Several oxide dispersion strengthened (ODS) alloys were tested for cyclic, high velocity, oxidation, and hot corrosion resistance. These results were compared to the resistance of an advanced, NiCrAl coated superalloy. An ODS FeCrAl were identified as having sufficient oxidation and hot corrosion resistance to allow potential use in an aircraft gas turbine without coating

Deadmore, D. L.

Lowell, C. E.

English

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NASA TECHNICAL	 NASA TM X-73656MEMORANDUM
AN.-m
%0	 177-23240 
3656) HIGH V'^LO:ITY CXIDX.T?O(N6SA-"-''^!-X-7	 RHSIST&HCS OF SOME GDS
i	 XND HO CORfi3656)	 MF k^71	 CSCL 11F
X	 ALLOYS (N?.SA) 19 P HC X42/
	
Unclas
G3/2b 29076
a
az
HIGH VELOCITY OXIDATION AND HOT CORROSION
RESISTANCE OF SOME ODS ALLOYS
by Carl E. Lowell and Daniel L. Deadmore
Lewis Research Center
Cleveland, Ohio 44135
April 1977
NA3A STI FAMUTY.
IdFUT BRANCH	 f'
:4r
-1
1.	 Report No. 2. Government Accession No. 3.	 Recipient's Catalog No.
NASA TM X-73656
4. Title and Subtitle 5. Report Date
HIGH VELOCITY OXIDATION AND HOT CORROSION
6. Performing Organization Code
RESISTANCE OF SOME ODS ALLOYS
7. Author(s) S. Performing Organization Report No.
Carl E. Lowell and Daniel L. Deadmore E-9172
10, Work Unit No.
9. Performing Organization Name and Address
Lewis Research Center 11. Contract or Grant No.
National Aeronautics and Space Administration
Cleveland, Ohio 44135 13. Type of Repor and Period Covered
Technical Memorandum12. Sponsoring Agency Name and Address
National Aeronautics and Space Administration
Washington, D.C.	 20546
14. sponsoring Agency code
15. Supplementary Notes
16. Abstract
Several oxide dispersion strengthened (ODS) alloys were tested for cyclic, high velocity, oxida-
tion and hot corrosion resistance. 	 These results were compared to the resistance of an ad-
vanced, NiCrAI coated superalloy. An ODS NiCrAI and an JD: FeCrAI were identified as having
sufficient oxidation and hot corrosion resistance to allow potential use in an aircraft gas turbine
without coating.
17. Key Words (Suggested by Author(s)) 18, Distribution Statement
Oxidation Unclassified - unlimited
Hot corrosion
Dispersion strengthening
Nickel alloys
19.	 Security Clastif. (of this report) 20.	 Security Classif. (of this page) 21. No. of Pages 22.	 Price'
Unclassified Unclassified
' For sale by the National Technical Information Service, Springfield, Vilgmia 22161
HIGH VELOCITY OXIDATION AND HOT CORROSION
RESISTANCE OF SOME ODS ALLOYS
by Carl E. Lowell and Daniel L. Deadmore
Lewis Research Center
SUMMARY
High velocity, cyclic oxidation tests were conducted on several uncoated ODS
alloys at 11000 C for times to 3000 hours. Oxidation resistance of these materials
was compared to that of MM200 coated with an advanced NiCrAI coating. The alloys
evaluated were a FeCrAI (MA-956), NiCrAl with Fe (MA-953) and two NiCrAls
(HA-8077 and HA-8077 modified with additional Al). The MA-956 and HA-8077 had
oxidation resistance comparable to the coated superalloy while the modified HA-8077
was slightly less resistant and the MA-953 was much less resistant to oxidation than
any of the other alloys. All but the MA-953 were judged sufficiently oxidation resis-
tant for use as aircraft gas turbine vanes in applications involving maximum metal
temperatures of 1100 0 C.
The same alloys plus tantalum-modified HA-8077 were tested in an accelerated
high velocity, hot corrosion test at 900 0 C. MA-956 was more corrosion resistant
than any other material tested including the coated MM200. HA-8077 and HA-8077
with additional Al were less resistant to hot corrosion than the coated MM200 but
still were exceptionally good. The tantalum-modified alloys and MA-953, while
substantially better than conventional superalloys, were much less resistant than the
NiCrAls without tantalum or iron. These results suggest that hot corrosion shoulci
not limit life (at least to 3000 hr) of the NiCrAls or the FeCrAI in aircraft turbine
applications.
INTRODUCTION
Several oxide dispersion strengthened (ODS) alloys have been developed with po-
tential for use as aircraft turbine vanes at temperatures to 11000 C. (Oxidation and
hot corrosion test results are given in ref. 1.) This work indicated that Y203
strengthened NiCrAls had excellent oxidation and hot corrosion resistance in short
time (-200 hr) tests. Other work (ref. 2) indicated that a Y 203 strengthened FeCrAI
had even more promise in oxidation/hot corrosion but was questionable in terms of
having sufficient high temperature strength. The purpose of this work was to deter-
