The MPISI (Zulu name for the spotted hyena) material science neutron diffraction instrument is located at the SAFARI-1 research reactor of the South African Nuclear Energy Corporation (Necsa) SOC Limited.
It is optimized for non-destructive depth-resolved studies of internal strain in bulk structures originating from manufacturing processes and in-service loads.
By exploiting the superior penetrating capabilities of neutrons MPISI provides a valuable analysis technique for cutting-edge research in materials engineering and related scientific disciplines.
The instrument configuration also allows for the investigation of crystallographic texture in engineered processed materials and natural geological samples.
Typical samples that have been comprehensively investigated include:
- Welded steel plates (up to 30 mm in thickness),
- Aluminium ring and plug specimen with 50 mm diameter,
- Additive manufactured titanium and steel specimens,
- High-resolution investigations, i.e. depth resolution and near surface stresses:
- Laser shock peened aluminium plates 3.3 mm in thickness,
- Laser welded and shock peened aluminium plates 3.3 mm in thickness,
- Laser treated steels.
MPISI is designed to be on equal standing with similar instruments at leading international facilities. State-of-the-art data acquisition, control and analyses systems enable measurement of complex multi-dimensional strain maps of samples whilst optimising neutron beam utilisation.
By employing micro-stepping, in conjunction with surface scans, samples can be positioned to within 10 µm accuracy.
|Flux at sample position:|
|Double focused bent perfect Si crystal|
|2.53, 1.01, 1.65 & 0.93|
|Manually adjustable:0.3 – 5 mm horizontal0 – 20 mm verticalRadial collimators: FWHM of 1, 2 ,5, 10 mm|
|Denex-300TN 3He filled300 mm (hor.) x 300 mm (ver.)Range: 10° ≤ 2θ ≤ 110°|
|Huber integrated XYZ Maximum sample weight: 250 kgXYZ Linear travel: 250 mm¼ cradle with integrated Φ,χ,XYZ|
|Various chucks, CNC machine vices etc.|
|106 neutrons cm-2s-1|
Resolution curve of the MPISI instrument measured from NIST standard silicon powder.
1. Aluminium ring and plug specimen [GA Webster (ed.), “Neutron Diffraction Measurements of Residual Stress in a Shrink-fit Ring and Plug” 2000 VAMAS Report No. 38 ISSN 1016-2186]
2. Hot rolled, followed by cold rolled, aluminium plate 3.3 mm in thickness: Correlation of stress results measured on MPISI (Necsa: investigated with a gauge volume of 0.6 x 15 x 0.6 mm3) and Kowari (Ansto, Bragg Institute, Australia: gauge volume of 0.2 x 15 x 0.2 mm3 )
3. Depth-resolved residual stress determination of Laser Shock Peening (LSP) treated aluminium alloy 7075-T651 samples (6 mm and 1.6 mm thickness) using complementary techniques. [S.N van Staden, C. Polese, D. Glaser, J.-P. Nobre, A.M. Venter, D. Marais, J. Okasinski, J.-S. Park.
Measurement of Residual Stresses in Different Thicknesses of Laser Shock Peened Aluminium Alloy Samples. Materials Research Proceedings 4 (2018) 117-122 (http://dx.doi.org/10.21741/9781945291678-18)]
4. ISO/TC 135/SC 5/WG 7: Modernisation of ISO/TS 21432 “Non-destructive testing – Standard test method for determining residual stresses by neutron diffraction”, for review as International Standard in 2016. Participation member of project team. Published as ISO 21432:2019.
5. Participating member of the BrightnESS² project entitled “Bringing Together a Neutron Ecosystem for Sustainable Science with ESS” which aims to establish a calibration protocol for all strain scanning instruments and definition of criteria for the Neutron Quality Label.
Estimate of data acquisition times:
The graphs below give an indication of data acquisition times required for the materials alpha-iron (mild steel), aluminium and titanium to attain strain accuracies of 50 microstrain at gauge volume sizes as indicated in the graph legend.
Measurement times and gauge volume sizes are interdependent and governed by the strain resolution required.
As a guide, when using a gauge volume of 5 x 5 x 5 mm3, up to 30 mm thick steel plates can be investigated non-destructively.
Data reduction and analysis:
Data reduction is primarily performed in-house using custom-developed software called ScanManipulator and is available online here: https://github.com/Deon-Marais/ScanManipulator
[D Marais, A.M. Venter and J Markgraaff, Data processing at The South African Nuclear Energy Corporation SOC Ltd (Necsa) neutron diffraction facility. Proceedings of SAIP2015. (2016) 198-203. (ISBN: 978-0-620-70714-5)]
Referencing the instrument in publications:
A.M. Venter, P.R. van Heerden, D. Marais, J.C. Raaths, MPISI: The neutron strain scanner materials probe for internal strain investigations at the SAFARI-1 research reactor, Physica B: Physics of Condensed Matter 551 (2018) 417-421. (http://dx.doi.org/10.1016/j.physb.2017.12.011)
Dr. Deon Marais
B.Eng Computer and Electronic; M.Eng & PhD Nuclear
+27 (0) 12 305 5645
Prof. Andrew Michael Venter
+27 (0) 12 305 5038
Apply for beam time:
Please download the beam time request form here and return to the instrument scientist.