Propiedades mecánicas

The aim of the line is the study of those plastic events occurring at surfaces, specially during very incipient plasticity. We focus in the possible role of surface defects acting as centers where dislocations might nucleate heterogeneously under the application of external stress.


Recent related publications:


Surface defects and their influence on surface properties

J. Phys.: Condens. Matter 25 484008 (2013)

O. Rodríguez de la Fuente, M.A. González-Barrio, V. Navarro, B.M. Pabón, I. Palacio and A. Mascaraque


Moplecular dynamics modeling and simulation of void growth in two dimensions

Modelling and Simulation in Materials Science and Engineering 21, 075010 (2013)

H.-J. Chang, J. Segurado, O. Rodríguez de la Fuente, B.M. Pabón and J. LLorca




in collaboration with:

Javier Segurado

Hyung-Jun Chang

Javier LLorca

from the Materials Science Department, Escuela Superior de Ingenierios de Caminos, Canales y Puertos, Universidad Politécnica de Madrid.


The nucleation, growth and coalescence of voids in the bulk are all processes usually involved in the ductile failure of metals. Several mechanisms are responsible for the evolution of the previous phenomena, and size effects are present, specially in submicron voids. We use 2D atomistic simulations to study the different processes taking place during void growth under the application of external stresses.

It is relatively well known that, at room temperature, there exists dislocation activity associated to void growth. Doubts arise when questioning about the precise plastic mechanisms which make the void grow. A reasonable mechanism which has been considered before is the emission of dislocations from sources in the bulk and their subsequent absorption by the voids: when a dislocation ends up in the surface of a void, it disappears and the void volume is enlarged. However, this mechanism does not seem to be very active when the voids are sufficiently small.

In the work we are involved in we consider another possible void growth mechanism: the emission of dislocation from the surface of the voids. We study this possibility in a 2D framework, using molecular dynamics.



Scheme of the contact between real surfaces

Putting two solids together is rather like turning Switzerland upside down and standing it on Austria. F.P. Bowden, Cambridge University.


When two real (rough) surfaces touch each other, mechanical contact usually takes place through the existing protrusions or asperities existing in both sides. Thus, the real contact surface is lower than the apparent contact surface. High loads are then concentrated in these protrusions, which are indeed formed, at the atomic scale, by surface defects (mainly steps).

nanoindentation simulation

Dislocation half-loops nucleated at surface steps during an atomistic simulation of a nanoindentation process. This is a sub-surface ima