Optimization of Strength, Ductility and Corrosion Resistance in Ti-Mo Base Alloys by Controlling Mo Equivalency and Bond Order

Abstract

The crevice corrosion resistance in high chloride and high acidic solution at high temperature in Ti-15Mo-5Zr and Ti-15Mo-5Zr-1Fe alloys and the tensile properties at ambient temperature in Ti-15Mo-5Zr-1Fe alloy were investigated in this study. The crevice corrosion resistance in Ti-15Mo-5Zr alloy with a Mo equivalency of 18.2 mass%, which was previously reported to show a combination of the high yield strength and the significant uniform elongation, was almost twice as high as that in Ti-15Mo alloy when the bond order (Bo) increased from 2.8126 to 2.8232. A linear correlation between the crevice corrosion resistance and the Bo was confirmed in the Ti-Mo base alloys with the Bo between 2.7900 and 2.8232. Although the high crevice corrosion resistance, Ti-15Mo-5Zr-1Fe alloy with a Mo equivalency of 21.2 mass% showed high yield strength but negligible uniform elongation due to the deformation by dislocation slip. This study suggested that the two parameters of the Mo equivalency and the Bo are useful for an optimization of strength, ductility and corrosion resistance in Ti-Mo base alloys.

Enthalpies of Solution in Ti–X (X = Mo, Nb, V and W) Alloys from First-Principles Calculations

“…Although the Mo equivalency is an arbitrary parameter, Ti alloys can be arranged in a sequence in accordance with the stability of the ¢-phase by using the Mo equivalency, which is very useful and convenient for researchers developing new Ti-based alloys. 49,52) Thus, the critical concentration is of significant scientific and engineering value as a basis for determining Mo equivalency.…”

Design of Ti-Mo-W Alloys and Its Correlation with Corrosion Resistance in Simulated Body Fluid (SBF)

“…The addition of a sufficient amount of Molybdenum gives Titanium a very good resistance to corrosion [ 31 , 34 ]. In several studies [ 2 , 16 , 35 , 36 ], it is observed that a minimum percentage of 15 wt% Mo can lead to an increase in corrosion resistance in biological environments at high temperatures for titanium alloys [ 8 , 31 , 36 ].…”

Obtaining and Characterization of the Ti15Mo5W Alloy for Biomedical Applications

“…But the use of this material does not solve several problems [3][4][5][6][7] Starting with the results obtained by several researchers [8] a theoretical method for alloy design has been developed without any trial-and-error experiments. The design strategy has been developed by combined some parameters as: the bond order (Bo); the metal -orbital energy level (Md); the electron/atom (e/a) ratio, and the Mo equivalency [9,10].…”