Computational Genomic Design

of Ni & Co Alloys

Jiadong Gong, Ph.D.

Senior Engineer

QuesTek Innovations LLC

SRG

March 24, 2017

p. 2

Jiadong Gong

SRG 2017

QuesTek’s ICME approach

• Systems-based design approach utilizing computational tools to model key

process-structure and structure-property linkages

• Replacing the legacy trial-and-error approaches with parametric materials design

Faster, cheaper, targeted material performance

Modeling at all length-scales relevant to

materials design and processing

Treat material as a system, linking process-

structure-properties to meet defined

performance goals

p. 3

Jiadong Gong

SRG 2017

SX Ni Superalloy for industrial gas turbines

• DOE SBIR Phase I, Phase II, and Phase IIA award

• SX castings – High Temperature Performance– Desirable for better creep resistance – no grain boundaries

• IGT blade castings are large > 8 inches– Slower solidification / cooling rates exacerbate processing issues

• Primary casting (processing) constraints:– Freckle formation

– High angle boundaries (HAB) and low-angle boundaries (LAB)

– Hot-tearing

– Shrinkage porosity

• 3rd generation blade alloys are especially difficult to cast

as SX due to their high refractory content– Increased tendency for hot tearing

– Increased tendency for freckle formation

QuesTek’s approach: ICME-based design of a new processable, high-performance single

crystal alloy for IGT applications

p. 4

Jiadong Gong

SRG 2017

List of benchmark alloys – SX performance

ID Re Al Co Cr Hf Mo Ta Ti W other

PWA1480 - 5 5 10 - - 12 1.5 4

PWA1483 - 3.6 9 12.2 - 1.9 5 4.1 3.8 0.07C

GTD444 - 4.2 7.5 9.8 0.15 1.5 4.8 3.5 6 0.08C

CMSX7 - 5.7 10 6 0.2 0.6 9 0.8 9

CMSX8 1.5 5.7 10 5.4 0.2 0.6 8 0.7 8

PWA1484 3 5.6 10 5 0.1 2 9 - 6

CMSX4 3 5.6 9 6.5 0.1 0.6 6.5 1 6

Rene N5 3 6.2 7.5 7 0.15 1.5 6.5 - 5 0.01Y

CMSX10 6 5.7 3 2 0.03 0.4 8 0.2 5 0.1Nb

TMS238 6.4 5.9 6.5 4.6 0.1 1.1 7.6 - 4 5.0Ru

QuesTek’s Phase I design (“QT-SX”) contained these

same elemental constituents, but with 1% Re

Re-free

alloys

Recently-

developed

2nd Gen alloys

High-Re alloys

p. 5

Jiadong Gong

SRG 2017

Systems design chart for SX castings

p. 6

Jiadong Gong

SRG 2017

Modeling of liquid density during solidification

7.615

7.620

7.625

7.630

7.635

7.640

7.645

7.650

1,320 1,330 1,340 1,350 1,360 1,370 1,380 1,390 1,400 1,410 1,420

ReneN5 Liquid density vs. T

40%

20%

liquid

den

sity

, g/c

m3

Temperature, °C

liquidus

Actual modeling

output is a

combined use of

various databases

and software

Freckle-resistance is related to the modeling of the liquid density during

solidification base on a critical Rayleigh number:

p. 7

Jiadong Gong

SRG 2017

Modeling freckling behavior in N5 and QT-SX castings

Target this range (>B, <A)

p. 8

Jiadong Gong

SRG 2017

QTSX (1% Re)

CMSX8 (1.5% Re)

Thermodynamic and kinetics calculations on key

properties

• phase fraction, key temperatures

• coarsening rate

p. 9

Jiadong Gong

SRG 2017

0

0.005

0.01

0.015

0.02

0.025

0.03

Liquid density difference at 20% solidification

1%

Re

0.00E+00

2.00E-20

4.00E-20

6.00E-20

8.00E-20

1.00E-19

1.20E-19

1.40E-19

Coarsening Rate Constant for different alloys

Coarsening rate and liquid density difference

comparisons (lower is better)

