Microstructural studies of carbides in MAR-M247 nickel-based

IOP Conference Series Materials Science and Engineering

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Microstructural studies of carbides in MAR-M247nickel-based superalloyTo cite this article A Szczotok and K Rodak 2012 IOP Conf Ser Mater Sci Eng 35 012006

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This content was downloaded from IP address 22010067164 on 07092021 at 0852

Microstructural studies of carbides in MAR-M247 nickel-

based superalloy

A Szczotok K Rodak

Silesian Technical University Faculty of Materials Engineering and Metallurgy

Krasinskiego 8 40-019 Katowice Poland

E-mail agnieszkaszczotokpolslpl

Abstract Carbides play an important role in the strengthening of microstructures of

nickel-based superalloys Grain boundary carbides prevent or retard grain-boundary sliding and

make the grain boundary stronger Carbides can also tie up certain elements that would

otherwise promote phase instability during service Various types of carbides are possible in

the microstructure of nickel-based superalloys depending on the superalloy composition and

processing In this paper scanning electron and scanning transmission electron microscopy

studies of carbides occurring in the microstructure of polycrystalline MAR-M247 nickel-based

superalloy were carried out In the present work MC and M23C6 carbides in the MAR-M247

microstructure were examined

1 Introduction

Addition of carbon in amounts from 005 to 02 and carbide forming elements enables precipitation

of mainly M23C6 MC and M6C types carbides in the superalloys These carbide phases are not stable

Under the influence of service temperature and time they may undergo transformations changing their

kind size and morphology which affect the alloysrsquo properties at high temperatures [1]

The carbide phase precipitates have an important role on the mechanical properties of superalloys

[2-5] Discrete carbides precipitating at grain boundaries (GBs) can inhibit GB sliding and improve the

strength and creep resistance of the superalloy at elevated temperatures Primary as well as secondary

carbides strengthen superalloys making difficult grain boundary slip during creep and tying up

elements that could contribute to phase instability during exploitation of the alloy into stable phases

[6] Grain boundary slip is hindered by M23C6 carbides in favor of creep resistance Morphology of

these carbides has a significant effect on nickel-based superalloys properties Shape change of M23C6

carbides along grain boundaries from blocky to fine globular particles leads to increase of temporary

creep resistance and improvement of nickel-based superalloys plasticity [1]

The formation sequence composition and morphological evolution of MC carbide from slow to rapid

solidification conditions have been characterized in numerous works [7-10]

In general the morphology of MC carbides in an as-cast Ni-based superalloy mainly depends on its

composition and casting parameters because this type of carbide is formed during solidification of the

nickel-based superalloy Previous investigators have reported how to control the morphology of MC

carbides for superalloys [8 11] The MC carbides may break down to form M6C andor M23C6 carbides

during high temperature treatments so a size morphology and a type of a carbide can be changed

during heat treatment of the superalloy

Technologies and Properties of Modern Utilised Materials IOP PublishingIOP Conf Series Materials Science and Engineering 35 (2012) 012006 doi1010881757-899X351012006

Published under licence by IOP Publishing Ltd 1

MARndashM247 is a hafnium-modified superalloy Hafnium has been known to have a strong effect on

carbide morphology in cast alloys and subsequently on the mechanical properties [12]

Two kinds of MC carbides (precipitated along grain boundaries as well as coarse and elongated Ta

Hf W enriched) and fine M23C6 carbides were present in the microstructure of MAR-M247 superalloy

after heat treatment in the work of Wawro [13] The coarse carbides are 2 to 10 μm in diameter and the

fine carbides are 02 to 08 μm in diameter Ta and Hf enriched MC carbides predominated in the

matrix Chromiumndashrich M23C6 carbides precipitate preferentially in the periphery of MC carbides and

in the (γ + γrsquo) eutectic at grain boundaries The area fraction of the carbides in MARndashM247 superalloy

is about 24 [11]

MARndashM247 superalloy is characterized by a low plasticity in creep conditions at moderate

temperature with great stresses That problem is mainly connected with a presence of elongated

Chinese script-like MC carbides because they promote initiation and propagation of cracks [714]

Quantitative metallography methods have been applied for investigation of carbides occurring in

nickel-base superalloys [15-16] The investigations first of all aim at optimization of chemical content

of superalloys It is not uncommon to have an incomplete description of carbides in superalloys

presented in scientific works [717-19]

