Work carried out @

Chalmers, Sweden

Projects involved: Gear materials ---2010-12 NiTi Shape memory alloy ---2011-11 to 2012-06 VOLVO – low temperature creep --- 2011-11 to 2012-10 HIPERSINT Project --- 2012-07 to now INDUCTIONSINTERING --- 2013-04 to 2013-10 HÖGANÄS – Lit. review – XX steel --- 2013-01 Failure analysis – Borealis --- 2013-11 to 2013-12 KTH – JMatPro simulations –DOMEX --- 2013-10 to 2014-01 GKN-KME project --- 2014-01 to now

Activities: • Calibration of DSC (NETZSCH) • Atom Probe Tomography - Course attended • Poster – Materials for Tomorrow • Poster and demonstration – MPL opening • Poster – EuroPM2013 on NiTi shape memory alloy • Talk – EuroPM2013 on Low temperature Creep • Reviewer - JALCOM – 3 articles (total:9)

- Materials and Design – 1 article

Different microstructures but same composition

Finding critical feed rate

Manganese sulfide 20 40 60 0 A higher Bindex indicates better machinability

A Bindex of 100 represents the machinability of a free cutting steel

Ranking of materials by a Bindex

Chip morphology

TEM

Microstructure

Tool wear

Chip formation

Cutting forces

Build-up edge formation

Surface roughness

Machinability

80 100

Microstructure Machinability

Materials and Manufacturing Technology

FFI - Sustainable Gear Transmission Realization

Polar diagram - CLP

SEM material - CLP

SEM chip - CLP

Materials and Manufacturing Technology

TEM of a case hardening steel

Area Fe (At%) Cr (At%) Mn (At%)

All 96.76 1.63 1.75 A 86.60 7.08 6.72 B 93.43 4.34 2.22 C 100 0 0 D 86.29 7.57 6.13 E 98.75 0.73 0.57

A

B C

D

E

Coarse Lamellar Pearlite – Pearlite structure

Materials and Manufacturing Technology

Area Fe (At%) Cr (At%) Mn (At%)

All 96.04 1.97 1.99 A 82.48 12.37 5.15 B 83.45 10.93 5.62 C 97.43 1.11 1.46 D 96.67 1.35 1.98 E 81.96 11.41 6.63

A

B C D

E

Coarse Lamellar Pearlite – Precipitates

TEM of a case hardening steel

Ferrite microhardness in materials and chips

LNPm

at

SNPm

at

LNP0

5

LNP0

8

LNP1

SNP0

5

SNP0

8

SNP1

0

50

100

150

200

250

300

350

400

Micr

ohar

dnes

s HV

0.2

5

Microhardness results of chips can reveal strain hardening after machining. Microhardness results show higher hardness values at lower loads and following Meyer’s Law. The microhardness of chips is greater than the material due to high deformation. There is no clear trend in the chips of different feeds (feeds 0.05, 0.08 and 0.1mm/rev).

Material A Material B Material C Material D

Strain hardening at 25°C

0.1154 0.1183 0.1151 0.1134

at 600°C 0.1357 0.137 0.1336 0.1345

Strain hardening From the literature and data for 20MnCrS5, the strain hardening exponent: 0.11- 0.12 at RT Strain hardening depends on grain size and pearlite morphology According to JMatPro Considering 0.2% proof stress at 1e5 strain rate

the strain-hardening exponent n increases with increasing grain size in a certain range and decreases with increasing volume fraction of second phase for a given particle size*

* Zhang Fan et al., Materials Science and Engineering: A, Volume 122, Issue 2, 20 December 1989, Pages 211-213

XRD scan of NiTi gas atomized powder

XRD scan of starch consolidated and sintered sample

DSC scan of NiTi gas atomized powder

As Af

DSC scan of starch consolidated and sintered sample

As Af

Starch sintering As and Af shifted to higher temperature

Production of porous NiTi bulk shape memory alloy by starch consolidation and sintering

To produce porous samples by starch consolidation and sintering method using pre-alloyed NiTi powder for biomedical applications

NiTi - Starch consolidation and sintering

Blend

Mold

Consolidate (~75°C)

Freeze (‒20°C)

Demould

Dry

Green body Sinter in

argon (~1255°C)

• Production of samples: Starch consolidation and sintering, using experience from loose powder sintering.

• Evaluation of samples: • Porosity: Geom. and mass measurements. • Microstructure: XRD, DSC, OM, SEM and EDX. • Mechanical properties: Compression testing, cyclic loading

and microhardness tests.

