Specific weight changes of nickel-base superalloy B-1900 and B-1900 + 1% Si specimens were tested at 1273 K. B-1900 was losing weight at an increasing rate due to spalling of oxide scale while B-1900 + 1% Si was still gaining weight at low, nearly constant rate. Similar comparison in weight change was observed for specimens tested at 1373 K

Lowell, C. E.

Miner, R. V., Jr.

English

NASA Technical Reports Server

March 1974	 1	 B74-10007 
NASA TECH BRIEF 
Lewis Research Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service. Springfield. Virginia 22151. Requests for individual copes or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Addition of Silicon Improves

Oxidation Resistance of Nickel Based Superalloys 
.
The addition of one weight percent silicon to the 
nickel-base superalloy B-1900 (nominal composition in 
weight percent: 0.10 carbon, 8.0 chromium, 10.0 cobalt, 
6.0 molybdenum, 1.0 titanium, 6.0 aluminum, 0.015 
boron, 0.10 zirconium, 4.0 tantalum, with balance nickel) 
has been shown to markedly improve its cyclic oxidation 
resistance. 
B-1900 and B-1900 + 1% Si were tested by cyclic 
heating in air to 1273 K (1832°F) and 1373 K(20l2°F) 
for 7000 and 2000 cycles, respectively. Each cycle 
consisted of 6 minutes in the furnace and 9 minutes 
cooling in still air. Thus, total heating times were 700 and 
200 hours at, respectively, 1273 K (1832°F) and 1373 K 
(2012°F). 
Specific weight change of B-1900 and B . 1900 + 1% Si 
specimens tested at 1273 K (1832°F) is shown as a 
function of heating cycles in the figure. At the end of the 
test, B-1900 was losing weight at an increasing rate due to 
spalling of the oxide scale while B-1900 + 1% Si was still 
gaining weight at a low, nearly constant rate. A similar 
comparison in weight change was observed for the 
specimens tested at 1373 K (20120F). 
Metallographic examination of the oxidized specimens 
showed that below the oxide scale the depth of alloy 
depleted in the strengthening gamma prime phase was 
much less in B-1900 with silicon added. 
10 
C'd	 U 
E 
S 
.2'
-20 
-20 
• 
ia
	 200	 flt
	
400
	 500	 601	 7 (10M	 1203)
	 OD00	 (4	 15033	 I6	 I7 
Exposure time, hr (cycle) 
Theeffect o Sion the resistance to cyclic oxIdatIon of 8-1911 at 1273K (1832°F).
In earlier work, it was shown that the addition of 
silicon greatly improves the cyclic oxidation resistance of 
trinickel aluminum, Ni 3
 Al, the basis of the gamma prime 
phase in nickel-base superalloys. Since the same effect has. 
been observed in B.-1900, an alloy which contains about 
60 volume percent gamma prime, there is promise that 
silicon may also provide improved oxidation resistance for 
other gamma-prime-strengthened nickel-base superalloys. 
It must be pointed out, however, that silicon is 
commonly held to be damaging to the mechanical 
properties of nickel-base superalloys. It is normally 
present in these alloys only as a "tramp" element and 
maximum concentrations of a few tenths percent are 
allowed by alloy specifications. It is not clear in how 
many of these alloys silicon has been demonstrated to be 
detrimental. Regardless of this question, the possible 
improvement in oxidation resistance due to silicon would 
appear to be ample justification for studying the effects of 
controlled silicon additions in the development of new 
high temperature alloys. 
Notes: 
I. Further information is available in the following 
reports: 
NASA TM-X-68191 (N73-16564), Improvement in 
Cyclic Oxidation of the Nickel-Base Superalloy 
B-1900 by the Addition of One Percent Silicon 
NASA TN-D-6838 (N72-26434), The 1200°C 
Cyclic Oxidation Behavior of Two Nickel-
Aluminum Alloys (Ni3
 Al and NiAl) with Additions 
of Chromium, Silicon, and Titanium 
Copies may be obtained at cost from: 
Aerospace Research Applications Center 
Indiana University 
400 East Seventh Street 
Bloomington, Indiana 47401 
Telephone: 812-337-7833 
Reference: B74-10007
(continued overleaf) 
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	 will be free from privately owned rights.
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2. Specific technical questions may be directed to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B74-10007 
Patent Status: 
NASA has decided not to apply for a patent. 
Source: C.E. Lowell and R.V. Miner, Jr. 
Lewis Research Center
(LEW-1 2138)
. 
. 
S 
B74-10007	 Category 04


Addition of silicon improves oxidation resistance of nickel based superalloys

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