2 Material

The superalloy studied in this work are based on as-cast MARndashM247 nickel-based superalloy after

thermal cycling The chemical composition of the superalloy with 015 wt C content and several

carbide-forming elements is presented in table 1 MARndashM247 is strengthened by γrsquo precipitates and

carbides There is also solid-solution strengthening of the Ni matrix by the alloying elements This

material is applied mainly to turbine blades and others elements of turbine engines because of its high

creep and oxidation resistance

Table 1 Chemical composition of MARndashM247 superalloy (wt )

Cr Ni Co Mo W Ta Ti Al Fe C Others

825 bal 100 07 100 30 10 45 lt 05 015 0015 B 005 Zr 15 Hf

3 Experimental

The presence of carbides in polycrystalline MARndashM247 superalloy was confirmed by X-ray

diffraction (XRD) The X-ray analysis carried out on the powder of the superalloy indicated the

presence not only MC (TiC WC TaC) but also small amount of M23C6 (Cr23C6) carbides [20]

The results of Xndashray diffraction were verified by studies on the material using an Hitachi

HD-2300A scanning transmission electron microscope (STEM) with an accelerating voltage of

200kV The carbide phases were identified using selected area electron diffraction (SAED)

Chemical composition analyses of the MC carbides conducted using energy dispersive

spectrometry (EDS) system attached to SEM developed quantitative chemical analyses of the phases

and discovered the occurrence of several variations of these carbides with various contents of carbide

forming elements

The samples of MARndashM247 superalloy for microstructural examinations were ground polished

and chemically etched The process of sample preparation with applied machine parameters for light

microscopy (LM) and scanning electron microscopy (SEM) was described in detail in [15] Selection

of etching methods of primary carbides in MARndashM247 superalloy was discussed in reference [21]

The foils for STEM were mechanically thinned to 003-005 mm and further electropolished with

a solution of 10 perchloric acid and 90 ethanol at -25degC

4 Results and discussion

Light microscope (LM) was first of all applied to the observation of carbides distributed in the

microstructure of the superalloy The observation of the polished and etched specimens by means of


2

an Olympus GX71 light microscope revealed not only carbides in the microstructure of MAR-M247

superalloy but also γrsquo phase precipitates and (γ+γrsquo) eutectic (figure 1)

a) b)

Figure 1 Microstructure of MARndashM247 superalloy LM polarized light (a) and DIC (b) The

sample etched with solution of HCl and H2O (a) and 15g CuCl2 33ml H2O 33ml HCl 33ml

C2H5OH (b)

The light microscopy was not useful for the studies of the carbides in detail hence the microstructure

was examined using an Hitachi S-4200 SEM as well as Hitachi S-3400N SEM both equipped with

energy-dispersive spectrometer EDS system of Noran

Observations by means of scanning electron microscope (SEM) obtained more information about the

morphology of MC carbides (figure 2) as well as the location of MC and M23C6 carbides (figures 3-4)

The back-scattered electron (BSE) images made it possible to better differentiate grey level

differences between the carbides and the matrix The bright carbides on the images registered using

BSE techniques are highly visible against the dark background of the matrix on the unetched sample

(figures 4a-d) as well as on the etched sample (figures 4ef)

On the basis of the SEM studies that were carried out it has been determined that the

microstructure of the examined material consists of γ solid-solution matrix γrsquo phase precipitates with

a cubic shape the (γ+γrsquo) eutectic and MC and M23C6 carbides

The carbides are located at the grain boundaries (figure 4a) and in the interdendritic regions

(figures 4acd) Numerous examples of MC carbides occurred within the (γ+γrsquo) eutectic (figures 3be)

It can be seen that the carbide morphology varied from coarse script-like (figure 4d) fine script-like

(figure 4b) to isolated blocky (figures 2d 4c) or discontinuous particles (figure 4b) Most of the MC

carbides have a blocky morphology and are located at the grain boundaries as well as in the

interdendritic regions The predominant morphology of the carbides is so-called ldquoChinese scriptrdquo with

long arms extending to the grain boundaries and primary γrsquo islands

Chromium-rich M23C6 carbides occur at the grain boundaries (figure 3d) or outer edges of the

primary γrsquo island (figures 3c 3f)

The analysis results of the MC carbides in various morphology by EDS are listed in table 2

A compositional fluctuation exists among the MC carbides in the examined superalloy specimens

(table 2)

The chemical composition analyses showed that MC carbides in MAR-M247 were complex

composition with various contents of carbide forming elements The presence of nine (not three as

described in [22]) types of primary carbides with various contents of carbide forming elements