Principle of starch consolidation

Slurry (left) with unconsolidated starch particles (white) and metal powder particles (grey) is heated to the consolidation temperature at which the starch consolidates

A demoulded and fully dried out sample next to its mould

EDM

NiTi – OM and SEM starch consolidation and sintering

Combined optical micrographs: porosity ~25

SEM images of starch sintered sample

SEM images of starch sintered sample. Various types of particles and phases were identified from EDX measurements: Fig a) shows the greyish areas which areTi4Ni2O or Ti2Ni Fig b) shows the dark particles which are TiC Fig c) shows Ni4Ti3 particles in NiTi matrix Fig d) shows large irregular particles which are Ni4Ti3 or Ni2Ti

Ø: 26 mm h: 8-10 mm

NiTi –starch consolidation and sintering Mechanical Properties

Residual strain: 2.1 % After anneal: 1.0 % Recovery: >50 %

Illustration of compression test samples by EDM from a sintered sample

Starch consolidated and sintered sample (polished)

Engineering stress-strain curves from compression test of a starch consolidated and sintered sample

Cyclic compression testing of a starch sintered sample

• sy > 1 GPa • su > 2 GPa • E > 25 GPa

Low Temperature Creep/Relaxation in PM Steels under Static Load

Water atomized iron powder prealloyed with Mo-1.5%

Alloying elements Ni-4% & Cu-2%

(diffusion bonded)

Diffusion alloyed powder grade from Höganäs AB

Samples Distaloy HP Denominations Description

1 DHP-UT Untempered 2 DHP-T200 Tempered at 200°C for 1 hour 3 DHP-T300 Tempered at 300°C for 1 hour

1

2

3

Material : Distaloy HP DHP-UT DHP-T200 DHP-T300

Tensile testing

Metallography

Austenite analysis by stress tech Xstress 3000

Hardness Apparent Hardness

Microhardness

Creep testing

Cyclic creep

1 million seconds ( ~ 277 hours)

Varying parameters

Instron universal testing machine with environmental chamber

Experimental Methods

14

Creep tests – 1 million seconds (~277 hours)

varying temperature

varying stress

Creep tests – with varying parameters

XRD : Master alloy Ni48Mn8B

HIPERSINT Code Description Density g/cc 3A - X-Astaloy 0,45Mo + 2,5%MA-20µm + 0,3%C-UF4 + 0,4%LubeE 7.1 and 7.3 3B - X-Astaloy 0,45Mo + 2,5%MA-45µm + 0,3%C-UF4 + 0,4%LubeE 7.1 and 7.3 4A - X-Astaloy 0,2Mo + 2,5%MA-20µm + 0,3%C-UF4 + 0,4%LubeE 7.1 and 7.3 4B - X-Astaloy 0,2Mo + 2,5%MA-45µm + 0,3%C-UF4 + 0,4%LubeE 7.1 and 7.3

Effect of MA particle size

Effect of Mo content

Effect of density

HIPERSINT - Dilatometry

18

Astaloy CrA 20µm MA Density 7.1

Spectrum Label

B Cr Mn Fe Ni Total

Spectrum 1 13.12 5.19 1.35 80.34 100.00 Spectrum 2 1.85 1.07 96.19 0.89 100.00 Spectrum 3 3.11 1.19 94.76 0.93 100.00 Spectrum 4 12.62 4.56 1.33 81.49 100.00 Spectrum 5 1.76 1.18 95.91 1.16 100.00 Spectrum 6 1.87 1.09 95.98 1.07 100.00 Spectrum 7 13.26 5.31 1.47 79.96 100.00 Spectrum 8 12.38 4.47 1.48 81.66 100.00 Spectrum 9 1.85 1.40 95.41 1.34 100.00 Spectrum 10 1.74 1.55 95.30 1.41 100.00

HIPERSINT

19

X-Astaloy0.2Mo 45µm MA

Density 7.1

Density 7.3

HIPERSINT

8th International Symposium on Superalloy 718 and Derivatives September 28-October 1, 2014 Marriott City Center • Pittsburgh, Pennsylvania

22

Work carried out during Ph.D @ IFW Dresden

• Mechanical alloying - Al-Y-Co-Ni (from elemental powders)

• Mechanical milling - Al-Y-Ni-Co - Al-Ni-La (melt spun ribbons) • Consolidation by HP and SPS - Al-Y-Ni-Co and composites (from milling) - Al-Y-Ni-Co - Al-Ni-La Gas atomized powders - Al-Gd-Ni-Co - Al-Nd-Ni-Co