Comparable coarsening rate

to CMSX-8 (1.5% Re) alloy

Reduced buoyancy

differences (less than

non-Re CMSX-7)

0%

Re

0%

Re

0%

Re

0%

Re

3%

Re

3%

Re

3%

Re

3%

Re

1.5%

Re

1.5%

Re

3%

Re

3%

Re

0%

Re

0%

Re

0%

Re

0%

Re

1%

Re

p. 10

Jiadong Gong

SRG 2017

2nd round of casting results

Rene N5

QTSX

QTSX

Solidification Rate

Rene N5Mold Geometry

p. 11

Jiadong Gong

SRG 2017

2nd round of casting results

p. 12

Jiadong Gong

SRG 2017

Microstructure after double-step aging

Characterization and microstructure analysis confirm the achievement of the design goal of γ’ phase fraction and lattice misf it

(no evidence of TCP phases were found during all heat treatments)

room temperature

lattice misfit

validated at -0.1%

p. 13

Jiadong Gong

SRG 2017

γ'

γ

γ'

γ'γ'

Atom-probe (LEAP) analysis of the QT-SX nanostructure

Ion, at.% Cr % Ni % Co % Al % Hf % Mo % Re % Ta % Ti % W %

LEAP1 1.74 66.76 6.63 17.28 0.05 0.61 0.10 3.43 0.38 2.84

LEAP2 1.92 70.34 6.64 16.97 0.08 0.85 0.07 0.72 0.42 1.79

Prediction 2.1 69.0 6.0 16.9 0.05 0.23 <0.01 4.0 0.19 1.6

γ'

γ

γ'

Excellent agreement with

predicted compositions

(γ’ comparisons below)

LEAP 1

LEAP 2

p. 14

Jiadong Gong

SRG 2017

Temperature Stress Approx Life LMP (C=20)

C F Mpa Ksi hr

850 1562 461 66.9 1000 25.8

850 1562 375 54.3 4500 26.6

950 1742 205 29.7 1000 28.1

950 1742 160 23.2 4500 28.9

950 1742 160 23.2 4500 28.9

1050 1922 124 18.0 300

1050 1922 115 16.7 1000 30.4

1050 1922 90 13.1 4500 31.3

TemperatureR Ratio

Strain

RangeC F

750 1382 -1 1.8

750 1382 -1 1.5

750 1382 -1 1.5

750 1382 -1 1.3

750 1382 -1 1.3

950 1742 -1 1.5

950 1742 -1 1

950 1742 -1 0.9

950 1742 -1 0.9

950 1742 -1 0.75

950 1742 -1 0.65

LCF

Stress Rupture (*Creep)Temperature

C F

22 71.6

22 71.6

600 1112

760 1400

800 1562

900 1652

1000 1832

1100 2012

1200 2192

Tensile

Density

Thermal Diffusivity (22 – 1200C)

Thermal Conductivity (22 – 1200C)

Specific Heat (22 – 1200C)

CTE (22 – 1200C)

Elastic Modulus

Shear Modulus

Poisson’s Ratio

Physical PropertiesSulfidation Testing

• Burner rig testing at

Cranfield.

• QTSX vs. Rene N5

• Preparing samples and

awaiting SOW from

Siemens to start testing

Oxidation Testing

• Small cubes exposed to air

at elevated temperature

(1000 and 1150C)

• Small cubes exposed to air

in cyclic environment at

Siemens

Initial property data development plan

p. 15

Jiadong Gong

SRG 2017

Testing results – physical properties

Property Result Secondary Data

Density 0.316 lb/in3 8.735 g/cm3

0.320 lb/in3 8.861 g/cm3

0.321 lb/in3 8.890 g/cm3

0.320 lb/in3 8.845 g/cm3

Poisson’s Ratio 0.3804 18.58 Msi 128.1 GPa

0.3556 18.86 Msi 130.0 GPa

Young’s Modulus 18.8 Msi 129.6 GPa

19.1 Msi 131.7 GPa

Shear Modulus 19.27 Msi 132.9 GPa

18.75 Msi 129.3 GPa

p. 16

Jiadong Gong

SRG 2017

Testing results – fatigue

• Still in-progress:

