Effect of multiaxial deformation on structure, mechanical properties, and corrosion resistance of a Mg-Ca alloy

• Published in: Journal of magnesium and alloys 2022-01, Vol.10 (1), p.266-280
• Main Authors: Yurchenko, N.Yu, Stepanov, N.D., Salishchev, G.A., Serebryany, V.N., Martynenko, N.S., Lukyanova, E.A., Rokhlin, L.L., Birbilis, N., Dobatkin, S.V., Estrin, Y.Z.
• Format: Article
• Language: English
• Subjects: Corrosion; Mechanical properties; Metals and alloys; Microstructure; Multiaxial deformation; Recrystallization
• ISSN: 2213-9567; 2213-9567
• DOI: 10.1016/j.jma.2021.07.004

This article provides a report on the effect of multiaxial deformation (MAD) on the structure, texture, mechanical characteristics, and corrosion resistance of the Mg-0.8 (wt.)% Ca alloy. MAD was carried out on the alloy in the as-cast and the annealed states in multiple passes, with a stepwise decrease in the deformation temperature from 450 to 250 °C in 50 °C steps. The cumulative true strain at the end of the process was 22.5. In the case of the as-cast alloy, this resulted in a refined microstructure characterized by an average grain size of 2.7 µm and a fraction of high-angle boundaries (HABs) of 57.6%. The corresponding values for the annealed alloy were 2.1 µm and 68.2%. The predominant mechanism of structure formation was associated with discontinuous and continuous dynamic recrystallization acting in concert. MAD was also shown to lead to the formation of a rather sharp prismatic texture in the as-cast alloy, whilst in the case of the annealed one the texture was weakened. A displacement of the basal poles {00.4} from the periphery to the center of a pole figure was observed. These changes in the microstructure and texture gave rise to a significant improvement of the mechanical characteristics of the alloy. This included an increase of the ultimate tensile strength reaching 308 MPa for annealed material and 264 MPa for the as-cast one in conjunction with a twofold increase in ductility. A further important result of the MAD processing was a reduction of the rate of electrochemical corrosion, as indicated by a significant decrease in the corrosion current density in both microstructural states of the alloy studied.