DSC) curve. Since the super-cooled liquid region of the distant region from the sprue of mold was larger than that of the proximate region to the sprue, the structural stability was lower in the distant region than in the proximate region. It was revealed that the structural stability varies along the distance from the sprue. In electrochemical analysis in a simulated body fluid, the specimens sampled from the distant region showed higher open-circuit potential, lower passive current density, and lower pitting potential than those from the proximate region. In other words, the amorphous structure with low stability shows higher passivity but lower pitting corrosion resistance than that with high stability. Consequently, the corrosion behavior of zirconium-based amorphous alloy sensitively depends on the structural stability in a biological environment.

Fabrication and corrosion behavior of Ti-based bulk metallic glass composites containing carbon nanotubes

“…Therefore, pits of corrosion are distinct. Morrison et al [15] and Hiromoto et al [16] reported that the defects of the passive film on the specimen surface due to these inhomo- Table 1 Polarization results of Ti50Cu28Ni15Sn7 bulk metallic glasses containing CNT mixed for 8 h in Hanks' solution at 310 K. geneities serve as active sites for chloride ion attack and result in penetration of the passive film. The susceptibility to localized corrosion of BMG has been shown to increase with increasing concentrations of chloride ions in the Ti-based and Zr-based system.…”

In Vivo Evaluation of Bulk Metallic Glasses for Osteosynthesis Devices

“…The formed alloy structure was analyzed using X-ray diffraction (XRD) with Cu Kα radiation to confirm that the alloy structure was amorphous, verifying that the prepared materials are BMGs. XRD patterns and transmission electron microscope (TEM) images of Zr 65 Al 7.5 Ni 10 Cu 17.5 BMG nails, in addition to XRD patterns of Zr 65 Al 7.5 Ni 10 Cu 17.5 BMG ribbons were reported previously [ 18 , 26 ]. The XRD patterns showed that the structure of the prepared alloys were amorphous.…”

Electrochemical behavior of a Ti-based bulk metallic glass

“…It is difficult to make comparisons with the reports by Hiromoto et al on the corrosion resistance of the Zr 65 Al 7.5 Ni 10 Cu 17.5 (at.%) in Hanks' solution, Eagle's minimum essential medium (MEM), and MEM with fetal bovine serum (MEM + FBS) [49,50]. The Hanks' solution is the closest to PBS as they have the same chloride ion contents.…”