• Spray deposits - Al-Y-Ni-Co - Al-Si Characterization and mech. properties - Al-Y-Ni-La-Co

• BMG ductilization - Vitreloy1 - Vitreloy 105 preparation, characterization, - Zr-Ti-Ag-Cu-Ni-Al mech. properties, surface modifications • Quasicrystals - Al-Cu-Fe • Laves phases - Fe-Zr, Fe-Zr-Cr • Crystallization kinetics - Al-Y-Ni-Co and Al-Gd-Ni-Co

23

XRD

• GAP : Amorphous

• 1st DSC peak : Amorphous fcc Al

• 2nd DSC peak : Amorphous

fcc Al + Al19Gd3Ni5 and Al9Co2

SEM

XRD (Co-Kα) Viscosity (10 K/min)

Viscosity

• viscous drop at Tg due to

super cooled liquid

Source : Ames Laboratory, Ames (USA) Size : d0.5 ~20 µm Morphology : smooth, round & satellites (< 1 µm) Microstructure: mostly featureless, large particles with crystallites

DSC (40 K/min)

DSC

• clear glass transition region

• two exothermic events

Al84Gd6Ni7Co3 Gas atomized powder

24

Al84Gd6Ni7Co3 – Crystallization kinetics

• activation energy (Ea) by the Kissinger method

• • Johnson-Mehl-Avrami

equation • .

• .

• .

[ ]( )nT tKtX )(exp1)( τ−−−=

−=

RTEKK A

T exp0

)ln(ln1

1lnln τ−+=

−tnKn

X T

Avrami exponent n can vary from 1 to 4 the transformation mechanism, such as the nucleation and growth behavior > 2.5 - increasing nucleation rate of all shapes; 2.5 - constant nucleation rate; 1.5-2.5 - decreasing

nucleation rate; 1.5 - zero nucleation rate; 1- needles and plates and thickening of long needles

25 1/6/2011 Surreddi-PhD defense

Al84Gd6Ni7Co3 – hot pressing Hot pressing at 573 K

at 623 K

at 673 K

at 723 K

26

Strength level similar to Zr- and Ti-based metallic glasses (but with strain hardening) Strength 3 times higher than high-strength conventional Al-based alloys High-strength combined with good plasticity due to UFG/nc Al and nc intermetallic compounds Best combination of strength and plastic strain for hot pressing at 673 K (full densification + retaining nano-sized microstructure)

HP Temperature

(K)

Yield stress σy (MPa)

Fracture stress

σf (MPa)

Fracture strain εf (%)

573 -- -- -- 623 -- 700 -- 673 1250 1560 3.5 723 1150 1440 4 773 900 1280 5.5

Ext-723 K 800 1130 3

Compression testing : • Instron 5869 testing facility • Compression test samples : 3 mm diameter and 6 mm length

RT compression test; strain rate 1× 10-4

Mechanical Properties

27

DSC:

No visible glass transition

2 exothermic events

Viscosity:

2 distinct viscosity drops

XRD:

As-atomized microstructure

: amorphous + fcc-Al

1st DSC peak : formation of fcc-Al

2nd DSC peak : formation of Al11La3 + Al3Ni

XRD (Co-Kα) DSC (40 K/min) (inset - Viscosity (10 K/min))

Gas atomized Al87Ni8La5 alloy powder

SPS at 713 K

28

Dark areas between particles - fcc-Al Bright particles - nanosized Al3Ni and Al11La3

Network of ultra fine-grained (UFG) Al reinforced with nm-scale intermetallic particles

Bright layers at the particles interface good densification efficient bonding

SPS sample sintered at 713 K

SPS - Al87Ni8La5 alloy

500nm 100 nm

SPS - Al87Ni8La5 alloy

30

0 5 10 15 20 25 300

200

400

600

800

1000

SPS 713 K

SPS 643 K

True

stre

ss (M

Pa)

True strain (%)

SPS 573 K

550 600 650 700280285290295300305310315320

Sintering temperature (K)H

ardn

ess (

HV)

920

940

960

980

1000

1020

1040

Maxim

um stress (M

Pa)

() Hardness () Maximum stress

With increasing sintering temperature • hardness decreases • maximum stress decreases Grain growth

Compressive strength: 900 – 1000 MPa Plastic strain: 10 – 25 % The fcc Al within the structure, are not confined and the continuous network of fcc Al allow the movement of dislocations, explaining the remarkable plastic deformation

