Effect of Microstructure on the Corrosion Behavior of as-cast and Extruded Mg–Sn–Y Alloys

Abstract

The effect of microstructure on the corrosion behavior of as-cast and extruded Mg-Sn-Y alloys was investigated using measurements of hydrogen evolution, weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy, and scanning Kelvin probe force microscopy. The results showed that the corrosion rate increased in the following order: as-cast, transversal section of bar, and longitudinal section of bar. The higher corrosion rate was related to the refinement of grain size, the micro-galvanic corrosion between second phases and α-Mg matrix, and the micro-galvanic corrosion between different orientated grains. The Volta potentials of Sn 3 Y 5 and MgSnY phases were more positive than that of the α-Mg matrix. Accordingly, the Sn 3 Y 5 and MgSnY phases acted as the cathodes for micro-galvanic corrosion and accelerated the corrosion of α-Mg matrix. After extrusion, the content of second phases reduced and the grain size significantly refined. As a consequence, extrusion increased the corrosion rate of Mg-Sn-Y alloys, as the contribution of grain size refinement to increase the corrosion rate was much bigger than that of the content decrease of second phases to decrease the corrosion rate.

Effects of Texture and Discharge Products on the Discharge Performance of Mg Anodes for Mg Air Batteries

“…4e, the grains in red color represent the basal orientated grains, whereas the grains in blue and green colors represent the prismatic orientated grains. 26,[32][33][34] The texture characteristics of the four anodes are different. The ET0°anode has a traditional strong basal texture, which is consistent with the commonly reported in extruded AZ31 sheet.…”

Modified Microstructures and Corrosion Behaviors of Mg-Gd-Cu Alloys through Annealing Treatment

“…Corrosion behaviors.-The primary anodic and cathodic reaction of Mg alloys corrosion are shown in formula (5) and formula (6), respectively, 56 and hydrogen evolution reaction (HER) is believed as the main reaction. [56][57][58] In previous studies, the evolved hydrogen during immersion tests has been collected in order to calculate the corrosion rate P AH and the discrepancy between the P AH and the P W was observed. 34,41,57,59 The dissolution of hydrogen in solution was considered to be the primary reason.…”

“…[56][57][58] In previous studies, the evolved hydrogen during immersion tests has been collected in order to calculate the corrosion rate P AH and the discrepancy between the P AH and the P W was observed. 34,41,57,59 The dissolution of hydrogen in solution was considered to be the primary reason. 33 On the other hand, it was shown that oxygen reduction reaction (ORR, shown in formula ( 7)) contributed to the cathodic process as well.…”

Discharge properties of Mg-Sn-Y alloys as anodes for Mg-air batteries

“…The average grain sizes of the Mg-0.2Sn-1.4Y, Mg-0.4Sn-1.4Y, and Mg-0.7Sn-1.4Y alloys were 4.3, 4.1, and 3.8 µm, respectively. The grain refinement was attributed to the second phase particle induced nucleation mechanism, namely the particle-stimulated nucleation (PSN) mechanism [28,[60][61]. The strong PSN mechanism because of a high content (vol%) of second phase particles gives rise to the drastic grain refinement [60].…”