– 1382°F

• Strain range:

– 1.3, 1.3, 1.5

– 1742°F

• Strain range:

– 0.65, 0.75, 1.5

p. 17

Jiadong Gong

SRG 2017

Stress rupture test results (ASTM E139)

Comparison to Select Incumbent SX alloys*

*Baseline data taken from respective patent filings, literature

1%

Re

3%

Re

1.5%

Re

3%

Re

3%

Re

0%

Re

0%

Re

QTSX: Temperatures evaluated from 870

to 1150°C with times up to 1700 hrs

p. 18

Jiadong Gong

SRG 2017

Commercialization

• QTSX license discussions ongoing with OEM

• QTSX potential evaluation program in 2017

p. 19

Jiadong Gong

SRG 2017

A new Co: as a Cu-Be Replacement

A high-strength, wear-resistant material alternative to Cu-Be is sought for

highly loaded, unlubricated aerospace bushing applications to avoid

health-hazards associated with Be.

• Key property goals are WEAR resistance and STRENGTH• Low-friction bushing applications

• Achieve strength in large product sizes without cold work (Quench suppressibility)

Objective

Design and develop an environmentally safe drop-in alternative alloy as a

substitution for highly loaded bushing applications

Vertical Tail Hinge Assembly

Wing Lug Attach

Main Landing Gear

p. 20

Jiadong Gong

SRG 2017

CoCr alloy with precipitation strengthening

• High Cr content – Wear/Corrosion

• Minimize the hardness and ease of machining in

annealed state– Minimize interstitial elements (C, N)

– Most machining before final solution heat treatment

• Design for a precipitation-strengthening dispersion

– Similar microstructures recently demonstrated for

CoAlW

– Solution-treatable following (rough) machining in

annealed state

– Coherent phase is ideal: (L12 or γ’) – Co3Ti

– Efficient precipitation during tempering > ~700-900°C

– Ensure good lattice parameter matching between the

FCC matrix and ordered FCC (L12) particles

• Design for good solidification and hot-working

• Design for an efficient grain pinning dispersion

– TiC can be effective at low phase fraction

J. Sato et al., vol. 312, Science, 2006

p. 21

Jiadong Gong

SRG 2017

Systems Design Chart

VIM/VAR

melting

Homogenization

Hot working

>4” dia.

Solution

treatment

Machining

Tempering

Processing Structure

Solidification

structure

- Inclusions

- Eutectic

Grain Structure

- Grain size

- GB chemistry

- pinning particles

- Avoid cellular

reaction

Nanostructure

- Low-misfit L12

- Size & fraction

- Avoid embrittling

phases

Matrix

- FCC (avoid HCP

transformation)

- Low SFE

- Solid solution

strengthening

Properties

Non-toxic

Strength

-120 to 180 ksi

compressive YS

- CW not required

for strength

Wear

- Low CoF

- Galling/fretting

resistance

Toughness

-Highly ductile after

solution treat

- High toughness

fully hardened

Corrosion

Resistant

Environmentally

Friendly

Bearing Strength

Wear Resistance

Damage Tolerant

Formable

Performance

Corrosion

Resistant

p. 22

Jiadong Gong

SRG 2017

Co System Thermodynamics with L12

• Develop thermodynamic database

– Search composition space for achieve targeted microstructure

– Co-Cr-Ti-W-Fe-Ni-V-C multicomponent thermodynamic database assessment complete

• Design for FCC – L12 lattice parameter matching for stable, coherent dispersion

– Avoid cellular growth reactions at grain boundary (Cr, Fe & V to reduce misfit)

– Stabilize FCC (vs. HCP) at tempering temperature (Fe, Ni)

Co

Al

W Co

Ti

Cr

Isothermal

section at 1173K

γ’

