Effects of Yttrium on the Microstructure and Corrosion Behavior of Pb-39Mg-10Al-1B-Y Alloys
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JMEPEG https://doi.org/10.1007/s11665-020-05317-4
Effects of Yttrium on the Microstructure and Corrosion Behavior of Pb-39Mg-10Al-1B-Y Alloys Zhiqi Feng, Weizong Bao, Longke Bao, Mingjun Peng, and Yonghua Duan Submitted: 13 May 2020 / Revised: 30 September 2020 / Accepted: 31 October 2020 Pb-39Mg-10Al-1B-Y alloys with Y = 0, 0.2, 0.4, 0.6, 0.8, and 1.0 (wt.%) were fabricated by melting and casting. The microstructure and electrochemical corrosion behavior of the Pb-39Mg-10Al-1B-Y alloys in a 3.5 wt.% NaCl solution were investigated using x-ray diffraction, electron probe microanalysis, and scanning electron microscopy, polarization curve tests, electrochemical impedance spectroscopy (EIS), and electrochemical noise (EN). Mg2Pb + Pb eutectic gains are refined, and the distribution of Mg17Al12 + Mg eutectic gains becomes continuous by with the addition of Y. The polarization curves, EIS results and EN results show that the corrosion resistance of the alloys with various Y concentrations is in the order 0.8 > 1 > 0.6 > 0.4 > 0.2 > 0. The primary corrosion behaviors of Pb-39Mg-10Al-1B-Y alloys when Y £ 0.4 wt.% and Y > 0.4 wt.% are general corrosion and localized corrosion, respectively. There is a Mg-Mg2Pb galvanic cell present with Mg2Pb as the cathode and Mg as the anode. Moreover, Cl2 can accelerate the corrosion of the Mg phase. Keywords
corrosion resistance, EIS, Pb-39Mg-10Al-1B-Y alloy
EN,
microstructure,
1. Introduction Recently, Pb and its alloys have received considerable attention owing to the low cost, large linear attenuation coefficient, and excellent electromagnetic shielding performance (Ref 1–4). Boron has excellent suppression and capture of radiation as well as neutron shielding characteristics (Ref 5). Magnesium alloys, owing to their electrochemical performance, have also attracted widespread attention (Ref 6–8). Therefore, Pb-Mg-B alloys have been prepared to integrate the advantages of Pb, Mg, and B, and numerous experiments have also verified that these alloys have excellent shielding properties; however, their mechanical properties are generally poor (Ref 9–11). To improve the mechanical properties, a new alloy, Pb-39Mg10Al-1B, was used as a nuclear shielding system (Ref 12), and this alloy had good mechanical properties, with a Brinell hardness of 160 HBS and a tensile strength of 105 MPa (Ref 13, 14). In general, shielding materials that capture rays and neutron shields can operate for extended periods of time under the complex corrosion conditions of neutral salt solutions. However, their sensitivity to corrosion limits their service life, which hinders their feasibility in high corrosion seawater environments. Therefore, methods that improve their corrosion resistance should be fully considered. From a metallurgical perspective, during the alloy melting process, rare earth elements will quickly combine with impurities (Fe, Ni, Cu, Zhiqi Feng, Weizong Bao, Longke Bao, Mingjun Peng, and Yonghua Duan, Faculty of Material Science and Engineering, Kunming University of Science and Technology,
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