RT compression test; strain rate 1× 10-4

Mechanical properties

Al-based metal matrix composites (MMCs) by powder metallurgy good microstructure control (volume fraction, size and morphology)

tunable mechanical properties good matrix – reinforcement interface low processing temperature

Matrices: pure Al and Al-based alloys

Reinforcements: metallic glasses (high strength 1 - 2 GPa, large elastic strain 1 - 2 % …) complex metallic alloys (CMAs) (high strength to weight ratio, HT strength ...)

quasicrystals (QCs) (high hardness, compatible thermal expansion coefficient …)

Processing route 1) reinforcement production by mechanical alloying/milling 2) matrix - reinforcement mixing 3) consolidation by hot pressing - hot extrusion

Al-based metal matrix composites (MMCs)

Pure Al + BM Al85Y8Ni5Co2 glassy ribbons (30 and 50 vol.%)

Glass-reinforced Al-based MMCs

XRD (Co-Kα)

DSC (40 K/min) Viscosity (10 K/min)

Rel. Density

Pure Al + BM Al85Y8Ni5Co2 glassy ribbons (30 and 50 vol.%)

Glass-reinforced Al-based MMCs

Scudino et al., J. Mater. Sci. 43 (2008) 4518

Al-based glassy flakes effective reinforcement strength 1.5 − 2 times higher than pure Al combined with good plastic deformation

BUT reinforcement production is very complex

RT compression tests

Spray Deposition - Al83La5Y5Ni5Co2

deposit and substrate

SEM micrographs of deposit OM micrographs of deposit

Laves phases and in situ LP composites

Fe90−xZr10Crx alloys (x = 0, 5 and 10) containing cubic C15 and hexagonal C14/C36 Laves phases in an ultrafine eutectic matrix of α-Fe

Laves phases and in situ LP composites

As-cast Fe80Zr10Cr10 rods with different mold diameter (Φ = 1, 2, 3 and 4 mm)

(a) Φ = 2 mm diameter (b) Φ = 1 mm diameter As-cast 4 mm diameter Fe80Zr10Cr10 rod

37

Metallic Glasses have amorphous structure, with short range order (< 1-2 nm)

Bulk means: 3D sample size not less than 0.5-1 mm in any dimension

Empirical rules of Glass Forming ability (GFA)

Multi-component alloy system

Atomic size difference above 12%

Negative heat of mixing among contituent elements

Tg/Tm > 2/3 deep eutectic high cooling rates to supress crystallization

• pure metals 1010 – 1012 K s−1

• binary alloys 104 – 106 K s−1

• multicomponent alloys 102 K s−1 or less

Metallic Glasses and Glass Formation ability

38

Copper Mold Casting

Melt Spinning

Planetary Ball Mill

Hot Pressing

Compacted Samples

Cast Samples Master Alloy

Amorphous and glassy materials preparation

BMG preparation

39

Bulk metallic glasses

Merits of metallic glasses:

unique properties / combinations

High hardness/ strength/elastic strain Corrosion and wear resistance

Drawbacks of metallic glasses

No classical work hardening

Brittle at room temperature

Localized deformation by shear banding

Possible ways to solve

Heterogeneous microstructure

Different scale / morphology

Casting, powder metallurgy

40

USB flash drive casing Products from BMG Schroers lab – Yale University

Apple’s iphone SIM card ejection tool

Swatch Group watch parts Golf clubs

Applications from Liquid metal technologies

Blow molding

Bulk metallic glasses - Ductilization

• designed-heterogeneities

BMG - cold-rolling Zr52.5Ti5Cu18Ni14.5Al10

Cu47.5Zr47.5Al5

BMG- frictional-boundary-restraints

Zr41.2Ti13.8Cu12.5Ni10Be22.5

BMG - channel-die-compression

@ Chalmers, Sweden

HR-SEM TEM XPS

Instron 5500R with 4505 load frame with Instron 3119-407

environment chamber

• Optical microscopy - Zeiss • Microhardness - Shimadzu • XRD – Bruker D8 • Stress tech – X3000 • STA 449 F1 and DIL 402C

@ IFW Dresden, Germany

Hot Press and Extrusion

Centrifugal casting Melt spinning Drop casting

Planetary ball mill Perkin Elmer DSC

• Arc melting • Nanoindentation • Microhardness • Instron 5869 • Modulus – Ultrasonic • Viscocity - DMA