γ’

p. 23

Jiadong Gong

SRG 2017

Conceptual Design Approach

Equilibrium step diagram

Calculation using QuesTek Co database

Calculated contour plots of the γ’ volume

fraction and lattice misfit as a function of

composition

Key design challenges are to: 1) avoid HCP; 2) avoid eta during tempering; 3) avoid Co4Cr2Ti phase

while maintaining high Cr

p. 24

Jiadong Gong

SRG 2017

γ’=16%

Design Iteration:

Optimize Strength and Processability

γ’=22%

1st Generation 3rd Generation

γ γ

LL

Solutionizing window

Tempered condition for 1st Generation characterization(aged at 780C/24 hours – Hardness of 34.8 HRC)

Design of Alloy by CALPHAD

• Maximizing 𝛾′ fraction for strength

• Considering processing (e.g.

solutionizing window)

Optimizing Temper Treatment

• Identify time to peak strength for

reduced processing time

p. 25

Jiadong Gong

SRG 2017

Validation of Design with LEAP

• Validation of alloy nanostructure using

atom probe tomography after tempering

at ~780 °C:

– FCC (Co-rich) matrix and γ’ (L12 crystal

structure, Co3Ti-type) strengthening

nano-precipitates

Side viewTop view

p. 26

Jiadong Gong

SRG 2017

Scale-up Production and Process Optimization

Tempered condition for 1st Generation characterization(aged at 780C/24 hours – Hardness of 34.8 HRC)

410 HV

Alloy production (500 lb. VIM/VAR scale)

Heat treatment optimization is

performed by isothermal holding at

different aging temperatures for

various times (note long times).

The peak hardness condition was

identified as 780°C for 72 hours, then

optimized to within 48 hours

T = 780°C

After ForgingDiameter~6’’

p. 27

Jiadong Gong

SRG 2017

Sub-scale bushing tests showed

• Sub-scale bushing test showed

equivalent wear resistance to Toughmet

• Equivalent galling resistance to Cu-Be

(no galling up to yielding)

• <0.9% wear resistance was program

goal

Dimensional Wear

p. 28

Jiadong Gong

SRG 2017

QT Co Property Comparison

Typical

Tensile

Properties

CuBe

C17200

(HT04)

Toughmet 3

(Cu-Ni-Sn)

ACUBE100

(Co-Cr-Mo)

QuesTalloy Co

(Co-Cr-Fe-Ti-

Ni-V)

Yield Strength

(ksi)164 110 162 126

Tensile

Strength (ksi)182 130 223 200

Elongation (%) ~4 10 12 ~30

Cold Work? Yes Yes No No

Heat

Treatment

SHT, cold

work, age

SHT and cold

work

Warm Work

and ageSHT and age

• QT Co has demonstrated better wear resistance compared to baseline

AMS4533 CuBe alloy.

• Additional interest from turbine engine OEMs

• Patent granted in EU; US and JP pending

p. 29

Jiadong Gong

SRG 2017

Summary

• ICME databases/tools for thermodynamic and process modeling

have been applied to the design of precipitate-strengthened high-

strength Ni-base and Co-base alloys for target applications

• The genomic design method significantly accelerated the materials

design, process development, and prototype production

• The novel Ni and Co alloys show excellent properties and high

potential for the specific applications compared with incumbent

• The methodology and technology used during the development of

these two alloys demonstrates flexible applicability and robust

capability

• Wider application of the computational genomic design has been

growing in related novel fields of materials technology, such as

Additive Manufacturing

p. 30

Jiadong Gong

SRG 2017

Thank you!

For more information, contact:

Jiadong Gong

Senior Materials Design Engineer

QuesTek Innovations

847.425.8221

jgong@questek.com

www.questek.com

p. 31

Jiadong Gong

SRG 2017

Back-up Slides

p. 32

Jiadong Gong

SRG 2017

List of benchmark alloys - IGT

Alloy Re Cr Co Mo W Al Ti Ta Nb Fe Hf C B Zr Ni Other?

