Nuclear Materials

Find out more with our Nuclear Materials applications note

Have you considered the effect of operating temperatures and high strain rate impacts on your materials?

The NanoTest Xtreme offers many benefits for characterising the next generation of reactor materials:

Mechanical properties of helium irradiated tungsten

The load-partial unload technique enables characterisation of mechanical properties at a single location on a surface as a function of depth. On irradiated samples it quickly clearly reveals any changes in properties in the thin irradiated layer compared to unimplanted material. The data shows an irradiation effect below 400 nm which is not present in deeper indentations.

The data in figure 1 provide strong evidence for the implanted He+ ions not diffusing into the bulk at high temperature since hardness was the same during heating and cooling (the circles were during heating and the stars during cooling back from 750 ºC to room temperature).

Figure 1 - Load-partial unload experiment on a tungsten sample at 650 ?C. b) The effect of alpha particle irradiation on the high temperature hardness of tungsten. Data courtesy of DEJ Armstrong, J Gibson, SJ Roberts, University of Oxford, MSEA Volume 625, Pages 380–384 .

Figure 1 – Load-partial unload experiment on a tungsten sample at 650 C. b) The effect of alpha particle irradiation on the high temperature hardness of tungsten. Data courtesy of DEJ Armstrong, J Gibson, SJ Roberts, University of Oxford, MSEA Volume 625, Pages 380–384 .

Creep behaviour of ODS steel

Figure 2 - Nanoindentation creep data from oxide dispersion strengthened steel. Data courtesy of P Hosemann, UC Berkeley.

Figure 2 – Nanoindentation creep data from oxide dispersion strengthened steel. Data courtesy of P Hosemann, UC Berkeley.

Nanoscale creep testing allows rapid assessment of the creep behaviour of small volumes of material. This allows testing of small samples of in service components as well as examination of the properties across welded sections.

Figure 2 shows nanoindentation creep data from experiments on oxide dispersion strengthened steel. The data shows clear differences in the creep rates of irradiated and non-irradiated alloy both at room temperature and 300 ?C.

The ability to perform tests at elevated temperatures allows simulation of conditions in different power plant locations allowing determination of relevant mechanical properties.

Mechanical property mapping across simulated P92 steel pipe weld cross section

Figure 3 - Change in nanoindentation hardness across a P92 matched weld at 675 C. Data courtesy of MI Davies and NM Everitt, University of Nottingham.

Figure 3 – Change in nanoindentation hardness across a P92 matched weld at 675 C. Data courtesy of MI Davies and NM Everitt, University of Nottingham.

In addition to using indentation to determine the mechanical properties at a single point on a sample grids of indentations can be used to map changing mechanical properties due to differences in grain structure or material composition.

Figure 3 shows the change in hardness across a simulated weld repair at 675 ?C. A line of indentations was made through the fusion line from the bulk weld to the bulk parent material.This experiment highlights the clear change in hardness as the indentations are placed in the different microstructures of the heat affected zone of the parent material.

The ability to perform these experiments at elevated temperature provides more relevant accurate data for weld repair lifetime predictions

 

Strain rate sensitivity measurements beyond the range of conventional nanoindentation

Figure 4 - The effect of irradiation on the energy damping behaviour of a structural steel.

Figure 4 – The effect of irradiation on the energy damping behaviour of a structural steel.

Micro Materials’ patented nano-impact technique allows material properties to be explored at strain rates of up to 1000 per second.

This allows examination of the strain rate sensitivity and energy damping behaviour of materials at much higher energy densities than conventional nanoindentation.

Figure 4 shows the effect of surface modification with 350 KeV Argon ions on ferritic steel. The implantation modifies the energy damping behaviour of the steel as shown by the slower decay of the displacement curve observed for the irradiated sample. This could impact the working lifetime of the steel component.0

Summary

The NanoTest Xtreme offers a wide variety of advantages to researchers trying to develop the next generation of materials for Nuclear Energy applications:

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