The corrosion and passivity of sputtered Mg–Ti alloys

Abstract

This study explored the possibility of forming a "stainless" Mg-Ti alloy. The electrochemical behavior of magnetron-sputtered Mg-Ti alloys was measured in a NaCl solution, and the surface films on the alloys were examined by XPS, SEM and TEM. Increased corrosion resistance was observed with increased Ti content in the sputtered Mg-Ti alloys, but passive-like behavior was not reached until the Ti level (atomic %) was higher than the Mg level. The surface film that formed on sputtered Mg-Ti based alloys in NaCl solution was thick, discontinuous and nonprotective, whereas a thin, continuous and protective Mg and Ti oxide film was formed on a sputtered Ti-Mg based alloy.

The Corrosion Behavior of Mg5Y in Nominally Distilled Water

“…Consequently, a hollow ‘bump’ would be obtained on a corroded surface. This kind of corrosion product deposition has been experimentally confirmed in another study under TEM using the FIB technique . A corrosion product ‘bump’ or ‘volcano’ was a result of ion migration.…”

Corrosion and passivation of magnesium alloys

“…Recently, the threshold level of Ti to passivate Mg was measured by Song et al [40]. The corrosion potential of the magnetron sputtered Mg-Ti alloy increased with increasing Ti content (see Table 1 and Fig.…”

“…Thus, there may be a possibility to obtain a corrosion resistant Mg alloy through alloying with passivating elements, such as Cr, Ti, Al, Ni, Zr, etc. [40,77]. Alloying can modify the matrix phase composition, and change the amounts and distribution of the second and other phases in an alloy.…”

“…However, the solid solubility of the strong passivating elements is low in Mg matrix. For example, the solid solubility of Ni in Mg is only a few ppm, and Cr and Ti cannot be dissolved in Mg under equilibrium conditions [40]. These elements that are difficult to alloy with Mg can be produced dissolved in Mg through non-equilibrium sputter deposition.…”

“…Inspired by the high corrosion resistance of stainless steels in corrosive environments, and the suggestion of Song and Atrens [3], researchers have explored the development of a Mg alloy [15,22,39,40] much more resistant than all current Mg alloys. Song and Atrens [3] indicated that a "stainless" Mg alloy much more corrosion resistant than any current Mg alloy could be developed if an alloying element could produce a passive film on Mg.…”