Role of Ca on the corrosion resistance of Mg–9Al and Mg–9Al–0.5Mn alloys
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In: Journal of Alloys and Compounds, Vol. 811, 151992, 30.11.2019.
Research output: Journal contributions › Journal articles › Research › peer-review
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TY - JOUR
T1 - Role of Ca on the corrosion resistance of Mg–9Al and Mg–9Al–0.5Mn alloys
AU - Mingo, Beatritz
AU - Mohedano, M.
AU - Blawert, C.
AU - del Olmo, R.
AU - Hort, Norbert
AU - Arrabal, R.
PY - 2019/11/30
Y1 - 2019/11/30
N2 - The effect of Ca additions on the microstructure and corrosion resistance of Mg–9Al and Mg–9Al-0.5Mn alloys is investigated. Model alloys were used instead of a commercial AZ91 alloy in order to avoid masking effects from other alloying elements. Grain size and secondary phases were characterised with special interest in their Volta potential. Corrosion performance was evaluated by hydrogen evolution and electrochemical methods. A synergetic effect was found when Ca and Mn were added in small amounts (0.5 wt%), reaching corrosion rates up to two orders of magnitude lower than the model Mg–9Al alloy. Such improvement was associated with Ca decreasing the Volta potential of the β-phase and with Ca and Mn decreasing the galvanic activity of Fe-rich intermetallics. Precipitation of Al2Ca decreased the amount of β-phase and had a negative impact on the corrosion resistance due to its cathodic behaviour.
AB - The effect of Ca additions on the microstructure and corrosion resistance of Mg–9Al and Mg–9Al-0.5Mn alloys is investigated. Model alloys were used instead of a commercial AZ91 alloy in order to avoid masking effects from other alloying elements. Grain size and secondary phases were characterised with special interest in their Volta potential. Corrosion performance was evaluated by hydrogen evolution and electrochemical methods. A synergetic effect was found when Ca and Mn were added in small amounts (0.5 wt%), reaching corrosion rates up to two orders of magnitude lower than the model Mg–9Al alloy. Such improvement was associated with Ca decreasing the Volta potential of the β-phase and with Ca and Mn decreasing the galvanic activity of Fe-rich intermetallics. Precipitation of Al2Ca decreased the amount of β-phase and had a negative impact on the corrosion resistance due to its cathodic behaviour.
KW - Alloying
KW - Calcium
KW - Corrosion
KW - Magnesium
KW - Manganese
KW - Volta potential
KW - Engineering
UR - http://www.scopus.com/inward/record.url?scp=85071388560&partnerID=8YFLogxK
UR - https://www.mendeley.com/catalogue/48f451a0-61ea-388b-9379-10ef3b4ea5f0/
U2 - 10.1016/j.jallcom.2019.151992
DO - 10.1016/j.jallcom.2019.151992
M3 - Journal articles
AN - SCOPUS:85071388560
VL - 811
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
SN - 0925-8388
M1 - 151992
ER -