“Materials for Fission & Fusion Power”

Steve Roberts

SergeiDudarevCCFE

George Smith

Gordon TatlockLiverpool

Angus Wilkinson

Patrick Grant

AndrewJonesLiverpool

SteveDonnellyHuddersfield

SergioLozano-Perez

Michael Moody

James Marrow

SteveFitzgerald

Chris Grovenor

Paul Bagot

“Materials for Fission & Fusion Power”

MFFP: Hot topics• ODS alloy processing

– Microstructural development– Joining– Novel processing

• Small-scale <-> large scale mechanics– plasticity and fracture; temperature effects– “pure” materials– Dispersion strengthened materials– Radiation damaged materials

• Alloy stability under irradiation• Crack chemistry and fracture• Helium and radiation damage• Neutrons Ions ( Protons)?

Irradiation effects

1-100 displacements per atom100’s ppm heliumTransmutation radioactivity

Fast neutron test reactor, hot cells

…or…

Irradiation effects

1-100 displacements per atom100’s ppm heliumTransmutation radioactivity

Fe+ / W+

H+ , He+

2 - 30 MeV

~0.5 - 4 mm

Steel,Tungsten,….

electrons

ions

In-situ irradiation of Fe at 300°C

Dose increment: 6~10 dpa; viewed 40 x real time

25 nm

– these are interstitial loops with b = ½ [-111]

Oxide – Dispersion - Strengthened alloys: radiation resistanceNo irradiation 0.5 dpa

1 dpa 2 dpa

Particles stable, and no radiation damage was visible below 1 dpa

ODS PM2000, RT irradiated with 150 keV Fe+, room temperature

Atom-Probe: Radiation-induced clustering in Fe-Cr alloys

Implanted depth ~500-

1000nm

• FIB “lift out” preparation

(Fe not shown)

2nm thick slice

Clusters

Clusters only

post

Pt

Fe-Cr alloy

• Cr clustering observed in Fe-3%Cr (associated with C)

• Fe-3%Cr should be STABLE according to equilibrium phase diagram

• Cr clusters produce hardening and embrittlement

58nm

42 nm 42 nm

Fe-3at.%Cr alloy

Atom probe tip300°C, 2MeV Fe+ 1dpa

1mm

Hardness (GPa)

Fe – x% Cr

Unimplanted

Low dose rate

High dose rate

Low dose rateHigh dose rate

Mechanical effects: dose rate

Low dose rate

High dose rate

At lower dose rate, Cr clusters form on dislocation loops- much greater hardening effect

Irradiation effects in W: Nanoindentation

W+

2 MeV

He+

W+ W+

He+

He+unimplanted

W+

unimplanted

He+

W++He+

Hardness (GPa)

Micro-mechanical Testing

50mm

Un-irradiated

Irradiated

FIB Milled Line

5 mm

Microcantilevers produced by Focussed Ion-Beam

Micro-mechanical Testing: Tungsten

20mm

Unimplanted

W Implanted

W&He Implanted

Yield Stress(GPa)

2.0±0.9(4 Cantilevers)

3.1±0.7(4 Cantilevers)

3.1±0.7(7 Cantilevers)

Fracture Toughnes

s(MPa√m)

>29±12(0/2

Cantilevers)

>15±3(0/4

Cantilevers)

17(1/7

Cantilevers)

1mm

Active Material: Fe-6%Cr N-irradiated to 1.7 dpa at 288°C, dose rate ~1 x 10-7 dpa/s

0.1mm

FIB work at CAES, Idaho

▫ 66 cantilever beams with depths from 0.82 to 7.3μm▫ Also made in

▫ Ion-irradiated Fe-6%Cr, same dpa & temperature

▫ Unirradiated

1mm

Activity: 37MBq

0.00E+00

1.00E+09

2.00E+09

3.00E+09

4.00E+09

5.00E+09

6.00E+09

7.00E+09

0.000 1.000 2.000 3.000 4.000 5.000 6.000 7.000 8.000

Yiel

d St

ress

(Pa)

Beam Depth (μm)

Simple Yield Stress

Neutron Irradiated

Ion Irradiated

Un-Irradiated

Power (Neutron Irradiated)

Power (Ion Irradiated)

Power (Un-Irradiated)

Neutron-irradiated

Unirradiated

Ion-irradiated

Micromechanical testing Fe-6%Cr – yield stress

-100°C +750°CWorld-unique

Si: 500°C

Si: 700°C

Micro-mechanical Testing: Temperature

Oxford Nuclear Materials: Capabilities

• Electron Microscopy– Defects & damage– Chemical microanalysis– In-situ with ion-beam,

heating

• Atom-probe tomography – Atomic-scale chemistry

• Focussed ion-beam sectioning– Selected local areas for

EM and APT

• Small-scale mechanics– Small active specimens– Thin ion-irradiated layers– -100°C to +750°C

• Modelling (with CCFE)– Defects– Mechanics– Transmutation paths

• Links to “radiation-effects” projects internationally– NNUF– NEUP/IRP– (FAFNIR), (TRITON)