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The structure, magnetism, magnetic compensation behavior, exchange interaction, and electronic structures of Co50-xMn25Ga25+x and Co50-xMn25+xGa25 (x = 0–25) alloys have been systematically investigated by both experiments and first-principles calculations. We found that all the samples exhibited body centered cubic structures with high degree of atomic ordering. With increasing Ga content, the composition dependence of lattice parameter shows a kink point at the middle composition in Co50-xMn25Ga25+x alloys, which can be attributed to the enhanced covalent hybridization between the main-group Ga and the transition-metal atoms. Moreover, a complicated magnetic competition has been revealed in Co50-xMn25Ga25+x alloys, which causes the Curie temperature dramatically decrease and results in a magnetic moment compensation behavior. In Co50-xMn25+xGa25 alloys, however, with increasing Mn content, an additional ferrimagnetic configuration is established in the native ferromagnetic matrix, which causes the molecular moment monotonously decrease and the exchange interaction enhance gradually. The electronic structure calculations indicate that the Co50-xMn25+xGa25 alloys are likely to be in a coexistence state of the itinerant and localized magnetism. Our study will be helpful to understand the nature of magnetic ordering as well as to tune magnetic compensation and electronic properties of Heusler alloys.

A self‐designed experiment circuit was adopted to investigate the effect of alternating current (AC) on corrosion rate and cathodic protection (CP) potential of cathodically protected Q235 steel in the simulated soil solution of 4 g/L sodium sulfate. It is found that the corrosion induced by AC current can be controlled by increasing CP current when AC current density is below 300 A/m2. However, in case that CP current is too large the corrosion of Q235 steel will be accelerated. Moreover, CP potential of Q235 steel shifts considerably due to AC current and the shift direction depends on the applied CP current. Based on the experimental results, a combination role of CP current and AC current considering micro‐electrons transfer is introduced to explore the mechanism of AC corrosion.

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