Corrosion onset associated with the reinforcement and secondary phases in B4C-6061Al neutron absorber material in H3BO3 solution

• Published in: Corrosion science 2019-06, Vol.153, p.74-84
• Main Authors: Zhou, Y.T., Zan, Y.N., Wei, X.X., Yang, B., Zhang, B., Zheng, S.J., Shao, X.H., Dong, J.H., Ma, X.L., Xiao, B.L., Wang, Q.Z., Ma, Z.Y.
• Format: Article
• Language: English
• Subjects: A. Aluminium; A. Metal matrix composites; Absorbers (materials); Aluminum base alloys; B. TEM; Boron carbide; C. Interfaces; C. Pitting corrosion; Corrosion; Corrosion resistance; Corrosion resistant alloys; High temperature; Magnesium compounds; Metal silicides; Neutron absorbers; Pitting (corrosion); Reaction products
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2019.03.042

•The microstructures in B4C-6061Al composites hot-pressed at different temperatures were studied.•The corrosion behavior of the composite in H3BO3 and Cl−-containing H3BO3 solutions were examined.•Quasi in-situ TEM was performed to reveal the pitting initiations.•Corrosion in the composite are mainly associated with B4C/Al interface and MgB2 dispersions.•Dealloying of Mg2Si does not obviously deteriorate the corrosion resistance of the composite. The microstructures in B4C-6061Al composite hot-pressed at different temperatures (560 °C, 620 °C) are characterized, and the corrosion behavior of the materials is studied using electrochemical tests and quasi in-situ TEM observations. The composite fabricated at 620 °C is composed of more matrix-reinforcement reaction products (Al3BC at the interfaces and MgB2 in the alloy matrix). Corrosion occurred slightly in boric acid but severely in Cl−-containing solution. The B4C/Al interface in both samples is preferentially attacked and the MgB2 dispersions in the high-temperature-pressed composite remarkably promoted the pitting. Dealloying of Mg2Si precipitate does not obviously deteriorate the corrosion resistance of the composite.