TY - JOUR
T1 - Surface morphology of a die-cast Mg alloy
AU - Unigovski, Ya B.
AU - Gutman, E. M.
N1 - Funding Information:
The present work was sponsored by the Consortium of Magnesium Technologies Development (the Ministry of Industry of Israel). We would like to thank N. Frumin and O. Nabutovski (Ben-Gurion University of the Negev) for kind assistance in AES and SEM. We thank Z. Koren and H. Rosenson (Israel Institute of Metals, Technion, Haifa) for supplying us with die-cast specimens.
PY - 1999/1/1
Y1 - 1999/1/1
N2 - We have studied the microstructure, phase composition and morphology of the intermetallic β-phase in the layer surface of the most widespread magnesium alloy AZ91D (Mg-9 wt.% Al-1 wt.% Zn) used in pressure die casting. Auger electron spectroscopy (AES), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and optical microscopy have been applied. The surface of the AZ91D Mg alloy consists of an oxide-metallic film with a thickness of about 0.15 micron containing Mg and Al oxides. Prolonged aging in air at 200 °C promotes an increase in the MgO/Al2O3 ratio from 9±2 to 14±2. The aluminum concentration gradient in the surface layer is rather significant. The external layer of as-cast specimens contains up to 32 at.% Al, whereas α-Mg grains in the bulk contain, on the average, about 5 at.% Al. Aging leads to a substantial increase in the surface concentration of aluminum at the expense of the acceleration of its diffusion and the intensification of supersaturated solid solution decomposition. During creep tests at elevated temperatures the morphology of the β-phase is significantly affected by strain and, to a lesser extent, by the casting temperature.
AB - We have studied the microstructure, phase composition and morphology of the intermetallic β-phase in the layer surface of the most widespread magnesium alloy AZ91D (Mg-9 wt.% Al-1 wt.% Zn) used in pressure die casting. Auger electron spectroscopy (AES), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and optical microscopy have been applied. The surface of the AZ91D Mg alloy consists of an oxide-metallic film with a thickness of about 0.15 micron containing Mg and Al oxides. Prolonged aging in air at 200 °C promotes an increase in the MgO/Al2O3 ratio from 9±2 to 14±2. The aluminum concentration gradient in the surface layer is rather significant. The external layer of as-cast specimens contains up to 32 at.% Al, whereas α-Mg grains in the bulk contain, on the average, about 5 at.% Al. Aging leads to a substantial increase in the surface concentration of aluminum at the expense of the acceleration of its diffusion and the intensification of supersaturated solid solution decomposition. During creep tests at elevated temperatures the morphology of the β-phase is significantly affected by strain and, to a lesser extent, by the casting temperature.
UR - http://www.scopus.com/inward/record.url?scp=0033353620&partnerID=8YFLogxK
U2 - 10.1016/S0169-4332(99)00337-2
DO - 10.1016/S0169-4332(99)00337-2
M3 - Article
AN - SCOPUS:0033353620
SN - 0169-4332
VL - 153
SP - 47
EP - 52
JO - Applied Surface Science
JF - Applied Surface Science
IS - 1
ER -