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NASA CONTRACTOR
RWORT
NASA CR-
CHARACTER IZAT ION OF N ICKEL-COPPER ALLOY SPEC IMENS
PROCESSED AS A PART OF THE M553 SPHERE FORMING
EXPERIMENT DURING THE SKYLAB 1 AND 2 FLIGHT
By J. L. Hubbard, J. W. Johnson, and J. L. Browki Georgia Institute of Technolorn Atlanta, Georgia 30332
December 1973
( N A S A - C H - 1 2 9 C 3 9 ) CHAEkCT3RIZBTIOY OF N74-348? N I C K E L - C C P P E F ALLCY SPECI!IENS PROCESSED AS A P A R? O F T h E M553 S P H E b E FOat3ING E X P E R I M E N T C V E I N G TkZ S K Y L A B? (Georgia Uiiclas inst. o f Tecn.) 32 p iiC 6 3. 2 5 C S C L 1 3 H C3/15 SlCSG
Prepared for
N A S A - G E O R G E C. MARSHALL S P A C E F L I G H T C E N T E R Marshall Space Flight Center, Alabama 35812
T E C H N I C 1 REPORT NO. 2. GOVERNMENT ACCESSION NO. NASA C R - 129099
I
AND C h a r a c t e r i z a t i o n o f Nickel-Copper A l l o y Specimens P r o c e s s e d a s a P a r t of t h e M553 S p h e r e Forming Experiment During t h e Skylab 112 F l i g h t iL 1 AUTHOR(S) J. L. llubbard, J. W. Johnson, J. L. Brown J I 9 P E R F O R M I N G O R G A N I Z A T I O N N A M E AND ADDRESS I Georgia Institute of Technology I 1 A t l a n h , Georgia 30332
12 SPONSORING^ AGENCY^ N A M E^ ANC^ ADDRESS N a t i o n a l A e r o n a u t i c s and Space A d m i n i s t r a t i o n Washington, D. C. 20546
- R E P O R T S T A N D A R D T I T L E P A G E 3. R E C l P l E N T ' S CATALOG NO.
5. REPORT D A T E
8. P E R F O R M I N G ORGANIZATION REPOR r U
1 0. WORK U N I T NO.
I
1 1. CONTRACT OR GRANT NO. NAS 8-
C o n t r a c t o r Report Summary
I-- I ! 5 S U P P L E M E N T A R Y N O T E S I I 1^ i - ( 1 6. ARSTRACT I Two specimens o f a n i c k e l - c o p p e r a l l o y were p r o c e s s e d a s a p a r t of t h e M553 Sphere Forming Experiment d u r i n g t h e Skylab 1 1 2 f l i g h t. Both o f t h e s e specimens were a p p a r e n t l y c o m p l e t e l y melted by t h e e l e c t r o n beam i n t h e Skylab M512 M a t e r i a l s i P r o c e s s i n g F a c i l i t y and e i t h e r f l o a t e d free i n s p a c e , but c o l l i d e d w i t h some smooth f l a t s u r f a c e b e f o r e s o l i d i f y i n g o r remained a t t a c h e d t o i t s s u p p o r t p o s t d u r i n g s o l i d i f i c a t i o n. (^) Both specimens had a smooth f l a t a r e a on t h e s u r f a c e due
! t o t h i s a d h e r e n c e d u r i n g s o l i d i f i c a t i o n.
I; The nominal composition of t h i s a l l o y b e f o r e p r o c e s s i n g i n s p a c e was 70 p e r c e n t
j N i , 30 p e r c e n t Cu. T e s t s have shown t h a t a c o n s i d e r a b l e amount o f copper was l o s t , d u r i n g p r o c e s s i n g by e v a p o r a t i o n. It was f u r t h e r found t h a t less copper was ; p r e s e n t^ i n^ t h e^ c a p a r e a s ,^ p a r t i c u l a r l y^ a t^ t h e^ s u r f a c e ,^ t h a n was^ i n^ t h e^ remainder^ of t h e specimens. The m i c r o c h e m i e t r y o f t h e d e n d r i t e s and i n t e r d e n d r i t i c r e g i o n s however, is i n agreement w i t h t h e p h a s e d i a g r a m f o r t h i s a l l o y.
