Electrochemical Corrosion Behavior of Powder Metallurgy Ti6Al4V Alloy

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JMEPEG https://doi.org/10.1007/s11665-020-05324-5

Electrochemical Corrosion Behavior of Powder Metallurgy Ti6Al4V Alloy Yang Zhou, Fang Yang, Yanru Shao, Boxin Lu, Tianxing Lu, and Zhimeng Guo Submitted: 25 March 2020 / Revised: 12 October 2020 / Accepted: 1 November 2020 The corrosion behavior of powder metallurgy (PM) Ti6Al4V alloys with different relative densities ranged from 95.2 to 99.5% is investigated in 3.5 wt.% NaCl solution at room temperature by electrochemical methods, including potentiodynamic polarization curves and electrochemical impedance spectroscopy. For comparison, traditional wrought Ti6Al4V alloy with full densification is also investigated. The results show that the corrosion resistance of PM Ti6Al4V alloys increases with the increasing density. All the studied samples exhibit low Ip values (in the order of 1026 A cm22), indicating good corrosion resistance under current experimental conditions. Therefore, density effect on the corrosion resistance of PM Ti6Al4V alloys is less significant. It is worth noting that the corrosion resistance and mechanical performance of PM Ti6Al4V alloys with nearly full densification are comparable to those of wrought alloys. Therefore, PM Ti alloys are promising candidates in the marine application. Keywords

corrosion behavior, density, mechanical performance, powder metallurgy, Ti6Al4V alloy

1. Introduction Titanium (Ti) alloys are emerging as considerable metallic material for advanced applications due to their excellent combination of specific mechanical properties, corrosion resistance and biocompatibility. Exceptions are limited to highly demanding sectors such as aeronautical, military and biomedical (Ref 1, 2). High production cost is the main reason that hinders Ti alloys as a selection in the design of engineering components for most industrial applications, which is associated with strictly controlled production steps due to its high affinity to interstitials (i.e., oxygen and nitrogen) and poor machinability related to its low thermal conductivity. Compared with traditional ingot metallurgy (IM) technology, powder metallurgy (PM) technology has many advantages, such as near-net-shape formability, uniform microstructure and isotropic properties (Ref 3). PM has therefore been considered as a promising method for preparing low-cost and high-performance Ti alloys. Many related studies have been conducted to prepare PM Ti alloys (Ref 4-6). However, two inevitable issues with PM Ti alloys are the existence of pores and powder particle boundary, where the Yang Zhou, Yanru Shao, Boxin Lu, and Tianxing Lu, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China; and Fang Yang and Zhimeng Guo, Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China; Innovation Group of Marine Engineering Materials and Corrosion Control, Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519080, China; and Guangzhou Institute of Advanced Mat

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