Uwe Glatzel

Single Crystal Nickel Based Superalloys 

for High Temperature Applications 

- Microstructure Microstructure, Properties Properties, Anisotropy - 

Uwe Glatzel 

Metals and Alloys 

University yBayreuth y 

University Bayreuth Uwe Glatzel, Metals and Alloys 

1

Content 

• motivation: history, application field 

• processing 

• microstructure, misfit 

• anisotropic properties 

(modulos (modulos, creep behavior) 

• dislocations, stress induced diffusion 

• Outlook: alloys with reduced density, platinum 

based superalloys 


2

Superalloys for Extreme 

DDemands d 

Single crystal nickel based superalloys as material for first 

rotating blades after the 

combustion chamber in aircraft flight g engines. g 

fan 

(thrust) 

compressor (titanium) 

gas temp.: 1500°C 

material: 1100°C 

20 20.000 000 rpm 

⇒ const. stress of 

about 100 MPa 

(≈ 1 car/cm2 ) 


3

Model 

JetCat P120SX 

Flight Model 

Rolls Royce RR300 

Helicopter 

Engine g Alliance 

GP 7270 

Airbus A380 

Examples Turbine Engines 

engine g 

weight 

[kg] 

engine power 

[kW] 

22 

14 1.4 

(push: 0.13 kN) 

disc revolution max. (!) () 

diameter 

[m] 

speed 

[1/min.] 

consumption 

[l/h] 

cost 

[1,000 €] 

007 0.07 123 123,000 000 ~ 23 28 2.8 

80 225 ~ 0.24 50,000 ~ 80 ? 

BMW R6 (N52) 161 190 - - 6,000 ~ 65 ~ 6 

stationary gas turbine 

SGT5-8000H, 

Irsching close Munich, 

efficiency > 40% 

combined cycle > 60% 

6,700 

444,000 

60 60,000 000 take k off ff ~ 18 18,000 000 

~ 1.00 12,000 

(push: 370 kN) 

cruise ~ 3,600 

375,000 

(c.c.: 570 MW) 

~ 4.00 3,000 

~ 85,000 heavy 

fuel oil 

(~ 100,000 m3 /h 

gas) 

~ 13,000 

~ 200,000 


4

adius r 

[m] 

Stress σ at the Foot of the Blade 

rotational blade stress 

2 

speed ω h A 

cyc length h σ Fz m⋅ω 

⋅ r ρ ⋅h 

⋅ A 

σ = = = 

[1/s] [m] [MPa] A A A 

0.035 2,050 0.01 464 

2 

⋅ω 

⋅ r 

2 ( ) 2 

= ρ ⋅ h⋅ ω ⋅ r = ρ ⋅ h⋅ 

ω ⋅ ⋅ r 

~ 0.12 833 0.03 790 cyc 2π 

0.12 833 0.03 790 

~ 050 0.50 200 008 0.08 505 

ρ≈8 g/cm 3 … material density 

F z … centrifugal force 

A … area of blade foot 

~ 2.00 50 0.25 394 ω … angular speed 

maximum, short time stresses! 


5

Blade for 

stationary 

gas turbine bi 

for power 

production 

≈ $ 40 40.000 

000 

Big Big, Single Crystal Blade 


6

η = 

max 

theor. h 

Coefficient of Efficiency 

T 

regular fuel car engine: < 37% 

car diesel engine: < 43% 

ship hi di diesel l engine i ( (up tto 900/ 900/min.): i ) < 50% 

aircraft turbine: < 40% 

stationary gasturbine: < 42% 

gas and steam generation: < 60% 

Irsching (gas and steam generation): ~ 60% 

(gas (g + steam + longg distance heating:~ g 87%) ) 

max 

− T 

T 

min 

min 

increase of Tmax increases 

coefficient of efficiency 


7

[°C] 

tempperature 

2000 

1500 

1000 

500 

Increase in Temperature due to 

Improved Construction and Material 

polycrystalline 

military 

civilian 

directional solidified 

single i l crystal t l 

gas temper perature 

material tempera perature 

improved cooling 

improved materials 

1950 1960 1970 1980 1990 2000 

year 

ceramics?? 

platinum lti 

base alloys? 

constant 

improvement 

5-10°C/year 


8

floww 

stresss 

[MPaa] 

500 

400 

Why nickel based superalloys? 

