Using neutrons for in-‐situ observation of engineering
material behaviour
Joe Kelleher Instrument Scientist, ENGIN-‐X beamline, ISIS
Neutrons at ISIS
H-‐ ion accelerator
Proton (H+ ion) synchrotron
Second target station
First target station
Engin-‐X beamline
IMAT beamline
The ENGIN-‐X beamline
Incident beam
South detector bank
North detector bank
Engin-‐X layout Radial
collimator (defines
outgoing beam size)
Incident slits
Strain direction
(bank 1)
Diffraction detector (bank 1)
Diffraction detector (bank 2)
Strain direction
(bank 2) 45º 45º
Sample on translation / rotation table
Strain direction (transmission
detector)
Time of flight
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
16
18
20
22
24
26
28
β-Sn powder
Total cross section (barns)
Neutron wavelength (Å)
Experiment Calculation
Transmission detector
Types of experiment: trends from 1999 to 2011
0% 10% 20% 30% 40% 50% 60% 70% 80% 90%
100%
1999 (PEARL)
2002 2005 2008 2011
Strain scanning: welds
Strain scanning: other
In-situ loading, room temperature
In-situ loading, high temperature
Other in-situ processes
Physics of neutron measurement
In-situ loading, cryo-temperature
Shar
e of
use
r ex
per
imen
t ti
me
From materials to processes Magnetic fields
Electrochemical reactions
Mechanical deformation
Heat treatment
Phase transformations
Welding
Fuel cells
Corrosion
Shape memory alloys
Material forming
Stressrig (up to 100kN)
Cryostat Down to -‐200C
Optical furnace
Up to 1100C
Resistance furnace (small samples, up to ~1600C)
Sample environments for in-‐situ tests
Ceramic heating pads (larger samples)
In-‐situ heat treatment
Linear weld Ni superalloy Circumferential pipe weld
Single crystal Ni superalloy
Anna Paradowska demonstrates proof of principle
James Rolph et al. Comptes Rendus
Physique 13(3):307–15. (2012)
Bo Chen et al. Acta Materialia submitted (2013)
See γ’ misfit as function of temperature
In-‐situ heat treatment of pipe weld
2.865
2.87
2.875
2.88
2.885
2.89
2.895
2.9
0 200 400 600 800
Atom
ic la*ce sp
acing / Å
Temperature / ° C
Weld... Stress-‐free reference...
Hea8ng Hea8ng Cooling Cooling
Bo Chen, Alexandros Skouras, Yiqiang Wang, Joe Kelleher, Shu Yan
Zhang, David Smith, Peter Flewitt, Martyn Pavier
Cyclic voltage on PZT ferroelectric
100 MPa applied
Zero load
The MANTID platform § Data reduction and visualisation
for all ISIS instruments § Supports event mode and
stroboscopic data
David Hall, 2013
Loading direction Transverse direction
500 V / mm AC electric field
Cyclic electric field causes straining of poled PZT, but applied load
depoles the PZT
Plots show difference between + and – half-‐cycles
–
+
In-‐situ welding
Fatigue crack growth
Practical considerations
• Sample environment – Sufficiently non-‐interacting with neutron beam – ‘Contains’ the process for steady-‐state, safety
• Timing for dynamic effects – Synchronise clocks or use trigger pulses – Get event mode acquisition to collect other data
• Can we record more than just the neutron data?
Supplementary analytical methods
Things that might change in a process
• Mechanical deformation, stress and strain
• Material ‘damage’ • Phase changes • Diffusion • Temperature
Methods that might reveal these changes
• Image correlation • Acoustic emission • Thermoelastography • Dilatometry • Calorimetry • Ultrasonic and magnetic
methods
• Sometimes possible to measure these ‘for free’ with existing sensors
Full-‐spectrum imaging
• Neutron detectors not intrinsically sensitive to wavelength, but to time of detection – …hence velocity, hence wavelength
• Each pixel of a 2D detector can record a full wavelength spectrum
• We can thus see both spatial and temporal variation in several physical parameters
Time-‐of-‐Klight neutron imaging for in-‐situ studies
Bragg edges show crystal structure – how those atoms are arranged
Resonance peaks show which atoms/isotopes present
Wavelength
Detected intensity
Height → Texture
Height → Concentration
Width → Temperature Position → Strain
Steven Peetermans & Joe Kelleher (2013) 17
Transmission spectrum from single crystal
Σabs+Σinc+Σinel,coh
Σel,coh Position = Orientation and strain
Width = Mosaicity
Conclusion: Some future directions?
• Broader array of sensing and actuation on beamlines – Users won’t need to bring their own
• Flexible data chopping with event mode – Especially cyclic or highly dynamic processes
• Sensor / actuator bus for real time measurement and control (e.g. CANBUS for vehicles)
