TY - JOUR
T1 - Roles of impurities on precipitation kinetics of dilute Al-Sc alloys
AU - Beeri, Ofer
AU - Dunand, David C.
AU - Seidman, David N.
PY - 2010/6
Y1 - 2010/6
N2 - High-purity (HP) aluminum and commercial purity (CP) aluminum (major impurities: ∼250at.ppm Si and ∼130at.ppm Fe) are alloyed with ∼250 to ∼1100at.ppm Sc and ∼50at.ppm RE (RE=La, Ce, Pr, or Nd). The alloys are homogenized at 640°C and aged at 300°C. The precipitation kinetics, basic mechanical properties, and microstructure are studied using AC electrical conductivity, microhardness measurements, scanning electron microscopy in conjunction with energy dispersive X-ray spectroscopy, and atom-probe tomography, respectively. The Fe and RE elements form micrometer-scale diameter Al∼3(Fe,RE) primary precipitates, which have no effect on the mechanical properties. Silicon accelerates the precipitation kinetics of nanometer-scale diameter Al3Sc precipitates, increasing their number density, thereby resulting in higher microhardness values for CP aluminum than the HP aluminum having the same Sc concentration. Additionally, the Sc equilibrium solubility in the α-Al matrix is estimated and Orowan's strengthening mechanism is confirmed for the Al3Sc precipitates.
AB - High-purity (HP) aluminum and commercial purity (CP) aluminum (major impurities: ∼250at.ppm Si and ∼130at.ppm Fe) are alloyed with ∼250 to ∼1100at.ppm Sc and ∼50at.ppm RE (RE=La, Ce, Pr, or Nd). The alloys are homogenized at 640°C and aged at 300°C. The precipitation kinetics, basic mechanical properties, and microstructure are studied using AC electrical conductivity, microhardness measurements, scanning electron microscopy in conjunction with energy dispersive X-ray spectroscopy, and atom-probe tomography, respectively. The Fe and RE elements form micrometer-scale diameter Al∼3(Fe,RE) primary precipitates, which have no effect on the mechanical properties. Silicon accelerates the precipitation kinetics of nanometer-scale diameter Al3Sc precipitates, increasing their number density, thereby resulting in higher microhardness values for CP aluminum than the HP aluminum having the same Sc concentration. Additionally, the Sc equilibrium solubility in the α-Al matrix is estimated and Orowan's strengthening mechanism is confirmed for the Al3Sc precipitates.
KW - Atom probe
KW - Dilute aluminum alloys
KW - Impurities
KW - Precipitation
KW - Scandium
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U2 - 10.1016/j.msea.2010.02.027
DO - 10.1016/j.msea.2010.02.027
M3 - Article
AN - SCOPUS:77950859691
VL - 527
SP - 3501
EP - 3509
JO - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
JF - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
SN - 0921-5093
IS - 15
ER -