Anomalous flow stress behavior of the 

intermetallic phase Ni3Al: superalloy heat treated 

300 superalloy as cast 

200 

100 

Copley l and dKear, 

Trans. AIME 

Vol. 239 (1967), 984-992 

0 

Ni 3 Al 

nickel solid solution 

0 200 400 600 800 1000 

ttemperature t [°C] 

70 % 

100 % 

0 % 


9

History yTurbine Engines g 

(very strong connected with materials history) 

Patents on stationary turbines: 1873 first patent application Franz 

Stolze, Berlin "Feuerturbine" (� denied). 1884 Britain first stem 

turbine patent granted. Stolze's 2 nd attempt 1897 succesful (same 

year in USA). First time running in 1904 with 400°C inlet 

temperature. 

Commercially 

successful 

~1930 


10

History y Flight g Engines g 

(very strong connected with materials history) 

• ~ 1930 development of turbine engines for airplanes airplanes. 

• 1939 first succesful flight with JUMO 004 on a Me 262 fighter. 

Milit Military was not t convinced i dof f bth both airplane i l andd engine. i Bi Big 

problems with life time of turbine blades (only ~ 10 h). 

First material: TINIDUR Fe Ni30 Cr14 Cr14, then switched to 

CROMADUR Fe Cr12 Mn 18 (due to Ni shortage) 

JUMO 004 

Me 262 replica 


11

Recent History Materials 

≈ 1980: Inconel 738 (polycrystalline) => 738 LC (single crystal) 

50-60vol.% γ' phase, 3wt.% W, 0% Re 

SRR 99, CMSX-6 (first generation single crystal) 

60-70% γ', 9% W, 0% Re 

≈ 1990 1990: CMSX CMSX-4 4( (secondd generation ti SX) 

> 70 % γ', 6% W, 3% Re 

≈ 1995: CMSX-10 CMSX 10 (third generation SX) 

> 70 % γ', 6% W, 6% Re 

Costly and time intensive heat treatment: 

3-stage homogenization, controlled rapid cooling 

2-stage aging 


12

Content 







• Outlook (alloys with reduced density, platinum based 

superalloys) p y ) 


13

R = ΔT/Δx 

Single Crystal Growing 

v = Δx/Δt 

alternative: seeding technique 

[001] 

crystal 

direction 

R⋅v = ΔT/Δt / 

determines the dendrite 

spacing i 


14

Heat Treatment 

example: CMSX-4 standard heat treatment 

homogenization: 

1h@1280°C 1 h @ 1280 C, 2 h @ 1290 1290°CC, 6 h @ 1300 1300°CC 

cooling rate 150-400°C/min. 

aging 

6 h @ 1140 1140°CC für 6 h, 870 870°CC für 16 h 

if possible, possible combined with coating treatment 


15

Content 










16

Microstructure 

ttwo-phase, h single i l crystal: t l 

face face-centred-cubic 

centred cubic 

matrix 

(nickel solid solution) 

Ni 3Al => fcc, but superlattice 

ordering, d i L1 2 or γ' 'Ph Phase di dislocation l ti free 

f 


17

Ni Ni3Al 3Al ⇔ nickel solid solution 

nickel atoms in face centre 

aluminium atoms on 

cube corners 

d Ni3Al = 358,0 pm d nickel solid sol. = 358,7 pm 

in nickel solid solution � statistical distribution of atoms 


18

Optimal Precipitation Hardening 

• round dparticles i l 

(better than needle-shaped) 

• hi high h volume l fraction f i 

• finely dispersed 

• small ll particles ti l ( ) 

• hard precipitates, 

soft ft matrix t i 

in text books no 

information given on 

optimum misfit 

500 nm 


19

Constrained ↔ Unconstrained 

Misfit 

Small difference in lattice parameter, Δd/d ≈ - (1 – 3)·10 -3 

resulting in a coherent interface and internal stresses: 

Matrix 

isotropic misfit 

γ' Phase 

Δ d 

σ = E ≈100 

− 300 MPa 

d 

Matrix 

γ' Phase 

misfit high dependent compression stresses of planes in 

taken k matrix for f parallel Bragg B to reflection 

interface 

fl i 


20

Two-Phase but 100% Coherent 

=> Internal Stresses 


21

Stress Distribution 

stress 

σxx [MPa] 

two views of 1/8 of the γ' γ cube with surrounding g 

matrix 


22

in γ' phase 

compression 

tension 

Stress Distribution 

Schematical 

in matrix 


23

ddendrite d i spacing i 

≈ 1/4 mm 

single crystal, 

bt but no hgomogeneous 

h 

distribution of tungsten 

and rhenium 

"Macrostructure" 

Macrostructure 

[010] 

[001] 

⇒ therefore local variation of misfit 


24

Variation of Misfit due to 

Dendritic Segregation 

[10 -3 ] 