mine the oxidation resistance of these and other ODS alloys for times to 3000 hours
STAR Category 26
I
2at 11000 C. Also evaluated was the hot salt corrosion resistance of these alloys at
9000
 C for times to 2000 hours. All samples were tested cyclically in a Mach 0.3
burner rig. The resistance of the alloys was judged by change in weight (Aw), metal
thickness loss (At), and metallography. The alloys investigated were primarily ODS
NiCrAls with and without quaternary additions and wi ODS FeCrAl. A commercial
superalloy (MM-200) with an advanced NiCrAI coating was tested simultaneously for 	 ...
comparison.
MATERIALS AND PROCEDURES
The alloys tested in this program and their compositions are listed in table I.
HA-8077 is a commercial ODS NiCrAI while AT-264, AT-265, and AT-266 are modi-
fications of HA-8077, AT-264 has slightly more aluminum than HA-8077 and was
identified as superior to it in reference 1. AT-265 and AT-266 Pre nominally the
same composition as AT-264 except that they contain tantalum. MA-953 is an La203
strengthened NiCrAI with 35 w/o iron added while AIA-956 is basically an ODS FeCrAl.
All of these alloys were received in the as-extruded and hot worked condition. They
were machined to the shape shown in figure 1. The NiCrAl coated MAI--200 samples
were received from a commercial vendor. All samples were weighed to t0.2 milli-
gram (mg) and their diameters measured to fl micrometer (µm).
The burner rib used for these tests is shown in figure 2; it has been fully de-
scribed in several reports from this laboratory (e, g., ref. 3). The oxidation tests
were run with JP-5 fuel combusted and expanded through the nozzle at Mach 0.3.
Each cycle consisted of 1 hour in the flame at 1100 0 C metal temperature followed by
a 3-minute cooling in forced air. The samples were weighed once a day. Oxidation
samples were run until failure (loss of >50 mg/cm 2) or 3000 cycles. After removal
from test each sample was photographed, sectioned (A-A in fig. 1), and mounted for
metallography. Unaffected metal thickness was measured with a traveling micro-
scope for a determination of thickness change, At. All samples were run in duplicate.
Hot corrosion tests were conducted in the same type of rig using the same duty
cycle but with a temperature of 900 0 C. A water solution of synthetic sea salt (see
table II for its composition) was added to the combustion products in the combustion
chamber to a level of 5 parts per million by weight of combustion air. After every
15 cycles the samples were weighed, washed in distilled water and weighed again.
As in the oxidation tests samples were removed after their washed weight had
reached — -50 mg/cm 2 and were then photographed, sectioned, and metal lographi cal I y
mounted for At measurements and microstructural evaluation.
3RESULTS AND DISCUSSION
Oxidation
Because of the longer times to failure, fewer alloys were tested in oxidation
than in hot corrosion. The AW data are plotted in figure 3 along with some burner
rig data on TD-NiCr (ref. 4) for comparison. MA-953 was the first allov to fail
	 ...
(600 - 800 cycles). Surprisingly (in light of ref. 1), the modified HA-8077 (AT-264)
was less oxidation resistant than the unmodified HA-8077 (AT-259) sample. Indeed,
HA-8077 (AT-259) showed only i0 mg/cm2 loss at the conclusion of the test (3000
cycles). The ODS FeCrAI (MA-956) showed little evidence of attack (-2 mg/cm2)
even at 3790 cycles. There was a slight weight gain (2 mg/cm2) on the coated
MM-200 at 3790 cycles.
The appearance of the alloys, as shown in figure 4 confirms the impression re-
ceived from AW data except in the case of the coated alloy. The coating on one of
the two duplicates showed substantial coating failure due to pitting. Even though at
the conclusion of the test the coated samples showed little weight change, it is obvi-
ous that the coating has little life left. Further confirmation is given by the metal-
lography in figure 5. Except for a small recrystallized zone at the surface, the ODS
FeCrAI shows little evidence of the prolonged oxidation exposure. The HA-8077
(AT-259) looks as good as the ODS FeCrAI except for some void formation. Both the
MA-953 and the AT-264 (modified HA-8077) show extensive oxide penetration, while
the coated MM-200 showed isolated oxide penetration of the coating.
The At data in table III(a) ai, still further confirmation of the results. Both
the MA-953 and the modified HA-8077 show substantial metal loss while the HA-8077
(AT-259) had only minor metal recession and the At measured on the ODS FeCrAI