I
The measured d e n s i t i e s o f t h e s e specimens were l e s s t h a n t h e t h e o r e t i c a l d e n s i t y of t k i s a l l o y due t o t h e amount o f p o r o s i t y p r e s e n t , however, no l a r g e v o i d s were found by r a d i o g r c p h i c t e c h n i q u e s.
I 1 U n c l a s s i f i e d - U n l i m i t e d I
! " 7 KEY WORDS !
I U n c l a s s i f i e d ( U n c l a s s i f i e d 1 31 1 NTIS I
18. D I S T R I B U T I O N S T A T E M E N T
.CS. - LL') 11 ' (ofchi. n~cm 2 0. SECURIT Y C L A S S I F. (of thin peso)
I I I I J
!SIT - b ' r ~ r m 3 2 9 2 t R r r December 1 9 1 2 ) For sale hy N a t i o n a l Technical I n f o r m a l i n n S o v i c e , SpringlitlJ. Virginia 2 2 I 5 1
21. NO. OF P A b F S 2 2. P R I C E
I
LIST OF ILLUSTRATIONS
FLgure Title Page
I. Profile view of Specimen SL-1.8 ( 10X).............. 11
2. Profile view of ground base Specimen 2-10 (10X)........ 11
3. Scanning electron micrograph taken normal to flat area on
Specimen SL-1.8 (8SX)..................... 12
4. Scanning electron micrograph of columnar dendrites on the surface of Specimen SL-1.8 (25X)................ 12 5. Scanning electron micrograph of columnar dendrites cn the surface of Specimen SL-1.8 (250X)................ 13 6. Scanning electron micrograph showing the three surface texturns on Specimen SL-1.8 (25X)................ 13 9. Scanning electron micrograph of the abrupt transition from the porous band to the cap area in Specimen SL-1.8 (25OX)... 14 8. Scanning electron micrograph of the abrupt transition from the porous band to the cap area in Specimen SL-1.8 (250X)... 14 9. Scanning electron micrograph of the circular dendrites in the cap region of Specimen SL-1.8 (250X).............. 15 10. Scanning electron micrograph of the circular dendritea in the cap region of Specimen SL-1.8 (250X).............. 15 11. Oblique view of the cap boundary on Specimen^ SL-1.8^ (25X).^^ ..^16
12. Oblique view of the cap boundary on Specimen SL-1.8 (100X).. 16
13. Ogtlcal macrograph of the poliehed and etched c r o s s section of Speulmsn SL-1.8 (SOX). (^).................... 17
LIST OF iLLUSTRATIONS (Continued)
Figure Title Page
- Scanning^ electron^ micrograph^ n*^ the c r o s s section of Specimen SL-1.8 near the cap region (100X)............ 17
- Optical micrograph of the c r o s s section of Specimen SL-1. near the porous baud ( 100X).................... 18
- Scanning electron micrograph of the c r o s s section of Specimen SL-1.8 near the porous band ( 100X).......... 18
- Optical micrograph of the c r o s s section of Specimen SL-1. in the equiaxed dendritic region (100X)..............^19
- Scanning electron micrograph of the c r o s s section of Specimen SL-1.8 in the equiaxed dendritic region (250X)..... 19
- Optical micrograph of the columnar dendrites in the c r o s s section of Specimen SL-1.8 (100X)................^20
- Scanning electron micrograph of the columnar dendrites in the c r o s s section of Specimen SL-1.8 (100X).......... 20
- Profile view of Specimen SL-1.7 (10X).............. 21
- Scanning^ electron micrograph of columnar dendrites on the surface of Specimen SL-1.7 (400X)...............^21
- Scanning electron micrograph of the dendrites in the porous band on Specimen SL-1.7 (750X)................ 22
- Scanning electron micrograph of the edge of the cap region on Specimen SL-L 7 (150X)..................^22 25. Scanning electron micrograph of the circular dendrites in the cap region of Specimen SL-1.7 (750X).............^23
SUMMARY
i'wo epecimens of a nickel-copper alloy were processed a s a part of the ME69 Sphere Forming Experiment during the Skylab l/2 flight. Both of these epecimens were apparently completely melted by the electron beam in the Skylab MSl2 Materials Processing Facility and either floated free in space, but collided with eome smooth flat surface before solidifying o r remained at- tached to its mpport post during solidification. Both specimens had a smooth
flat area on the surface due to this adherence during solidification.
