Thixomolded AZ91D and MRI153M magnesium alloys and their enhanced corrosion resistance

Publikation: Beiträge in ZeitschriftenZeitschriftenaufsätzeForschungbegutachtet

Authors

  • Ricardo H. Buzolin
  • Polina Volovitch
  • Alina Maltseva
  • Sviatlana Lamaka
  • Carsten Blawert
  • Chamini L. Mendis
  • Andreas Lohmüller
  • Karl U. Kainer
  • Norbert Hort

AZ91D and MRI153M alloys were produced by thixomolding. Their corrosion resistance is significantly higher than that of similar materials produced by ingot or die-casting. A corrosion rate smaller than 0.2 mm/year in 5 wt% NaCl solution is measured for the thixomolded AZ91D alloy. The corrosion behaviour was evaluated using immersion tests, electrochemical impedance spectroscopy, hydrogen evolution, glow discharge optical emission spectroscopy, and atomic emission spectroelectrochemistry. A bimodal microstructure is observed for both alloys, with the presence of coarse primary α-Mg grains, fine secondary α-Mg grains, β-phase, and other phases with a minor volume fraction. The amount of coarse primary α-Mg is significantly higher for the AZ91D compared with the MRI153M. The network of β-phase around the fine secondary α-Mg grains is better established in the thixomolded AZ91D alloy. A combination of several factors such as the ratio of primary to secondary α-Mg grains, localised corrosion or barrier effect due to other phases, as well as regions of preferential dissolution of the α-Mg due to chemical segregation, are thought to be responsible for the high corrosion resistance exhibited by the thixomolded AZ91D and MRI153M.

OriginalspracheEnglisch
ZeitschriftMaterials and Corrosion
Jahrgang71
Ausgabenummer3
Seiten (von - bis)339-351
Anzahl der Seiten13
ISSN0947-5117
DOIs
PublikationsstatusErschienen - 01.03.2020
Extern publiziertJa

DOI