Corrosion behaviour of as-cast ZK40 with CaO and Y additions
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Corrosion behaviour of as-cast ZK40 with CaO and Y additions. / BUZOLIN, Ricardo Henrique; MOHEDANO, Marta; MENDIS, Chamini Lakshi et al.
In: Transactions of Nonferrous Metals Society of China (English Edition), Vol. 28, No. 3, 03.2018, p. 427-439.Research output: Journal contributions › Journal articles › Research › peer-review
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TY - JOUR
T1 - Corrosion behaviour of as-cast ZK40 with CaO and Y additions
AU - BUZOLIN, Ricardo Henrique
AU - MOHEDANO, Marta
AU - MENDIS, Chamini Lakshi
AU - MINGO, Beatriz
AU - TOLNAI, Domonkos
AU - BLAWERT, Carsten
AU - KAINER, Karl Ulrich
AU - PINTO, Haroldo
AU - HORT, Norbert
PY - 2018/3
Y1 - 2018/3
N2 - The microstructures of as-cast ZK40, ZK40 with 2% (mass fraction) CaO and ZK40 with 1% (mass fraction) Y were investigated, and the intermetallic phase morphology and the distribution were characterised. By having discrete intermetallic particles at the grain boundaries for the ZK40, the microstructure was modified to a semi-continuous network of intermetallic compounds along the grain boundaries for the ZK40 with CaO or Y additions. The CaO was not found in the microstructure. However, Ca was present in Ca2Mg6Zn3 intermetallic compounds which were formed during casting. Hydrogen evolution and electrochemical impedance spectroscopy tests revealed that the addition of CaO slightly enhanced the corrosion resistance whereas Y had a negative effect on the corrosion resistance of ZK40. Immersion tests showed that severe localised corrosion as well as corrosion along the intermetallic compounds played an important role in the corrosion process of ZK40–Y whereas the localised corrosion was not pronounced for ZK40 or ZK40–CaO alloys. Micro-segregation in the α-Mg matrix was notably higher for the ZK40 alloy compared with the modified alloys. The combination of this effect with a possible formation of a more stable corrosion layer for the ZK40–CaO was attributed as the main reason for an improved corrosion resistance for the ZK40–CaO alloy.
AB - The microstructures of as-cast ZK40, ZK40 with 2% (mass fraction) CaO and ZK40 with 1% (mass fraction) Y were investigated, and the intermetallic phase morphology and the distribution were characterised. By having discrete intermetallic particles at the grain boundaries for the ZK40, the microstructure was modified to a semi-continuous network of intermetallic compounds along the grain boundaries for the ZK40 with CaO or Y additions. The CaO was not found in the microstructure. However, Ca was present in Ca2Mg6Zn3 intermetallic compounds which were formed during casting. Hydrogen evolution and electrochemical impedance spectroscopy tests revealed that the addition of CaO slightly enhanced the corrosion resistance whereas Y had a negative effect on the corrosion resistance of ZK40. Immersion tests showed that severe localised corrosion as well as corrosion along the intermetallic compounds played an important role in the corrosion process of ZK40–Y whereas the localised corrosion was not pronounced for ZK40 or ZK40–CaO alloys. Micro-segregation in the α-Mg matrix was notably higher for the ZK40 alloy compared with the modified alloys. The combination of this effect with a possible formation of a more stable corrosion layer for the ZK40–CaO was attributed as the main reason for an improved corrosion resistance for the ZK40–CaO alloy.
KW - CaO addition
KW - corrosion behaviour
KW - Mg alloy
KW - Y addition
KW - ZK40
KW - Engineering
UR - http://www.scopus.com/inward/record.url?scp=85045108738&partnerID=8YFLogxK
U2 - 10.1016/S1003-6326(18)64676-X
DO - 10.1016/S1003-6326(18)64676-X
M3 - Journal articles
AN - SCOPUS:85045108738
VL - 28
SP - 427
EP - 439
JO - Transactions of Nonferrous Metals Society of China
JF - Transactions of Nonferrous Metals Society of China
SN - 1003-6326
IS - 3
ER -