Solidification began from the flat contact region with the growth of columnar dendrites which extend from the flat ragion through about one third of the specimen. This columnar dendritic region is followed by a region of randomly oriented equiaxed dendrites. A large amount of porosity is asso- ciated with these dendrites on the surface of the specimens due to solidifica- tion shrinkage. The portion of the sample surface directly opposite the flat
region is covered with a continuous cap made up of fine circular dendrites.
The nominal composition of this alloy before processing in space was
70 percent Ni, 30 percent Cu. Tests have shown that a considerable amount of
copper was lost during processing by evaporation. It was further found that
less copper was present in the cap areas, particularly a t the surface, than
was in the remainder of the specimens. The microchemistry of the dss:!,ites and interdendritic regions however, is in agreement with the phase diagram for this alloy.
The measured densities of these specimens were less than the theore- t i c d density of this alloy due to the amount of porosity present, however, no large voids were found by radiographic techniques.
There was some contamination on the surfaces of these specimens.
Some of this was attributable to particles from the support posta but the re-
mainder is unexplained.
CHARACTERIZATION PROCEDURES
Visual Observations
Each of the Skylab specimens was carefully observed under a stereo
microscope. Precise notes were taken concerning the shape of the specimens,
the degree of mdting, the presence of surface contaminants, and the position
and nature of any unusual features.
Optical Macroscopy
Optical mac.mgmphs were taken of each of the specimens from a t least
four WFerent orthogonal directions. These macrographs were taken on a
Bausch Bs Lomt "Ltt a m e r a using a 48 millimeter Mlcro Tessar lens o r on
a Polaroid MP-3 camera setup. A few stereomacrographs were recorded
using a 6 degree tilt between the left and right views.
Radiography
Radiographs of each of the specimens were made using a Baltograph II
x-ray generator operating at 155 KV with a tungsten target to reveal the posi-
tion and ~ i z eof any voids present.
Sphericity
Sphericity measurements were made using a micrometric technique
which is reported in the results as the ratio of the maximum radius to the
minimum radius of the specimen.
Density
The density was measured using a buoyancy technique comparing the
weight of the specimen in air and in water. Because of the porosity on the
surface of the specimen, ultrasonics was used to facilitate complete wetting of the specimen by the water.
Grain 8be Measurements
The Laue grain size was meamred from a pattern obtained with a
Laue pin hole camera back reflection technique. A Picker x-ray generator
wire aaw. After aectionlng, one BLalf of each of the ergecirnena waa mounted
in a casting r e d n ero that the cut b e could be prepared for examination. The
gecimens were mechnically goliehed ueing a aeries of abrasive papers and
wet poliehlng wheels through a 0.8 micron alumina. Specimen SL-l,8 was
dectropoliehed using a Ma-Electfopolisher. ElecLropoliaMng was =corn-
glished using the E2 d w t r o l y t e solution containing:
Cupric nitrate 0.5 kg
Concentrated HN09 30 x 10*mS
ethyl alcohol goo x lo4 ma
The sections were etched after electron microprobe analysis was per-
formed. S p e c h e n SL-1.8 ms etohed with Carapellats reagent containing:
Ferric chloride 5 x 10"kg
Concentrated HCL 2 x 10-@ma
Methyl alcohol 99 x 10dms
Specimen SL-1.7 was etched using:
Concentrated HNO, 50 percent
Glacial Acetic Acid 50 percent
Lattice Parameter and Curie roint Measurements
The lattice parameter was measured using an x-ray diffractometer
technique on the section of the specimen. The Curie h i n t was measured
using a DuPont 900 differential scanning calorimeter.
