Research Profile - Department of Materials Science and Metallurgy ...

Harry Bhadeshia FREng FRS FNAE
Tata Steel Professor of Metallurgy
BSc City of London Polytechnic
PhD University of Cambridge
+44 (0) 1223 334301
hkdb@cam.ac.uk
www.msm.cam.ac.uk/phase-trans/index.html
Phase Transformations
There are so many phase changes in iron and its alloys
that it is possible to generate a seemingly infinite variety of
microstructures and properties. This complexity makes the
alloys versatile but at the same time difficult to understand and
design from first principles. Much of our energy is devoted to the
development of solid-state phase transformation theory, and its
experimental validation, in the hope of inventing new alloys and
processes.
Theory of transformations
We deal mostly with phase changes which are thermodynamically
of first order, i.e. they involve nucleation and growth with
well-defined mechanisms of transformations and particular
constraints to the achievement of equilibrium. In fact, most
useful microstructures are far from equilibrium so we build
kinetic theory to determine non-equilibrium states. There are
complications when many different transformations occur
together, complications which have stimulated new theory.
Finally, the microstructure must be related to properties which are
appreciated by technologists.
Mathematical models
We express the theory and empirical observations in the form
of computer models which can be used to greatly reduce the
vast number of parameters that have to be controlled during the
creation of new alloys and processes. We also produce courses,
books and algorithms in addition to research papers to help
spread the word about this thriving science of materials.
H Matsuda & HKDH Bhadeshia, “Kinetics of the bainite transformation”
Proc. Roy. Soc. (London) A 460, 1710–1722 (2004).
HKDH Bhadeshia, “Large chunks of very strong steel” Mater. Sci. Technol.
21, 1293–1302 (2005).
S Yamasaki & HKDH Bhadeshia, “M 4
C 3
precipitation in Fe-C-Mo-V steels
and relationship to hydrogen trapping” Proc. Roy. Soc. (London) A 462,
2315–2330 (2006).
S Chatterjee, HS Wang, JR Yang & HKDH Bhadeshia, “Mechanical
stabilisation of austenite”, Mater. Sci. Technol. 22, 645–649 (2006).
Bulk nanostructured steel with a scale finer than carbon
nanotubes, now produced in tonnage quantities
Research Profile 7