Chemical and morphological changes at Al{sub 2}O{sub 3}/NiAl interfaces and their relationship to scale adhesion

摘要: Ni-(40,50)at%Al alloys with different C and S contents were oxidized at 1000-1150 for various times in oxygen. Auger electron microscopy was used to study the interface chemistry after scale spallation ultra high vacuum. The interfacial failure stresses determined a tensile pull tester they related pore density. Results show that sulfur did not segregate Al{sub 2}O{sub 3}/Ni50Al even extended oxidation times. Small amounts, however, segregated 3}/Ni40Al interface. difference behavior may be surface energy between Ni50Al Ni40Al. On void faces of Ni50Al, first segregated, then it replaced by longer times; amount segregants varied crystallographic orientation face. Ni40Al, much earlier on due faster diffusion rate Ni-rich NiAl. apparent diffusivity Ni40Al 1000 10{sup -9} 6 x cm{sup 2}/s respectively. Excess greatly increased Preliminary results stress showed decreased increasing density, regardless whether present interface, indicating major detrimental effect adhesion enhance formation.