• negative misfit in dendrite 

• close to zero in interdendritic region 

Völkl, Glatzel, Feller-Kniepmeier; Acta mat. 46 (1998) 4395 

1 

0 

-1 

-22 

-3 

-4 

-5 

Fehlpassung gemessen mit CBED 

Neutronenstreuung 

Interdendrit Dendrit Interdendrit 


25

interdendritic region 

Spannnung 

[MPPa] 

-50 

-100 

-150 

-200 

-250 

-300 300 

Local Stress Variation 

dendrite 

200 400 600 800 

-2.5 

-5 

-7.5 

-10 10 

-12.5 

up to 300 MPa compression stress 

-15 

iin matrix t i channels h l in i dendrite d d it 

-17.5 

spacing i ≈ 250 μm 

5 10 15 20 

spacing ≈ 0,5 μm 


26

Content 










27

Elastic Anisotropy together 

with ihMi Misfit: fi 

�� Explanation for cuboidal γ' precipitates, 

with {100} phase boundary planes 

�� thereby very high volume fractions 

achievable 


28

00> [GPa] 

E

Creep Deformation 


30

High Temperature 

Deformation up to 1400°C 

temperature 

and load are 

kept ept co constant sta t 


31

l 0 

Orientation Dependence 

Single crystal with load axis 

parallel to [001] 

constant load of 500 MPa 

(T = 850°C) 

"horizontal" / "vertical" 

matrix channels 

at 850°C 

10-6 

Strrain 

Rate [11/s] 

10 -7 

10 -8 

→ [001] orientation shows best 

creep performance 

A 2 

A 1 

C 1 

B 2 

B 1 

+ 

+ 

+Fracture 

M 

CMSX-4 

1123K, 500MPa 

0 1 2 3 

Strain [%] 

C1 

University Bayreuth 32 

Uwe Glatzel, Metals and Alloys 

[111] 

M 

A 2 

B2 B 2 

A 1 

[001] B 1 [011]

te [s ] -1 strain 

rat ] 

Orientation Dependence 

C 

at 980°C 

A A 

strain 

C 

anisotropy has less 

influence at higher 

temperatures 


33

Changes in Morphology 

980°C, 350 MPa, 28 h 

[100] 

rafts with planes normal to the 

external [001] load axis 

σ σ 

[001] [110] 

[010] 

[100] 

bars with long axis 

parallel to 


34 

[110]

[001] crystal orientation: 

• fastest growing direction + 

• elastic soft is good for thermal fatigue + 

• elastic soft and misfit leads to {001} phase 

boundaries (� cuboidal γ' particles) + 

• direction of best creep properties + 


35

Content 










36

Dislocation configuration 

during primary creep 

Ph.D. thesis 

Th. Link, 

TU-Berlin 

(1988) 

Movement of dislocations 

up to 0.5% plastic 

deformation mainly in 

matrix channels. 


37

FEM calculation of stress 

di distribution ib i ( (pure elastic) l i ) 

No external load 

� high g compression p stresses in 

matrix channels parallel to the 

phase boundaries 

σ 

compression 

tension 

With an external load (500 MPa) 

� high g stress levels in horizontal 

channels; low stress levels in 

vertical channels 

pure elastic at time t = 0 


38

tension 

FEM calculations of stress distribution 

after creep p (plastic (p deformation) ) 

(Matrix according to Norton creep, γ' phase yields plastisch) 

hydrostatic tension p ≈σ ext. 

dislocations networks: 

horizontaler channel: 

High density of edge 

dislocations with additional 

hlf half plane l within ihiγ' ' phase h 

σext. vertical channel: 

network of LH- and RH- 

screw dislocations, 

1/3 density 


39

TEM Dislocation Structure: 

cross section, ti ε = 21% 2.1 % 

external load normal to view plane 

50 disl. per cube � ρ≈20⋅10 13 m -2 

look onto horizontal matrix 

channels, vertical channels edge-on. 

longitudinal section 

ε = 1 % 

10 disl. per cube � ρ ≈ 4⋅1013 m-2 p ρ 

University Bayreuth 

load axis 

40 

Uwe Glatzel, Metals and Alloys

Stress Induced Diffusion 

(EDX-TEM) 

Large atoms diffuse from vertical to 

horizontal channel. 

horizontal channel 

tungsten 

c = 1. 

2⋅ 

σ ext ≈ 500 MPa 

ext. 