QTSX 1 7.1 9.1 0.9 8 5.9 0.1 9.4 - - 0.1 - - - Balance

X45 - 25 Balance - 8 - - - - 1 - 0.25 0.01 - 10

ECY768 - 23.5 Balance - 7 0.1

5

0.2 3.5 - 1 - 0.6 0.01 0.05 10

FSX414 - 28 Balance - 7 - - - - 1 - 0.25 0.01 - 10

MGA2400 - 19 19 - 6 1.9 3.7 1.4 1 - - - - - Balance

U500 - 18 18.5 4 - 2.9 2.9 - - - - 0.08 0.006 0.05 Balance

IN738 - 16 8.5 1.7 2.6 3.4 3.4 1.7 - - - 0.17 0.01 0.1 Balance

IN939 - 22.4 19 - 2 1.9 3.7 - 1 - - 0.15 0.009 0.10 Balance

MAR M247LC - 8 10 0.6 10 5.5 1 3 - - 1.5 0.15 0.015 0.03 Balance

CM247LC - 8 9.3 0.5 9.5 5.6 0.7 3.2 - - 1.4 0.07 0.015 0.010 Balance

PWA1483 - 12.2 9.2 1.9 3.8 3.6 4.2 5.0 - - - 0.07 - - Balance

ReneN5 3 7 8 2 5 6.2 - 7 - - 0.2 - - - Balance

GTD222 - 22.5 19.1 - 2 1.2 2.3 0.9

4

0.8 - - 0.08 0.004 0.02 Balance

Nim155

Nimonic 263

p. 33

Jiadong Gong

SRG 2017

List of benchmark alloys - Aerospace

Alloy Re Cr Co Mo W Al Ti Ta Nb Hf C Ni Other?

QTSX 1 7.1 9.1 0.9 8 5.9 0.1 9.4 - 0.1 - Balance

PWA1480 - 10 5 - 4 5 1.5 12 - - - Balance

PWA1483 - 12.2 9 1.9 3.8 3.6 4.1 5 - - 0.07 Balance

GTD444 - 9.8 7.5 1.5 6 4.2 3.5 4.8 - 0.15 0.08 Balance

CMSX7 - 6 10 0.6 9 5.7 0.8 9 - 0.2 - Balance

CMSX8 1.5 5.4 10 0.6 8 5.7 0.7 8 - 0.2 - Balance

PWA1484 3 5 10 2 6 5.6 - 9 - 0.1 - Balance

CMSX4 3 6.5 9 0.6 6 5.6 1 6.5 - 0.1 - Balance

Rene N5 3 7 7.5 1.5 5 6.2 - 6.5 0.01 0.15 - Balance 0.01Y

CMSX10 6 2 3 0.4 5 5.7 0.2 8 0.1 0.03 - Balance

TMS238 6.4 4.6 6.5 1.1 4 5.9 - 7.6 - 0.1 - Balance 5.0Ru

p. 34

Jiadong Gong

SRG 2017

Performance at elevated temperature

Evolution of microstructures during long-term exposure at elevated temperature

Maintains phase fraction after

high temperature exposure

p. 35

Jiadong Gong

SRG 2017

Stress Rupture Samples: 1562F & 1742F

1562F/1255h 1562F/1693h 1742F/873h 1742F/1283h

Longitudinal

Transverse

p. 36

Jiadong Gong

SRG 2017

Stress Rupture Samples: 1800F

1800F/515h1800F/391h 1800F/455h

Longitudinal

Transverse

p. 37

Jiadong Gong

SRG 2017

Stress Rupture Samples: 1900F

1900F/210h1900F/149h 1900F/185h

Longitudinal

Transverse

p. 38

Jiadong Gong

SRG 2017

Stress Rupture Samples: 1922F & 2000F

1922F/747h 1922F/920h 2000F/160h

Longitudinal

Transverse

p. 39

Jiadong Gong

SRG 2017

Phase II oxidation trials

• In-air oxidation at 871°C (1600°F), 982°C (1800°F) and 1093°C (2000°F)• 100 hour at all three, 1000 hour at 982°C

• QTSX + ReneN5 (both fully aged)