(TaWTiHf)C ndash figure 5a (TaWHfTi) ndash figure 5b (TaHfTi)C ndash figure 5c (HfTi)C ndash figure 5d

(TaHfTi)C ndash figure 5e (HfTi)C ndash figure 5f (TaTi)C ndash figure 5g (TaHfTiW)C ndash figure 5h and


3

(HfZrTi)C containing a sulfide in the core ndash figure 5i was confirmed In the most cases the MC

carbides contained hafnium

EDS analyses of the script-like carbides revealed that the script arms and cores contained Ti Ta Hf

W and a small amount of Cr The heads of the MC carbide script structures contained larger amounts

of Hf than the cores and arms Very often MC arrow-shaped carbides were rich in Hf (figure 5c and

table 2) The blocky MC carbides contained significantly higher Hf content than the needle-shaped

carbides (figure 5bd and table 2)

The complex chemical composition of the carbides was confirmed using SEM mapping ndash figure 6

a) b)

c) d)

Figure 2 Comparison of carbidesrsquo morphology in MARndashM247 superalloy microstructure

SEM SE images The sample unetched

In figures 6-9 selected TEM micrographs with selected area electron diffraction (SAED) patterns are

presented

On the basis of the observations performed one can state that primary MC carbides occur in

MAR-M247 nickel-based superalloy as isolated particles as well as in clusters (figure 7)

Occasionally regular-shaped M23C6 carbide were present inside an MC carbide (figure 8) In many

cases M23C6 carbides occurred around MC carbides creating something looking like ldquolacerdquo (figure 9)


4

a) b)

c) d)

e) f)

Figure 3 Carbides in MARndashM247 superalloy microstructure SEM SE images The sample

was etched with a H3PO4 solution (a-d) and with 50 ml of C3H6O3 (lactic acid) 30 ml of HNO3

2 ml H2O (ef)


5

a) b)

c) d)

e) f)

Figure 4 Carbides in MARndashM247 superalloy microstructure SEM BSE images The sample was

unetched (a-d) and etched with H3PO4 solution (ef)

Many fine M23C6 carbides were very often located on the γγrsquo interface (figure 10 with carbides

between γrsquo participates) as well as at the MCγ interface


6

Figure 5 Comparison of MC carbide morphology in the MAR-M247 superalloy SEM images

Table 2 Comparison of chemical composition of the MC carbides from figure 5 EDS

Carbide

Element content

Ti Cr Co Ni Hf Ta W Zr

m a m a m a m a m a m a m a M a

A1 65 187 07 18 080 19 44 104 374 289 399 305 103 78

A2 80 199 13 29 150 30 112 227 222 149 444 292 114 74

B 39 119 07 19 10 27 45 110 542 441 261 209 96 75

C 14 50 914 880 72 7

D 49 16 87 213 864 771

E 123 345 365 275 512 38

F 69 16 130 17 801 814

G 148 335 124 229 728 436

H 273 120 57 27 4 2 91 98 221 148 211 517 107 7

I 12 39 46 115 864 719 78 127

where m ndash wt a ndash at


7

Figure 6 Two MC carbides HfC and (Hf Ta Ti)C and chromium-rich fine M23C6 carbides

in MAR-M247 superalloy SEM SE image and elemental mapping


8

Figure 7 A cluster of MC carbides in MAR-M247

nickel-based superalloy

STEM image and SAED pattern

Figure 8 An M23C6 carbide inside an MC carbide in

MAR-M247 nickel-based superalloy


Figure 9 The ldquolacerdquo of M23C6 carbides around the

MC carbide in MAR-M247 nickel-based superalloy

STEM image and SAED pattern (slightly visible

reflections close to each other marked with arrows

indicate M23C6 carbide)


9

Figure 10 M23C6 carbides between γrsquo precipitates in

MAR-M247 nickel-based superalloy STEM image

and SAED pattern

4 Conclusion

The microstructure of MAR-M247 nickel-based superalloy is strengthened by γrsquo precipitates and

carbides The studies performed confirmed the presence of primary MC and secondary M23C6 carbides

in an as-cast MAR-M247 superalloy after thermal cycling

The carbides are located at the grain boundaries and in the interdendritic regions Numerous MC

carbides occur within or at the periphery of the (γ+γrsquo) eutectic The morphology of MC and M23C6

carbides is very complex MC carbides are present as discrete blocky precipitates of a diversified

shape and size as well as in clusters The predominant morphology of those carbides visible at low

magnifications (approximately up to 1500 times) are ldquoChinese script-likerdquo structures at interdendritic

regions

The MC carbides in the superalloy examined are characterized by a complex composition with

various contents of carbide forming elements The EDS results prove that several distinct types of MC

carbides exist in the investigated MAR-M247 superalloy

The secondary M23C6 carbides are very fine and exist at the grain boundaries and the outer edges of

the primary γrsquo islands They often formed a characteristic bdquolacerdquo around MC carbides and were

identified in the vicinity of MC carbides and even inside them M23C6 carbides also separate from

solution at γγrsquo interfaces or at MCγ interfaces as well as at the boundaries of matrix grains

