This project examined how early-stage phase transformations influence the microstructure and service performance of duplex stainless steels, materials widely used in demanding environments where strength, corrosion resistance, and durability are critical. The research focused on understanding how processing conditions—particularly intermediate heat treatments—affect phase separation, embrittlement, and the formation of detrimental intermetallic phases, with the aim of extending component lifetime and supporting more sustainable material use.
In situ neutron scattering techniques played a central role in the study. Small-angle neutron scattering (SANS) was used to follow the nanoscale evolution of phase separation in ferrite during thermal ageing, with refined analysis methods developed to capture the very earliest stages of decomposition. This approach enabled quantification of how intermediate heat treatments slowed phase separation kinetics. In parallel, in situ neutron diffraction was applied to investigate the formation kinetics of the brittle sigma phase in both model and commercial alloys, while neutron total scattering and pair distribution function (PDF) analysis were used to probe local structural changes and assess the impact of crystallographic texture on data interpretation.
Together, the results clarified how targeted thermal treatments can delay embrittlement while highlighting the limits of predictive modelling for complex phase transformations. The work established neutron scattering as a powerful tool for resolving nanoscale transformation mechanisms in bulk engineering alloys and provided knowledge that supports the design of more durable, reliable stainless steels for industrial applications.