Effect of Iron Content on Corrosion Properties of Pure Titanium as Grain Refiner.

Kwangsuk Park,Hyung-Ki Park,Ki-Beom Park,Bosung Seo,Hyeon-Tae Im

doi:10.3390/ma14237193

Kwangsuk Park, Hyung-Ki Park + Show 3 more

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https://doi.org/10.3390/ma14237193

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Abstract

Microstructures and corrosion properties of pure titanium were characterized when iron was used as a grain refiner. The added Fe element acted as a strong grain refiner for pure titanium by forming β Ti phase at grain boundaries, and 0.15 wt% Fe was revealed to be a sufficient amount to make the grain size of pure titanium below 20 μm, which was the requirement for the desired titanium cathode. However, corrosion resistance was decreased with the Fe amount added. From the open circuit potential (OCP) results, it was obvious that the TiO2 stability against the reducing acid environment was deteriorated with the Fe amount, which seemed to be the main reason for the decreased corrosion resistance. Electrochemical impedance spectroscopy (EIS) results showed that both the decrease in the compact oxide film’s resistance (Rb) and the appearance of the outer porous film occurred as a result of the dissolution of the TiO2 layer, whose phenomena became more apparent as more Fe was added.

Highlights

IntroductionIron Content on Corrosion PropertiesTitanium and titanium alloys have been used in corrosive environments, such as seawater and hazardous gases, due to their excellent corrosion resistance [1,2,3,4]
Iron Content on Corrosion PropertiesTitanium and titanium alloys have been used in corrosive environments, such as seawater and hazardous gases, due to their excellent corrosion resistance [1,2,3,4]
As a β stabilizing element, a β Ti phase became dominant at high temperature over 590 ◦ C with the Fe content, and only a TiFe phase formed below 590 ◦ C, indicating that this amount of Fe was not enough to form and/or stabilize β Ti phase at room temperature

Summary

Introduction

Iron Content on Corrosion PropertiesTitanium and titanium alloys have been used in corrosive environments, such as seawater and hazardous gases, due to their excellent corrosion resistance [1,2,3,4]. The increased grain boundary as a result of small grain size could provide enough of a pathway to enable evolved hydrogen on a titanium drum during electrodeposition of Cu to diffuse into a titanium matrix. Iron exists in pure titanium as an impurity, and its content is usually limited to 0.3 wt%, as it could affect microstructure in terms of β phase stabilization and/or Tix Fe intermetallic formation [10]. These microstructural changes induced by the addition of Fe would be of use in refining grain size.

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