The reaction of MC carbide degeneration (MC + γ rarr M23C6 + γrsquo) is well known It takes place

during thermal exposure of the nickel-based superalloy It is a diffusion-controlled process The

products of the degeneration are M23C6 and γrsquo on the MCγ interface This study confirmed that the

process occurs

Acknowledgements

Financial support of Structural Funds in the Operational Program - Innovative Economy (IE OP)

financed from the European Regional Development Fund - Project No POIG010102-00-01508 is

gratefully acknowledged

References

[1] Donachie M J and Donachie S J 2002 Superalloys - A Technical Guide (ASM International

Materials Park Ohio USA)


10

[2] Sims C T Norman S S and Hagel W C 1987 Superalloys II (John Wiley amp Sons Inc New York

USA)

[3] Mitchell A Cockcroft S L Schvezov C E Loquet J N Fernihough J and Schmalz A J 1996 High

Temperature Materials and Processes 15 No 12 27

[4] Liu LR Jin T Zhao NR Sun XF Guan HR Hu ZQ 2003 Mater Sci Eng A361 191

[5] He L Z Zheng Q Sun X F Guan H R Hu Z Q Tieu A K Lu C and Zhu H T 2005 Mater Sci

Eng A397 297

[6] Yang J Zheng Q Sun X Guan H and Hu Z 2006 Mater Sci Eng A429 341

[7] Chen J Lee J H Jo C Y Choe S J and Lee Y T 1998 Mater Sci Eng A247 113

[8] Chen Q Z Jones C N and Knowles D M 2002 Scripta Mater 47 669

[9] He L Z Zheng Q Sun X Hou G Guan H and Hu Z 2005 J Mater Sci 40 2959

[10] Yang J Zheng Q Sun X Guan H and Hu Z 2006 J Mater Sci 41 6476

[11] Bor H Y Chao C G and Ma C Y 1998 Scripta Mater 382 329

[12] Kotval P S Venables J D and Calder R W 1972 Role of hafnium in modifying the microstructure

of cast nickel-base superalloys Metall Mater Trans B 32 457

[13] Wawro S W 1982 MC carbide structures in Mar-M247 NASA Report 167892 (Lewis Research

Center USA)

[14] Saam A and Radavich J F 1982 Microstructural Sci 10 393 [15] Szczotok A 2011 IOP Conference Series Materials Science and Engineering 22 012007

[16] Belan J 2011 Mater Eng 18 121

[17] Baldan A 1991 J Mater Sci 26 3879

[18] Yunrong Z and Yulin C 1980 Phase transformations in hafnium-bearing cast nickel-base

superalloys Proceedings of Fourth International Symposium ldquoSuperalloysrdquo Champion

Pennsylvania 465

[19] Wei C N Bor H Y Ma C Y and Lee T S 2003 Mater Chem Phys 80 89

[20] Szczotok A 2007 Inżynieria Materiałowa 3-4 468

[21] Szczotok A Szala J Cwajna J and Hetmańczyk M 2006 Mater Charact 56 348

[22] Lund C and Radavich J F 1980 Effects of refractory additions on the structure and mechanical

properties of a Hf containing nickel base superalloy Proceedings of Fourth International

Symposium ldquoSuperalloysrdquo Champion Pennsylvania 85


11

Microstructural studies of carbides in MAR-M247 nickel-

based superalloy

A Szczotok K Rodak

Silesian Technical University Faculty of Materials Engineering and Metallurgy

Krasinskiego 8 40-019 Katowice Poland

E-mail agnieszkaszczotokpolslpl

Abstract Carbides play an important role in the strengthening of microstructures of

nickel-based superalloys Grain boundary carbides prevent or retard grain-boundary sliding and

make the grain boundary stronger Carbides can also tie up certain elements that would

otherwise promote phase instability during service Various types of carbides are possible in

the microstructure of nickel-based superalloys depending on the superalloy composition and

processing In this paper scanning electron and scanning transmission electron microscopy

studies of carbides occurring in the microstructure of polycrystalline MAR-M247 nickel-based

superalloy were carried out In the present work MC and M23C6 carbides in the MAR-M247

microstructure were examined

1 Introduction

Addition of carbon in amounts from 005 to 02 and carbide forming elements enables precipitation

of mainly M23C6 MC and M6C types carbides in the superalloys These carbide phases are not stable

