ISSN: 1003-6326
CN: 43-1239/TG
CODEN: TNMCEW

Vol. 29    No. 7    July 2019

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Effect of friction stir processing on corrosion of Al-TiB2 based composite in 3.5 wt.% sodium chloride solution
Ritukesh SHARMA1, Amit Kumar SINGH2, Amit ARORA2, S. PATI1, P. S. DE1
(1. School of Minerals, Metallurgical and Materials Engineering, Indian Institute of Technology Bhubaneswar, India;
2. Materials Science and Engineering, Indian Institute of Technology Gandhinagar, India
)
Abstract: The microstructure and corrosion behavior of as-cast and friction stir processed in-situ Al-TiB2 based composite in 3.5 wt.% sodium chloride solution were investigated. The microstructure was characterized using X-ray diffractometry, scanning electron microscopy and electron backscattered diffraction technique while corrosion behavior was evaluated using linear/cyclic potentiodynamic, electrochemical impedance spectroscopy and ASTM–G67 tests. The composite contains sub-micron TiB2 particles in an aluminum matrix with both blocky and fine clusters of Al3Ti agglomerated around TiB2 and displays a low uniform corrosion rate. It is also resistant to pitting as substantiated by the absence of a positive loop in cyclic potentiodynamic tests. This is due to the non-conductive nature of TiB2 particles and a controlled amount of blocky Al3Ti phase. However, both friction stir processed and as-cast composites are susceptible to inter-granular corrosion where Al3Ti and TiB2 at grain boundaries provide initiation sites for corrosion. Electrochemical impedance study attributes this to the adverse effect of Al3Ti and TiB2 on the protective oxide surface film, which increases with immersion time.
Key words: friction stir processing; corrosion behavior; Al composite; electrochemical impedance spectroscopy (EIS)
Superintended by The China Association for Science and Technology (CAST)
Sponsored by The Nonferrous Metals Society of China (NFSOC)
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