Schmidt and Feller-Kniepmeier, 1993 (SRR99, 760°C) 

c 

vertical channel 

tungsten 


41

Summary: Different Strengthening 

MMechanisms h i in i Ni-Base Ni B SSuperalloys ll 

• It Internal lb back kstress: t σ i = α ⋅ G ⋅ b b⋅ 

~ 250 MPa ≈ σexternal • Orowan stress: 

~ 500 MPa (reduced by coarsening) 

• Solid solution strengthening (e.g. by Re): 

~110MPa(short range ~1/r2 ~ 110 MPa (short range ~ 1/r ) 

σ 

ρ 

Orowan 

σ 

G ⋅b 

≈ 

L 

i 

solid solution 

• Coherent γ' precipitates: σ coherency ≈ δ ⋅ E 

~ -200 MPa (compression, reduced by semi-coherency) 

≈ 

Ω − Ω 

Ω 

i ci With α =1, G = 100 GPa ≈ E, b = 250 pm, ρ = 1014 m-2 , , p , ρ , L = 50 nm, , c Re = 1 at.%, , 

, δ = -2⋅10-3 Ω 

− ΩNi 

Re = 

Ω 

Ni 

0. 

11 


42 

E

Summary: 

changes h occuring i ddurig i creep 

dislocation networks in 

phase boundaries 

(plastic deformation 

according to local 

stress distribution) 

=> stress induced 

diffusion 

FEM 

+ 

TEM 

W Re Re W Re 

TEM 

+ 

EDX 

γ' 

W 

Re 

γ' 

W 

σ ext 

TEM + 

FEM 

=> high hydrostatic stress 

level in horizontal channel 

+ 

change in lattice 

parameter (misfit). γ' 

Change g and 

reduction of stress 

level. 

neutron diffr. 

additionally: compostion variation dendrite – interdendritic region 

and morphology changes 

University Bayreuth 43 

Uwe Glatzel, Metals and Alloys 

-

Content 








superalloys) 


44

Outlook 

• International patent (Glatzel, Mack, Wöllmer, Wortmann): 

Rd Reduce W and dR Re content t t�� reduced d dddensity, it improved i d 

phase stability, larger temperature window for solution heat 

ttreatment, t t cheaper h �� LEK 94. 94 

Within GP 7000 engine for Airbus A 380. 

• DFG-Project "Platinbasissuperlegierungen": 

Pt-Al-Cr-Ni (+ Ta, + Ti) alloys can copy successful system of nickel 

based superalloys (coherent L12 ordered, cuboidal γ' particles with 

hi high h volume l fraction f ti embedded b dd d in i fcc-matrix) 

f ti ) 


45

stress [MPa] [ 

500 

230 

120 

24 K 

ΔT = 10 K 

LEK 94 

10 K 

CMSX-6 [Wortmann 88] 8.0 g/cm 3 

CMSX-4 [Erickson 94] 8.7 g/cm 3 

CMSX-4 [Frasier 90] 8.7 g/cm 3 

LEK-2 8.5 g/cm 3 

g 

LEK-4 8.2 g/cm 3 

LEK-5 8.2 g/cm 3 

LEK-3 8.1 g/cm 3 

LEK-6 83g/cm 3 

LEK-6 8.3 g/cm 

LEK-1C 8.4 g/cm 3 

LEK-1B 8.3 g/cm 3 

LEK-1A 8.2 g/cm 3 

29 K 

25 26 27 28 29 30 31 32 

Larsen-Miller-Parameter 

Larsen Miller Parameter 

P = (T+273) [20+log tB ] 10 -3 

not corrected with 

density! y 

Patente: D, Europa, USA, Kanada, Japan 


46

PPt 77Al Al14Cr C 6Ni Ni6 

12h @1500°C + 

120h @1000°C 

CMSX-4, 

same 

magnification 

Microstructure 

Platinum Based Superalloy 

Hüller et al., Met.Mat.Trans. A, 36A (2005), 681 


47

Misfit 

Platinum Based Superalloys 

Pt84Al 84 11Cr 11 3Ni 3 2 

Pt 80Al 11Cr 3Ni 6 

Pt 77Al 10Cr 3Ni 10 


48

Stress 

1000 

100 

Creep Properties 

Platinum Based Superalloys 

CMSX-4 (single crystal !) 

Maximum Stress in 

Compression with 

-5 -1 

St Strain i Rate R t 10 5 s 1 

γ' precipitate dissolution 

in Ni-base alloys 

γ' precipitate dissolution 

in Pt-base alloys 

Pt82Al7Cr6+Ta5 

Pt82Al7C Pt82Al7Cr6+Ti5 6+Ti5 

Pt77Al12Cr6+Ni5 

Pt77Al12Cr6+Fe5 

Pt77Al12Cr6+Co5 

10 

700 800 900 1000 1100 1200 1300 1400 

Temperature [°C] 


49


50

Uwe Glatzel

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