Under the influence of service temperature and time they may undergo transformations changing their

kind size and morphology which affect the alloysrsquo properties at high temperatures [1]

The carbide phase precipitates have an important role on the mechanical properties of superalloys

[2-5] Discrete carbides precipitating at grain boundaries (GBs) can inhibit GB sliding and improve the

strength and creep resistance of the superalloy at elevated temperatures Primary as well as secondary

carbides strengthen superalloys making difficult grain boundary slip during creep and tying up

elements that could contribute to phase instability during exploitation of the alloy into stable phases

[6] Grain boundary slip is hindered by M23C6 carbides in favor of creep resistance Morphology of

these carbides has a significant effect on nickel-based superalloys properties Shape change of M23C6

carbides along grain boundaries from blocky to fine globular particles leads to increase of temporary

creep resistance and improvement of nickel-based superalloys plasticity [1]

The formation sequence composition and morphological evolution of MC carbide from slow to rapid

solidification conditions have been characterized in numerous works [7-10]

In general the morphology of MC carbides in an as-cast Ni-based superalloy mainly depends on its

composition and casting parameters because this type of carbide is formed during solidification of the

nickel-based superalloy Previous investigators have reported how to control the morphology of MC

carbides for superalloys [8 11] The MC carbides may break down to form M6C andor M23C6 carbides

during high temperature treatments so a size morphology and a type of a carbide can be changed

during heat treatment of the superalloy


Published under licence by IOP Publishing Ltd 1









is about 24 [11]








2 Material









825 bal 100 07 100 30 10 45 lt 05 015 0015 B 005 Zr 15 Hf

3 Experimental










forming elements











2



a) b)



C2H5OH (b)
























(table 2)







3









a) b)

c) d)




presented






4

a) b)

c) d)

e) f)



2 ml H2O (ef)


5

a) b)

c) d)

e) f)






6



Carbide

Element content



A1 65 187 07 18 080 19 44 104 374 289 399 305 103 78

A2 80 199 13 29 150 30 112 227 222 149 444 292 114 74

B 39 119 07 19 10 27 45 110 542 441 261 209 96 75

C 14 50 914 880 72 7

D 49 16 87 213 864 771

E 123 345 365 275 512 38

F 69 16 130 17 801 814

G 148 335 124 229 728 436

H 273 120 57 27 4 2 91 98 221 148 211 517 107 7

I 12 39 46 115 864 719 78 127



7




8













9



and SAED pattern

4 Conclusion









regions











process occurs

Acknowledgements




References




10


USA)





Eng A397 297










Center USA)






Pennsylvania 465








11









is about 24 [11]








2 Material









825 bal 100 07 100 30 10 45 lt 05 015 0015 B 005 Zr 15 Hf

3 Experimental










forming elements











2



a) b)



C2H5OH (b)
























(table 2)







3









a) b)

c) d)




presented






4

a) b)

c) d)

e) f)



2 ml H2O (ef)


5

a) b)

c) d)

e) f)






6



Carbide

Element content



A1 65 187 07 18 080 19 44 104 374 289 399 305 103 78

A2 80 199 13 29 150 30 112 227 222 149 444 292 114 74

B 39 119 07 19 10 27 45 110 542 441 261 209 96 75

C 14 50 914 880 72 7

D 49 16 87 213 864 771

E 123 345 365 275 512 38

F 69 16 130 17 801 814

G 148 335 124 229 728 436

H 273 120 57 27 4 2 91 98 221 148 211 517 107 7

I 12 39 46 115 864 719 78 127



7




8













9



and SAED pattern

4 Conclusion









regions











process occurs

Acknowledgements




References




10


USA)





Eng A397 297










Center USA)






Pennsylvania 465








11



a) b)



C2H5OH (b)
























(table 2)







3









a) b)

c) d)




presented






4

a) b)

c) d)

e) f)



2 ml H2O (ef)


5

a) b)

c) d)

e) f)






