Microgalvanic Corrosion of Mg-Ca and Mg-Al-Ca Alloys in NaCl and Na2SO4 Solutions.

Peixu Yang,Shaojun Zhang,Weineng Tang,Guonan Liu,Sensen Huang,Songbo Ye,Weidong Zhang,Baojing Feng,Shijie Zhu,Jinhui Liu

doi:10.3390/ma14237140

Abstract

As a kind of potential biomedical material, Mg–Ca alloy has attracted much attention. However, the role of Ca-containing intermetallics in microgalvanic corrosion is still controversial. In 0.6 mol/L NaCl and Na2SO4 solutions, the microgalvanic corrosion behavior of the second phase and Mg matrix of Mg–Ca and Mg–Al–Ca alloys was examined. It was confirmed that the Mg2Ca phase acts as a microanode in microgalvanic corrosion in both NaCl and Na2SO4 solutions, with the Mg matrix acting as the cathode and the Al2Ca phase acting as the microcathode to accelerate corrosion of the adjacent Mg matrix. It was also found that Cl− and SO42− have different sensibilities to microgalvanic corrosion.

Highlights

Magnesium alloys have attracted special interest in many fields for their light weight, high specific strength, and great biodegradability [1,2]
The number of second phases at the grain boundaries increased, and the second phase morphology changed from a semicontinuous network in Mg–Ca alloys to a continuous network in Mg–Al–Ca alloys
The second phase in the Mg–Ca alloy was the Mg2Ca phase, and the types of second phase in Mg–Al–Ca alloys were determined by the mass ratio of Ca/Al [32]

Summary

Introduction

Magnesium alloys have attracted special interest in many fields for their light weight, high specific strength, and great biodegradability [1,2]. They have considerable potential for application in transportation, aerospace, electronic technology, and especially biomedicine [3,4,5]. It is regrettable that rare earth elements are harmful to the human body and not suitable as human implant materials. Zhu et al reported a new Mg–Al–Ca alloy in which a majority of deformable Al2Ca precipitates were formed. This alloy demonstrated one of the highest combinations of tensile elongation and work hardening capacity among existing Mg alloys [22]

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Results

Conclusion