• Mass change and oxide scale thickness change analyzed

Isochronal (100h) 982°C Isothermal

Δ Mass

Δ Thickness

p. 40

Jiadong Gong

SRG 2017

Phase II oxidation trials: oxide compositions

Elem. QTSX ReneN5

At% 871C 982C 1093C 871C 982C 1093C

O 48.7 59.4 59.8 51.8 59.6 57.6

Al 25.5 34.2 34.9 34 33.5 36

Si 8.0 4.3 4.2 2.6 4.1 4.5

Cr 4.1 0.8 0.2 1.9 0.6 0.4

Co 2.6 0.1 0.1 1.3 0.5 0.2

Ni 11.1 1.3 0.8 8.40 1.84 1.34

Note: 982C is 1000 hour, all others are 100 hour

p. 41

Jiadong Gong

SRG 2017

Thermal processing

Homogenization:

1285°C/4 hrs

1295°C/4 hrs

1310°C/8 hrs

Air Cool

Aging:

1121°C/4 hrs

871°C/20 hrs

Air Cool

p. 42

Jiadong Gong

SRG 2017

Thermal processing

• Microstructural evolution through

thermal processing path

As-cast

1285C 4 hrs 1285C 4 hrs,

1295C 4 hrs

1285C 4 hrs,

1295C 4 hrs,

1310C 8 hrs

1285C 4 hrs,

1295C 4 hrs,

1310C 8 hrs,

air cool,

1121C 4 hrs,

871C 20 hrs,

Air cool

Homogenization Age

p. 43

Jiadong Gong

SRG 2017

Testing results – thermal diffusivity

Thermal Diffusivity

p. 44

Jiadong Gong

SRG 2017

Testing results – specific heat

Specific Heat

p. 45

Jiadong Gong

SRG 2017

Testing results – thermal conductivity

Thermal Conductivity

p. 46

Jiadong Gong

SRG 2017

Testing results – thermal expansion

Thermal Expansion

p. 47

Jiadong Gong

SRG 2017

Testing results – coefficient of thermal expansion

Mean Coefficient of Thermal Expansion

p. 48

Jiadong Gong

SRG 2017

Testing results – tensile

p. 49

Jiadong Gong

SRG 2017

Testing results – stress rupture

• Still in-progress:

– 1562°F

• Stress:

– 55.8 and 66.9 ksi

– 1742°F

• Stress:

– 23.2 ksi

– 1922°F

• Stress:

– 13.1 ksi

p. 50

Jiadong Gong

SRG 2017

Next Steps

• Sulfidation testing at Cranfield in collaboration with Siemens

– QTSX vs. Rene N5

• Oxidation testing at Siemens

– QTSX vs. Rene N5

• Small cubes for dimension and weight

• Cast another round of test bars and build-out required test data

to allow for adoption considerations

• Coating design & development

p. 51

Jiadong Gong

SRG 2017

Summary

• Thermodynamic and process modeling ICME tools have been applied to

the design of L12 precipitate-strengthened high-strength wear-resistant

Co-base alloy

• Full-scale prototypes were produced and extensive performance testing

shows excellent properties and high potential for the alloy as a CuBe

replacement

• Simulation and validation of multi-step temper to reduce time to peak

strength

• Newest forging (with attempted larger deformation) has similar

microstructure as previous heats (with identical SHT and temper) and

similar properties (tensile, galling)

– No grain refinement achieved

• Improved bushing wear over CuBe

• Potential for improved properties with smaller grains

– SHT optimization

– Larger deformation

p. 52

Jiadong Gong

SRG 2017

0

5

10

15

20

25

30

0 5 10 15 20 25 30

Pre

dic

ted

Pre

cip

itat

ion

Str

en

gth

en

ing,

Ksi

Precipitate Radius (nm)

60

70

80

90

100

110

120

130

140

0 5 10 15 20 25 30

Pre

dic

ted

Yie

ld S

tre

ngt

h, K

si

Precipitate Radius (nm)

Precipitation strengthening Predicted Yield strength

22%

17.5%

16%

22%

17.5%

16%

Strength Modeling

For a fixed precipitate fraction, maximum strength is achieved at the precipitate size that precipitation shearing and Orowan looping effect equal.

