|Materials and Modelling|
|Dr Oliver Payton and Dr Loren Picco|
The macro sized physical properties of a material are a product of the nano and micro sized structures within. The materials used in the Nuclear industry are no different. In order to better predict the lifespan of a piece of plant or storage apparatus it is vital to know how these nanostructures are affected by the harsh and unique environments to which they are exposed. It is also important when designing the next generation of materials for the nuclear industry to know how the nano and micro structure of these materials is affected by the upscale in manufacturing necessary for the materials’ use in the nuclear industry. Until now, there were no tools capable of observing and mapping structures with nanometre resolution across macro sized areas, leading to inappropriate assumptions of sample homogeneity.
To assess the service life and durability of steel components it is necessary to include the evolution of their nano and micro-structures over the period of exposure of ageing in the constitutive life-prediction models. However, experimental information of precipitate parameters such as the average size and inter precipitate spacing are not often available and they have to be estimated by, for example, computer modelling.
We have developed the world’s fastest super resolution imaging tool called the high-speed atomic force microscope (HS-AFM), seen in Figure 1. The tool has nanometre lateral resolution and subatomic height resolution. Following a similar sample preparation protocol to many electron microscope imaging techniques, our new tool is able to image carbides and inclusions by mapping hardness induced topography.
The tool is able to use its high mapping rate to map areas with nanometre lateral resolution over areas millimetre in size in a matter of minutes or hours. A conventional AFM would take months or even years to collect similar datasets providing you with unparalleled sample statistics and feature mapping capability.
To fully understand how a material will age and eventually fail it is necessary to understand the fundamental nano and micro structures in the material; structures that are both present at the time of production and also secondary inclusions that develop with age.
Additionally, failure often presents itself at the nano and microscale prior to being visible at the macro scale. By developing the technology and processes necessary to characterise industrially relevant millimetre sized areas with nanometre resolution the manufacturing process of the materials may be held to the high standards required by the nuclear industry. In the case of materials with the deliberate inclusion of nanostructures it is important to have resolution to carry out quality control whilst also having the sample put through to characterise macro sized areas to check for material homogeneity which is central to the lifetime modelling of the plant component.
The award-winning tool (UK National Nuclear Laboratory 2015 innovation award) allows us to also observe dynamic nanoscale events such as corrosion at video rate at the nanoscale over areas microns in size under in vivo gaseous or liquid environments. All the 3D data is rendered in real-time and is recorded along with an optical microscope view of the surrounding surface. The data can be exported into a variety of industry standard formats to fit your workflow.
This technology has resulted in the creation of spinout company Bristol NanoDynamics that is commercialising this technology.