CuCrZr alloys possess a unique combination of high thermal conductivity, corrosion resistance, and good mechanical properties making them well suited to application in advanced heat exchange devices. They also contain only low activation elements so they are hugely attractive in the highly demanding environments seen in divertor modules in many designs for fusion power reactors. Here, as well as most other applications, there are both sustained loading and superimposed fluctuations. This means both creep and creep-fatigue interactions are crucial for component lifing, but are not well understood.
This project will build on the previous H2020 Strength-ABLE programme that characterized effects of heat treatments on microstructures and monotonic tensile properties of CuCrZr. We will concentrate on the ITER grade, peak aged heat treatment condition (treatment B in SDC-IC), but move to more complex loading regimes that are better matched to service conditions. Initial testing will look a primary-secondary creep transitions under sustained loading, along with capturing Bauschinger effects on flow stresses after load reversals (tension to compression, or sense of shear direction). This will build towards full cyclic testing.
Initial testing will look a primary-secondary creep transitions under sustained loading, along with capturing Bauschinger effects on flow stresses after load reversals (tension to compression, or sense of shear direction). This will build towards full cyclic testing. Ex-situ testing with optical digital image correlation will be used to construct mechanical data from a wide test matrix. This will be complemented detailed localized measurements from interrupted tests that will use AFM, HR-EBSD, and if needed TKD to understand where hot spots in strain and stress accumulate within the microstructure. We will also down select to test conditions for in situ testing in the SEM that will use established HR-DIC methods to study the local evolution of strain within slip bands under creep and creep-fatigue loading.
Outputs from the testing programme will be captured in advanced crystal plasticity FEA simulations via interaction with the Design by Fundamentals (DbF) project for STEP. This will aim to match overall isotropic and kinematic hardening response of the system. We will also explore the ability to capture the statistical trends at the local level, i.e. in the number of slip bands formed in different conditions and the distributions of strains between them.
The project will involve significant interaction with collaborators at CCFE.
