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In order to improve the oxidation resistance of NiAl, the
aimsave two parts: (A)nderstanding the isothermal oxidation
behavior of NiAlompound at high temperature in air; (B) using
(1)preoxidized in air, (2)thod,(3) hydrothermal anodic
oxidation, respectively, to form oxiderface of NiAl, the
effect of oxide scale on the oxidation resistance of NiAl is
Experimental results show that the oxide scale on the surface
oft >900℃ in air is alumina. The microstructure of oxide scale
is alsoncreasing oxidation temperature. Surface of NiAl
oxidized at 900℃,1000℃s dense scale of fine particle,
porous scale of blade-like particles andales containing ridged
layer grown up from the crack of inner layer, For the NiAl
specimen preoxidized at 750℃ for 2hr in air, thenntain- ng
.theta.-Al2O3 and .alpha.-Al2O3 is formed.The slower
heatingeoxidized in air, the better oxidation resistance of
NiAl. For the NiAl specimen treated by hydrothermal method at
a40℃/28atm or 48hr, the oxide scale containing NiAl2O4 and
NiO is formed.mal reatment and then cyclic oxidation at 1000℃
～ 1200℃/15hr, thethe surface f NiAl has better densification
than that of NiAl withouteatment. This result ndicates that the
hydrothermal treatment can improve thetance of NiAl. For the
NiAl specimen treated by hydrothermal anodic oxidationpplied
urrnet density of 20mA/square centimeter at 240℃ /28atm/1hr
in, the xide scale is AlOOH and NiO, respectively.
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