Emission Spectroscopy
A small amount of material was removed from the center of the un-
mounted half of each specimen by drilling a small shallow hole in the center
of each cut h e. The shavings thus produced were placed in a cavity of a
carbon spectrographic rod and burned to completion in an Applied Research
Laboratories 1.5 meter grating emisaim spectrograph. The near ultravia-
let radiation was recorded on Kodak Spectrum Analysi~lNo. 1 Film and ana-
lyzed on an Applied Research Laboratories comparator,
Electron Probe Microanalysis of Sections
Each of the polished sections was analyzed in the electron microprobe.
Analyses were made of general areas of the sections, across grains, ir .I .,!
dong dendritic features, in eutectics and in any unusual features seen. Stan-
dards supplied by Dr. Theo Kattamis of the University of Connecticut were used to obtain quantitative data irom these a d y ass.
Optical Examination of Specimen Sections
Optical macrographs of each of the polished and etched sections were
taken using a Bausch and Lomb "Lff camera and a 48 millimeter lens o r a
Polaroid MP-3 camera setup, Micrographs were taken to demonstrate all of
the various microstructures present on each section using a Leitz Metallux o r
a Reichsrt Metallograph optical microscope.
Scanning Electron Microscopy of Sections
Each of the specimen sections was removed from its mount and placed in the scanning electron microscope for observation. Micrographs were taken of both typical and unusual features and some nondispersive x-ray analyses were performed.
particles analyzed using energy dispersive x-ray analysis:
Al, Si, S, Cl, K,Ca, Ag and Ti
A number of A1203 particles were identified on the surface using elec- tron microprobe analysis. Quantitative analysis from randomly selected
spots on the surface showed a large variation in the amount of copper present
from a hlgh of 27.6 percent to a low of 6.1 percent. No pattern of Cu content
versus surface position o r s u r ' c!e features was found.
X-ray spectroscopy analysis shows the Cu concentration in this sample
as a whole to be 23.2 percent. This antilysis, of course, is representative
more of the surface of the sample than of the interior.
Emission spectrographic analysis of some of the material from the center of the specimen grave the following trace elemental content:
Fe - 20 PPM
Pb - 5 PPM
Ca - 6 PPM
Electron microprobe analysis from selected areas on the specimen
c r o s s section &owed the copper concentration near the flat side and in the center to be almost equal and averaged 28.4 percent. In the region near the cap, however, tho average dropped to 25.6 percent.
Figure 1 3 is an optical macrograph of the polished and etched c r o s s
section of Specimen SL-L 8. Optical ar,d scanning e l x t r o n micrographs of
the microstructuree are shown in Figures 14 through 20. Figure 14 shows
the microstructure in the cap region of the specimen. The porosity and mic-
rostructure associated with the external porous band are shown in Figures
15 and 16, The random oquiaxed dendrites in the center of the section a r e shown in Figures 17 and^18 and the columnar dendrites near the flat region
are e h w n in Figures 19 and 20.
Specimen 8L-1.
Specimen SL-1.7 is a nickel-copper alloy and resembles Specimen
SL-1.8 very closely as seen in Figure 21. It has a smooth flat side and the
three regions of surface topography previously described for Specimen SL-1.8.
The dendty of Specimen SL-1.7 was measured to be 8.97 x 1 Fkg/m3.
The sphericity was found to be 1.08 (Rmax/Rmln).
