Leo Kestens

“Engineering of 3D microstructures in metals: bridging ten length scales of functionality”

Leo Kestens was born on June 26th 1964 in Aalst, Belgium. More than twenty years ago he has graduated as an Engineer in Physics from Ghent University in Belgium. From Ghent he moved to Leuven where he has made the switch from physics to materials science and obtained his PhD in 1994 with a dissertation on the role of crystallographic textures in electrical steels which are used as magnetic flux carriers in a wide variety of applications. After his promotion he has continued his research in the field of steel metallurgy, first as a postdoc in the group of Prof. John J. Jonas at McGill University in Montreal and afterwards at the Centre for Research in Metallurgy (CRM) which is the collective research centre of the Benelux steel industry. In 1998 he returned to Ghent University where he has started his own research group on the crystallographic aspects of physical metallurgy and since 2005 he was appointed at TU-Delft where he holds the chair on Microstructure Control in Metals.

The research that he is carrying out with his group is entirely focused on the microstructure of metals. To a certain extent, the goal of this work can be compared to the attempt of unveiling the DNA code of the (human) genome. On the basis of ab-initio principles materials scientists know that all macroscopic materials owe their properties to their microstructural features which can be revealed with various microscopes with resolutions that vary from a few microns to less than 1 Å. Whereas physicists consider idealized matter (i.e. systems which are strongly conditioned by severe boundary and initial values) materials engineers rather work with matter as it is used in the real world. Such materials, which in our society are very often available as commodity goods such as steel, aluminium or copper, exhibit an amazing abundance of complex microstructural features such as grain boundaries, crystal orientations, different crystal phases and nano-sized particles. In a very broad way all of these microstructural features can be considered as defects of the perfect crystal lattice. Hence the mission of the materials science engineer is to control and design the structure of these lattice defects so as to obtain the desired macroscopic properties. Most often it is the complexity of the interactions between such defects which constitutes the most challenging obstacle in reaching this goal. One simple example may illustrate this complexity: although the stress field around one single dislocation is precisely known as well as the interaction behavior between a limited number of dislocations, material scientists still struggle today with the complex (but organised) patterns that arise when huge numbers of dislocations start to interact. Brutal computing force will not be sufficient to solve this problem as in the next foreseeable future computers will not be powerful enough to take into account all of the (non-linear) interactions. Hence, clever abstractions are required which extract the essential state variables from the microstructure under consideration and which are of relevance to the property of interest. This can only be obtained by a concerted effort of computational modelling in combination with advanced experimental observation of microstructures.