Uploaded December 2025 | Updated September 2026, 2 weeks ago
This video consists of excerpts from the Edward De Mille Campbell Memorial Lecture, where H.K.D.H. Bhadeshia. The publication itself is available in Metallurgical and Materials Transactions A:
doi.org/10.1007/s11661-025-08017-7
The video summarises a definitive argument regarding the nature of the bainite transformation in steel alloys. The central assertion is that this transformation is fundamentally a displacive, shear-based mechanism and is definitively halted when the concentration of carbon in the austenite reaches the T0 thermodynamic limit. Extensive experimental results, including high-resolution atom-probe studies, are cited to demonstrate that the reaction occurs without the partitioning of substitutional solutes, rejecting alternative models like "negligible partitioning local equilibrium." The analysis confirms that the resultant bainitic ferrite contains supersaturated carbon due to the associated lattice strain, which is now understood quantitatively. This refined quantitative understanding has been successfully applied to commercial materials development, notably the creation of the world’s first bulk nanostructured steel. The author concludes that the phenomena associated with Widmanstätten ferrite, bainite, and martensite can now be explained using a unified, rigorous theory.
phase-trans.msm.cam.ac.uk/2025/Campbell.html
phase-trans.msm.cam.ac.uk/bainite_NN.html
This video consists of excerpts from the Edward De Mille Campbell Memorial Lecture, where H.K.D.H. Bhadeshia. The publication itself is available in Metallurgical and Materials Transactions A:
doi.org/10.1007/s11661-025-08017-7
The video summarises a definitive argument regarding the nature of the bainite transformation in steel alloys. The central assertion is that this transformation is fundamentally a displacive, shear-based mechanism and is definitively halted when the concentration of carbon in the austenite reaches the T0 thermodynamic limit. Extensive experimental results, including high-resolution atom-probe studies, are cited to demonstrate that the reaction occurs without the partitioning of substitutional solutes, rejecting alternative models like "negligible partitioning local equilibrium." The analysis confirms that the resultant bainitic ferrite contains supersaturated carbon due to the associated lattice strain, which is now understood quantitatively. This refined quantitative understanding has been successfully applied to commercial materials development, notably the creation of the world’s first bulk nanostructured steel. The author concludes that the phenomena associated with Widmanstätten ferrite, bainite, and martensite can now be explained using a unified, rigorous theory.
phase-trans.msm.cam.ac.uk/2025/Campbell.html
phase-trans.msm.cam.ac.uk/bainite_NN.html
