The Materials Division at NPL has a new underpinning activity, funded by the NMO in the Materials and Modelling Programme, to develop and integrate measurement and modelling tools. These will characterise and generate fundamental understanding of mechanical properties and material characteristics at the sub-grain level.

This bottom-up approach, focused on 3D structural, compositional and mechanical characterisation, will be coupled with mathematical modelling and macroscopic property and performance measurement in complementary projects. This will provide the springboard for the development of materials with engineered properties and for prediction of material performance in service from fundamental principles.

To facilitate this work, NPL has invested over £1 million in a state-of-the-art Focused Ion Beam Scanning Electron Microscope (FIB-SEM). The ion beam is used to mill away material in slices while the electron beam scans each slice to produce images or maps of the material's structure and chemistry with nanometre resolution. Combining the maps reconstructs the material structure in 3D. The strength of a material at a precisely chosen point in the structure can also be measured on ion beam milled test pieces much smaller than a grain of sand. With this knowledge models can be developed that predict the bulk material properties such as strength or resistance to failure by fracture, corrosion and wear.

New FIB-SEM test system.	Cube with 3 µm side showing structure of WC-15%Co hardmetal. Note that the yellow WC phase is semi-transparent in this visualisation revealing the sub-surface regions of red cobalt as orange.

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