6



Carbide

Element content



A1 65 187 07 18 080 19 44 104 374 289 399 305 103 78

A2 80 199 13 29 150 30 112 227 222 149 444 292 114 74

B 39 119 07 19 10 27 45 110 542 441 261 209 96 75

C 14 50 914 880 72 7

D 49 16 87 213 864 771

E 123 345 365 275 512 38

F 69 16 130 17 801 814

G 148 335 124 229 728 436

H 273 120 57 27 4 2 91 98 221 148 211 517 107 7

I 12 39 46 115 864 719 78 127



7




8













9



and SAED pattern

4 Conclusion









regions











process occurs

Acknowledgements




References




10


USA)





Eng A397 297










Center USA)






Pennsylvania 465








11









a) b)

c) d)




presented






4

a) b)

c) d)

e) f)



2 ml H2O (ef)


5

a) b)

c) d)

e) f)






6



Carbide

Element content



A1 65 187 07 18 080 19 44 104 374 289 399 305 103 78

A2 80 199 13 29 150 30 112 227 222 149 444 292 114 74

B 39 119 07 19 10 27 45 110 542 441 261 209 96 75

C 14 50 914 880 72 7

D 49 16 87 213 864 771

E 123 345 365 275 512 38

F 69 16 130 17 801 814

G 148 335 124 229 728 436

H 273 120 57 27 4 2 91 98 221 148 211 517 107 7

I 12 39 46 115 864 719 78 127



7




8













9



and SAED pattern

4 Conclusion









regions











process occurs

Acknowledgements




References




10


USA)





Eng A397 297










Center USA)






Pennsylvania 465








11

a) b)

c) d)

e) f)



2 ml H2O (ef)


5

a) b)

c) d)

e) f)






6



Carbide

Element content



A1 65 187 07 18 080 19 44 104 374 289 399 305 103 78

A2 80 199 13 29 150 30 112 227 222 149 444 292 114 74

B 39 119 07 19 10 27 45 110 542 441 261 209 96 75

C 14 50 914 880 72 7

D 49 16 87 213 864 771

E 123 345 365 275 512 38

F 69 16 130 17 801 814

G 148 335 124 229 728 436

H 273 120 57 27 4 2 91 98 221 148 211 517 107 7

I 12 39 46 115 864 719 78 127



7




8













9



and SAED pattern

4 Conclusion









regions











process occurs

Acknowledgements




References




10


USA)





Eng A397 297










Center USA)






Pennsylvania 465








11

a) b)

c) d)

e) f)






6



Carbide

Element content



A1 65 187 07 18 080 19 44 104 374 289 399 305 103 78

A2 80 199 13 29 150 30 112 227 222 149 444 292 114 74

B 39 119 07 19 10 27 45 110 542 441 261 209 96 75

C 14 50 914 880 72 7

D 49 16 87 213 864 771

E 123 345 365 275 512 38

F 69 16 130 17 801 814

G 148 335 124 229 728 436

H 273 120 57 27 4 2 91 98 221 148 211 517 107 7

I 12 39 46 115 864 719 78 127



7




8













9



and SAED pattern

4 Conclusion









regions











process occurs

Acknowledgements




References




10


USA)





Eng A397 297










Center USA)






Pennsylvania 465








11



Carbide

Element content



A1 65 187 07 18 080 19 44 104 374 289 399 305 103 78

A2 80 199 13 29 150 30 112 227 222 149 444 292 114 74

B 39 119 07 19 10 27 45 110 542 441 261 209 96 75

C 14 50 914 880 72 7

D 49 16 87 213 864 771

E 123 345 365 275 512 38

F 69 16 130 17 801 814

G 148 335 124 229 728 436

H 273 120 57 27 4 2 91 98 221 148 211 517 107 7

I 12 39 46 115 864 719 78 127



7




8













9



and SAED pattern

4 Conclusion









regions











process occurs

Acknowledgements




References




10


USA)





Eng A397 297










Center USA)






Pennsylvania 465








11




8













9



and SAED pattern

4 Conclusion









regions











process occurs

Acknowledgements




References




10


USA)





Eng A397 297










Center USA)






Pennsylvania 465








11













9



and SAED pattern

4 Conclusion









regions











process occurs

Acknowledgements




References




10


USA)





Eng A397 297










Center USA)






Pennsylvania 465








11



and SAED pattern

4 Conclusion









regions











process occurs

Acknowledgements




References




10


USA)





Eng A397 297










Center USA)






Pennsylvania 465








11


USA)





Eng A397 297










Center USA)






Pennsylvania 465








11

Microstructural studies of carbides in MAR-M247 nickel-based

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