24-10-2012, 11:35 AM
Chemical and Morphological Changes at Al(2)O(3)/NiAl Interfaces and Their Relationship to Scale Adhesion
ABSTRACT
Ni-(40,50)at%Al alloys with different C and S contents were oxidized at 1000-1150 C for various times in oxygen. Auger
electron microscopy was used to study the interface chemistry after scale spallation in ultra high vacuum. The interfacial
failure stresses were determined with a tensile pull tester and they were related to the interfacial pore density. Results show
that sulfur did not segregate to the Al(sub 2)O(sub 3)/Ni50Al interface even after extended oxidation times. Small amounts,
however, segregated to the Al(sub 2)O(sub 3)/Ni40Al interface. The difference in behavior may be related to the surface
energy difference between Ni50Al and Ni40Al.
ABSTRACT
Ni-(40,50)at%Al alloys with different C and S contents were oxidized at 1000-1150 C for various times in oxygen. Auger
electron microscopy was used to study the interface chemistry after scale spallation in ultra high vacuum. The interfacial
failure stresses were determined with a tensile pull tester and they were related to the interfacial pore density. Results show
that sulfur did not segregate to the Al(sub 2)O(sub 3)/Ni50Al interface even after extended oxidation times. Small amounts,
however, segregated to the Al(sub 2)O(sub 3)/Ni40Al interface. The difference in behavior may be related to the surface
energy difference between Ni50Al and Ni40Al.