Microstructural characterizations of magnetron sputtered Ti films on glass substrate

Ti–Al–V powder metallurgy (PM) via the hydrogenation–dehydrogenation (HDH) process

Corrosion of titanium alloys in high temperature near anaerobic seawater

Scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX) was applied to investigate the grain boundaries on ASTM grade-7 titanium (Ti-7) with a freshly polished surface, and the results showed that the alloying element, Pd, and the impurity, Fe, cosegregated to grain boundaries. Scanning electrochemical microscopy (SECM) was used to study the variations in reactivity on Ti-7 exposed to an aerated neutral solution of 0.1 M NaCl. Locations that possessed an enhanced reactivity compared to the oxide-covered (TiO2) surface of the grains on SECM images were proposed to be the boundaries. These areas were further activated by the application of a cathodic bias, and interconnection of the active locations allowed the construction of “grain boundary maps”. Variations in surface reactivity were quantitatively analyzed by fitting probe approach curves (PACs) to curves simulated with a model based on finite element analyses using the platform of COMSOL multiphysics software. The difference in reactivi...

Analyzing the Influence of Alloying Elements and Impurities on the Localized Reactivity of Titanium Grade-7 by Scanning Electrochemical Microscopy

The corrosion resistance of titanium and its alloys is a desirable property for many applications in materials science. In this report, the properties of the passive oxide film (TiO2) were examined by scanning electrochemical microscopy (SECM). A homemade closed-loop scanning electrochemical microscope was used to study these properties at the micrometer scale using ferrocenemethanol (Fc) as the redox mediator. The experimental results showed that the passive properties of a well-polished ASTM Grade-2 titanium (Ti-2) sample differed from region to region as indicated by the different current responses of the ultramicroelectrode (UME) on the SECM images. Selected spots with high feedback tip current were examined more closely by additional scanning. It was concluded that active spots with high positive feedback current were indicative of reactive structures located along crystalline grain boundaries, especially at the triple points. This observation is confirmed by comparing SECM results with optical micro...

Insights into Grain Structures and Their Reactivity on Grade-2 Ti Alloy Surfaces by Scanning Electrochemical Microscopy

For the conditions expected in a Canadian nuclear waste vault, the two corrosion processes most likely to lead to the failure of titanium waste containers are crevice corrosion and/or hydrogen induced cracking (HIC). In this report the processes likely to lead to hydrogen absorption by titanium alloys (Grades-2, -12, -16), and hence to render them susceptible to HIC are discussed. The possible paths to container failure via a combination of crevice corrosion, general passive corrosion and HIC are described and a criterion for container failure by HIC is defined. The modelling procedures developed to predict the consequences of hydrogen absorption are described, and the experimental methods used to measure required modelling parameters are discussed and the results summarized. The predictions of these models show that for alloys on which crevice corrosion either does not occur or is limited in extent (Ti-16 and Ti-12), container lifetimes of >10 a are achievable. As a result only those containers assumed to fail prematurely due to the presence of manufacturing defects need be included in assessment calculations.

D. Hardie

Papers

Hydrogen Absorption and the Lifetime Performance of Titanium Nuclear Waste Containers

Hydrogen-induced cracking of commercial purity titanium