Influence of Ca-addition amount on corrosion behavior of Ca-added Mg alloys

Yuta Shimada, Mika Tsunakawa, Kae Nakamura, Takahiro Ishizaki

Research output: Contribution to conferencePaperpeer-review

Abstract

In recent years, Ca-added Mg alloys has been developed to improve the flame-resistance. Thus Ca-added Mg alloys is expected to be used as the component materials for transport industry and electronic devices because of their safety and lightweight. However, it has been revealed that the corrosion resistance was lowered if Ca was added to Mg alloys. In this study, we aimed to investigate the corrosion behavior of Ca-added Mg alloys in NaCl aqueous solution. FE-SEM and XRD measurements demonstrated that Al-Mn compound and MnAl2O4 were precipitated in AZ61 (0 wt% Ca) and Al2Ca phase was present in AZCa611 (1 wt% Ca) and AZCa612 (2 wt% Ca). And the existence amount of Al2Ca phase in the Ca-added Mg alloys increased with an increase in Ca-addition amount in the AZ61 Mg alloy substrate. It is known that Mg17Al12 (β phase) is present in AZ61, AZCa611, AZCa612. KFM measurements revealed that the surface potential difference between Al2Ca and α-Mg was larger than that between Al-Mg compound, MnAl2O4, or Mg17Al12 (β phase) and α-Mg. The topographic images of the samples after the immersion tests in NaCl aqueous solution demonstrated that Mg(OH)2 was deposited on each precipitate. Therefore, each precipitate acts as a cathode site of local cells. Thus Al2Ca could be one of the causes lowering the corrosion resistance of Ca-added magnesium alloys.

Original languageEnglish
Publication statusPublished - 2017 Jan 1
EventJoint European Corrosion Congress 2017, EUROCORR 2017 and 20th International Corrosion Congress and Process Safety Congress 2017 - Prague, Czech Republic
Duration: 2017 Sep 32017 Sep 7

Other

OtherJoint European Corrosion Congress 2017, EUROCORR 2017 and 20th International Corrosion Congress and Process Safety Congress 2017
CountryCzech Republic
CityPrague
Period17/9/317/9/7

Keywords

  • Ca-added Mg alloys
  • Local cells
  • Surface potential

ASJC Scopus subject areas

  • Colloid and Surface Chemistry
  • Surfaces and Interfaces

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