was at the limit of detection. It should be noted that all of the alloys with the possible
exception of MA-953 were shown .,) have excellent oxidation resistance when com-
pared to most uncoated superalloys.
Hot Corrosion
The OW data for the hot corrosion tests are plotted in figure 6. This is an ac-
celerated test as can be seen from the data for IN-792 (ref. 3) which is plotted for
comparison. This alloy is generally considered to have relatively good hot corrosion
resistance, but under the conditions of this test its life is less than 150 hours. The
alloys tested here fell into three groups in terms of hot corrosion life. The least re-
sistant were MA-953 and the two tantalum modifications of HA-8077 (AT-265 and
AT-266). Their lives were about 400 hours. Substantially more resistant were the
4ODS NiCrAls without tantalum (HA-8077 and aluminum modified HA-8077 (AT-264).
Their lives were about 1100 hours with the unmodified alloy life being slightly longer.
Finally, the ODS FeCrAI showed no indication of failure after 2313 cycles. The coat-
ings on MM-200 failed locally after approximately 1200 hours.
The appearance of the samples (fig. 7) and their metallography (fig. 8) confirm
that the samples had indeed failed by the conclusion of their test time. The single
exception was ODS FeCrAI which showed no external or microstructural evidence of
even having been in test. More confirmation is shown by this At data in table III(b).
As in the oxidation tests the At for ODS FeCrAI is the same as the error in the
measurement.
As in the case of the oxidation data, it must be stressed that all the alloys tested
are excellent in hot corrosion when compared to conventional bare superalloys. In
fact the ODS FeCrAI and the two ODS NiCrAls without quaternary additions probably
have enough hot corrosion life for vane service in most aircraft turbines.
CONCLUDING REMARKS
As a result of high velocity cyclic testing for oxidation at 1100 0 C and hot corro-
sion at 9000 C, several observations can be made. In general, uncoated ODS NiCrAls
and ODS FeCrAI have sufficient oxidation resistance for long time service at a metal
temperature of 11000 C. They also have excellent hot corrosion resistance; the
limits of ODS FeCrAI were not reached in this study. It remains to be demonstrated
whether or not these alloys have sufficient high temperature strength and thermal
fatigue resistance for vane applications. If they do have the latter properties, these
alloys could find use not only in aircraft gas turbines but also in ground power tur-
bines as well. These tests also indicate a great potential of FeCrAI alleys for hot
corrosion resistance which might be realized by using such compositions for coating
or cladding.
REFERENCES
1. Deadmore, Daniel L.; Lowell, Carl E.; and Santora, Gilbert J.: High Gas Velocity
Oxidation and Hot Corrosion Testing of Oxide Dispersion-Strengthened Nickel- Base
Alloys. NASA TM X-71835, 1975.
Ti
2. Whittenberger, J. D.: Creep and Tensile Properties of Several Oxide- Dispersion-
Strengthened Nickel-Base Alloys at 1365 K. NASA TN D-8422, 1977.
3. Lowell, Carl E.; and Deadmore, Daniel L.: Effect of a Chromium-Containing Fuel
Additive on Hot Corrosion. NASA TM X-73465, 1976.
54. Johnston, James R.; and Ashbrook, Richard L.: Oxidation and Thermal Fatigue
Cracking of Nickel- and Cobalt-Base Alloys in a High Velocity Gas Stream.
NASA TN D-5376, 1969.
6TABLE I. - ALLOY ANALYSIS IN WEIGHT PERCENT
1 
Element I AT-259 AT-264 AT-265 AT-2661 MA-953a MA-956(HA- 8077)
Al 4.17 4.54 4.7 4.9 5.5 4.40
Cr 15.7 15.7 16.0 15.9 21 18.9
Ni Bal. Bal. Bal. Bal. Bal. 0.4
Fe ---- ---- ---- 35 Bal.
Ta ---- ----- 1, 7 1.2 --- ----
Yb 1.6 1.5 1.5 1.5 --- 0.7
Co	 I ---- 1.10 0.7 0.4 --- ----
1	
Ti -- ---- 0.5 0.5
C 0.06 0.05 0.05 ++
	 0.05 --- 0.02
Lac	 I ---- ---- ---- ----	 I 0.3 ----
allominal values,
b Present as X203,
e Present as La 203*
TABLE H. - COMPOSITION OF SYNTHETIC SEA SALT
Compound	 i	 Concentration,
g/1
NaCl 24.53
A-TgC12 5.20
Na2SO4 4.09
CaCl2 1.16
KC1 i	 .695
NaHCO3 .207
KPr . 101
H3 BO3 .027
SrCl2 .025
NaF .003
7TABLE III. - METAL THICKNESS LOSS
[ All values are f0.01 mm. I
(a) Oxidation
Alloy	 Cycles Thickness change,
Ot,
mm
AT-259 (HA-8077)
AT- 264
MA-953
MA-956
3000 0.02
2993 .86
787 .40
3790 .01
(b) Hot corrosion
r --	 IAT-259 (HA-8077)	 1119 0.32
AT-264	 1220 .50
AT-265	 504 ' .45
AT-266	 i 435 .44
j MA-953 415 .19
MA-956 2313 .01
IN-792 100 .64
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FIGURE 3. CONTINUED


High Velocity Oxidation and Hot Corrosion Resistance of Some ODS Alloys

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