| Summary: | This paper analyzed the effect of long period stacking ordered phases (LPSO) and aged-precipitations on corrosion behavior of Mg–6Gd–2Y–1Zn–0.3Zr magnesium alloys. As-forged alloys were subjected to aging at 225 °C for a period of 4 and 12 h such as to acquire the required microstructure. For these as-forged Mg alloys, some structures of LPSO phases were broken and replaced by fine dynamic recrystallized grains. After undergoing the aging treatment for a 4 h period, these alloys demonstrated a higher number of recrystallized grains and lesser LPSO phases. However, the 12 aging of the alloys produced the least number of LPSO phases, but produced a considerable amount of aged-precipitations on the recrystallized grains. During the period of 120 h immersion in 0.1 mol NaCl solution, the corrosion behavior of the alloys was mainly determined by the decreased volume fraction of LPSO phases and the increased volume fraction of aged-precipitations. Alloys after aging for a 12 h period, displayed the most critical corrosion rate owing to the severe micro-galvanic corrosion between high voltage aged-precipitations or LPSO phases and Mg-matrix, whereas, the alloys after aging for a 4 h period, displayed the best corrosion resistance due to the lesser volume fraction of LPSO phases. As-forged alloys with the most amount of volume fraction of LPSO phases displayed a moderate corrosion resistance.
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