X-Ray Tomography

The understanding of materials has gradually increased aided by the development of methods that provide as complete and unbiased description of microstructure as possible. X-ray computed tomography (XCT) is a non-destructive imaging technique that provides information on the three-dimensional (3D) structure of a material. It is based on the collection of a series of radiographies on an X-ray detector at different angular positions. Absorption contrast X-ray computed tomography is probably the most well-known 3D X-ray imaging method. In this mode it is possible to detect differences between x-ray absorption coefficients of different phases, inclusions, defects, damage, etc. provided they are different enough. This technique has been traditionally used in medicine, but it became increasingly interesting for material science application with the improvement in spatial and temporal resolution for laboratory devices.

From the 3D microstructure, quantitative information in three dimensions can be retrieved using methodologies based on image analysis techniques. 3D data provides access to some very important geometric and topological quantities such us size, shape, orientation distribution of individual features and that of their local neighbourhoods, connectivity between features and network, composition, etc.

The non-destructive characteristic of X-rays applied to material science provides an interesting approach to XCT which is 4D tomography. This refers to the possibility to perform a repeated series of 3D tomographies at sequential time lapses, providing information about the microstructure evolution and with the possibility to be coupled also with in-situ devices (tensile/compression rigs, temperature application, fatigue, etc.). In material science and experimental mechanics, the evolution of microstructure can be very important during manufacturing, service life and in understanding failure mechanisms.

Another advantage of X-ray imaging is it versatility which allows its application in several scientific and industrial fields, ranging from composite materials, cements, metals and alloys, bio-materials, plants, etc.

In our group we make use of laboratory and synchrotron X-ray tomography to characterize a wide range of materials, such as polymer composites, metals and alloys, bio-materials, cements, etc., in 2D (radiography), 3D (tomography) and 4D (4D-tomography). Special attention is given to in-situ testing of different kinds, such us the study of damage mechanism at room and high temperatures, understanding material processing kinetics (in-situ infiltration, in-situ solidification), and combination with other techniques, e.g. X-ray diffraction (XRD). However, extracting relevant information from their microstructure often requires the development of image analysis tools for a proper quantitative analysis in an automated manner. We also combine this special characterization tool with other techniques available at IMDEA Materials Institute for correlative studies and proper understanding of the materials and processes.

Our research lines are:

4D tomography: damage development and evolution in structural materials, e.g. fiber reinforced composites, light metal alloys, steels, etc. by means of in-situ or sequential testing at room and high temperature. Some examples are tensile, fatigue, three point bending, creep
Optimization of Out-of-Autoclave Processing of Composites (AROOA & DEFCOM project).
Effect of the casting defects in Mg alloys and Ni-based superalloys (XMART project).
Correlation between 3D microstructure and mechanical properties of materials.
In-situ XCT infiltration of fibers by vacuum assisted resin transfer molding process

X-Ray Tomography

4D tomography

Optimization of OoA processing of composites

Effects of casting defects