Effect of Al alloying on cavitation erosion behavior of TaSi2 nanocrystalline coatings

Authors

Jiang Xu
Shuai Kang Zhang
Xiao Lin Lu
Shuyun Jiang
Paul Munroe
Zong-Han Xie, Edith Cowan UniversityFollow

Document Type

Journal Article

Publication Title

Ultrasonics Sonochemistry

Publisher

Elsevier

School

School of Engineering

RAS ID

31228

Funders

Funding information available at: https://doi.org/10.1016/j.ultsonch.2019.104742

Comments

Xu, J., Zhang, S. K., Lu, X. L., Jiang, S., Munroe, P., & Xie, Z.-H. (2019). Effect of Al alloying on cavitation erosion behavior of TaSi2 nanocrystalline coatings. Ultrasonics Sonochemistry, 59, Article 104742. Available here

Abstract

To broaden the scope of non-aerospace applications for titanium-based alloys, both hexagonal C40 binary TaSi₂ and ternary Al alloyed TaSi₂ nanocrystalline coatings were exploited to enhance the cavitation erosion resistance of Ti-6Al-4V alloy in acidic environments. To begin with, the roles of Al addition in influencing the structural stability and mechanical properties of hexagonal C40 Ta(Si_1-xAl_x)₂ compounds were modelled using first-principles calculations. The calculated key parameters, such as Pugh's index (B/G ratio), Poisson's ratio, and Cauchy pressures, indicated that there was a threshold value for Al addition, below which the increase of Al content would render the Ta(Si_1-xAl_x)₂ compounds more ductile, but above which no obvious change would occur. Subsequently, the TaSi₂ and Ta(Si_0.875Al_0.125)₂ coatings were prepared and their microstructure and phase composition were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Both the two coatings exhibited a uniform thickness of 15 μm and a densely packed structure mainly composed of spherically shaped nanocrystallites with an average diameter of about 5 nm. Nanoindentation measurements revealed that Al alloying reduced the hardness (H) and elastic modulus (E) values of the TaSi₂ coating. Ultrasonic cavitation erosion tests were carried out by immersing coated and uncoated samples in a 0.5 M HCl solution. The cavitation-erosion analysis of the tested samples was investigated by various electrochemical techniques, mass loss weight and SEM observation. The results suggested that both coated samples provided a better protection for Ti-6Al-4V against the cavitation-erosion damage in acidic environments, but the addition of Al further improved the cavitation-erosion resistance of the TaSi₂ coating.

DOI

10.1016/j.ultsonch.2019.104742

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