APB energy is taken as 185 mJ/m

p. 53

Jiadong Gong

SRG 2017

Multi-step temper to reduce time

to peak strength

Alloy production (300 lb. VIM/VAR scale)

0 20 40 60 80 100

0

10

20

30

40

50

60

(

KS

i)

Time (hrs)

780C

800C

820C

780C+680C

800C+680C

820C+680C

Aging cycle Ave. tensile σy

Prior cycle

(1-step, 72h)

127.2 ksi

New cycle

(2-step, 48h)

127.3 ksi

DICTRA Simulations to Optimize

Homogenization Time

Strength Model* Calibrated to Peak Aged

Condition

*Kozar, R. W.et.al, Metall. Mater. Trans. 40A (7), (2009) 1588-1603.

Model validated by

experiment for

decrease in aging by

33%

p. 54

Jiadong Gong

SRG 2017

Precipitation Modeling

0

5

10

15

20

25

0.00001 0.0001 0.001 0.01 0.1 1 10 100

γ' Precipitation radius (nm)

0

0.05

0.1

0.15

0.2

0.25

0.00001 0.0001 0.001 0.01 0.1 1 10 100

γ' Precipitation Phase Fraction

0.00E+00

2.00E+25

4.00E+25

6.00E+25

8.00E+25

1.00E+26

1.20E+26

1.40E+26

0.00001 0.0001 0.001 0.01 0.1 1 10 100

Number Density (#/m^3)

Aging time (hr)

PrecipiCalc® and TC-PRISMA

simulation has been performed

to predict the evolution of the γ’

precipitates during the long

term aging.

Figures on the left demonstrates

the simulation results of the 780

°C isothermal aging.

The γ and γ’ interfacial energy is

set to a preliminary value of 30

mJ/m2 according to previous

studies. Further refinement of

the simulation requires

calibration of this term to give

better predictions.

p. 55

Jiadong Gong

SRG 2017

QuesTek Cobalt Alloy Property

Comparison • Designed for low-friction bushing applications as an alternative to high-strength

CuBe alloys– The new design has demonstrated better wear resistance in pin-on-disk and reciprocating wear tests,

compared to baseline AMS4533 CuBe alloy.

• Additional interest from turbine engine OEMs

• QuesTek patent pending

Room Temperature Tensile Property

QuesTek Cobalt*

Haynes 188(AMS 6508 Sheet)

Haynes 25(Hot-rolled +

Annealed Bar)

Haynes 556™(Hot-rolled +

Annealed plate)

Ultimet®(Solution

Treated Bar)

Stellite 6®(Investment

Cast)

Tensile Strength 200 ksi 137 ksi 147 ksi 116 ksi 147 ksi 115 ksi

0.2% Yield Strength

127 ksi 67 ksi 73 ksi 55 ksi 76 ksi 96 ksi

Elongation 33% 53% 60% 51% 38% 3%

Reduction in Area 28% - - - - 3%

Hardness, RC 38 30 41

*Based on initial evaluations of 2” round hot forged bar, solution treated and aged at 780°C, produced at 500 lb. VIM + VAR scale

p. 56

Jiadong Gong

SRG 2017

Conclusions and Future Directions

• Thermodynamic and process modeling tools have been developed/applied

to the design of high-strength wear-resistant Co-base alloys

• Nano-scale L12 precipitation strengthening was employed to achieve

required strength levels

• CALPHAD calculations and PrecipiCalc® simulations were performed to

optimize the design and the heat treatment process for higher strength

• The predictions are in good agreement with the experimental observations

of the microstructures and the compositions validated via SEM and LEAP

• A full-scale prototype has been produced and the initial testing shows

excellent properties and high promise for replacement of the Cu-Be alloys

• Future efforts will include

• Accelerate scale-up and manufacturing optimization

• Adapt to high-temperature aeroturbine applications