The Laue grain size was measured to be somewhat g ~ e a t e rthan
1 x 10%. The surface grain size was meamred in the cap area and in the
porous area of free dendrites. in the cap area the dendrites measured
6.7 x lo+ and in the free dendrite area they measured 7 x 10-%(&5 x lo*).
Figure 22 is a scanning electron micrograph of the surface of Speci-
men SL-1.7 in the columnar dendritic region. The structure id the more por-
ous band is shown in Flgure 23 and the boundary region between the porous
band and the cap area is shown in Figure 24. Figures 25 and 26 show the
surface structure of the cap area.
Energy dispersive analyses of a number of areas on the surface of the
specimen showed the following contaminating elements:
Al, W, Ag, Sn, Fe, and C r
The copper content in the cap area was analyzed in the electron micro-
probe. An overall analysis in the area gave the copper content to be 9.05 per- cent. Point analyses along these surface dendrites ehowed a variation accor-
ding to the growth pattern from a high of 11.53 percent to a low of 7.82 per-
cent.
Microprobe analyses from areas on the cross section of this specimen
ahowed a general decrease in the amount of copper present in dendrites as
analysis proceeded from the flat region toward the cap region. The average
copper content in dendrites in areas other than the cap region was 25.4 per-
cent. In^ interdendritic^ points^ it^ averaged 42.3 percent.^ In^ o r near the^ sap
area the copper content in the dendrites measured to be 22.5 percent and in
interdendritk spots it was 41.2 percent. Quantitative andyses were also
made in the electron microprobe along radii of the cross section in both the central dendritic portion and in the cap area aP the specimen. Figure 27 is a graph of the copper concentration vgreus distance from the specimen sur-
face in the central dendritic region. The mlnimas on this graph reprersent
DISCUSSION OF RESULTS
The internal microstructures and external appearances of the nickel-
copper alloy specimens processed in near zero gravity are very similar to
those found on the ground test specimens of the same alloy. The three sur- face textures, the smooth columnar dendrites, the - ed dendrites in a
porous band, and the continuous cap of fine circular dendrites, are present
in specimens from both experiments and comprise approximately the same
areas in all specimens. The columnar dendrites grew in all cases as a re-
sult of the temperature gradient created by the contact of the specimens with some other surface. None of the specimens solidified in free flight. In the microstructures seen in the cross sections of these specimens the columnar
dendrites appear slightly larger in the near zero gravity specimens than they
do in the ground base specimens. As solidification continued the temperature
gradient lessened and the columnar dendritic growth gave way to the growth of the randomly oriented equiaxed dendrites. The porosity seen on the surfaces of the specimens in the a r e a of these equiaxed dendrites is due to solidifica- tion shrinkage. At some time before f i n d solidification of the specimen the
cap area of tttwo-dimensional" circular dendrites was formed. This area is
free of porosity and is typical of chilled surfaces formed on castings.
There is evidence that more copper was lost by evaporation in the
specimens processed in near zero gravity conditions but this is clouded by the fact that the ground base specimens contained unmelted portions.
The microsegregation in the dendritic and interdendritic regions is not unusual and is in agreement with the phase diagram for this alloy. No large voids were found in the interior of any of these specimens.
Georgia Tech Figure 1. Profile view of Sl~ecimen SL-1. S i 10S).
Georgia 'I'cck Figure 2. Profile view of groulld base Sl~ecimen2-10 (10S).
Georgia 'I'ech Figure 5. Scanning electron microg~*aphof columnar dendrites on the surface of St~ecimenSL-1. S ( 2 5 O S ).
Georgia Tech Figure 6. Scanning c4cctron micrograph showing t h e three s ~ ~ r f a c e textures on Sl)ecimen SL-1.8 (25X).
G e o r g i a 'l'c!ch Figure 7. Scanning electron micrograph of the abrupt transition from the porous band to the cap area in Specimen S1,-1. S (25US).
Georgia Tech I Figure 8. Scanning electron m icrogl-a1111of Lhc :tbrul)t Lransi tion from the porous band to the cap area in Specimen SL-1. S (250X).
