Optical Measurements,Modeling and Metrology

3D structures of alloys and nanoparticles observed by electron tomography

ABSTRACT 3D structures of bulk alloys and nanoparticles have been studied by means of electron tomography using scanning transmission electron microscopy (STEM). In the case of nanoparticles of Fe-Pd alloy, particle size, shape, and locations were reconstructed by weighted backprojection (WBP), as well as by simultaneous iterative reconstruction technique (SIRT). We have also estimated the […]

Damage characterization in Dual-Phase steels using X-ray tomography

ABSTRACT In-situ tensile tests have been carried out during X-ray microtomography imaging of dual-phase steels. Void nucleation has been quantified as a function of strain and triaxiality using the obtained 3D images. The Argon’s criterion of decohesion has then been used in a model for nucleation in the case where martensite plays the role of […]

In-situ synchrotron-radiation computed laminography observation of ductile fracture

Synchrotron-radiation computed laminography (SRCL) allows for imaging at high resolution 1 ^m) and in three dimensions objects that are thin (~ 1 mm) but extended laterally in two dimensions. This represents a major advantage over computed tomography in terms of loading conditions that can typically only investigate samples elongated in one direction. Here SRCL is […]

Understanding the mechanical behaviour of a high manganese TWIP steel by the means of in situ 3D X ray tomography

ABSTRACT The high manganese TWIP (twinning induced plasticity) steels exhibit very high mechanical properties compared to others grades. Indeed they have a mechanical strength that can attain 1.5 GPa and fracture strain that can go up to 60%. However the governing damage mechanisms that maximize their ductility are not well understood. To have a better […]

Mechanical properties of Monofilament entangled materials

ABSTRACT A new type of architectured materials, namely « monofilament entangled materials », were studied in order to have a better understanding of their behavior under compressive loading and damping. The materials studied in this paper were made of an entanglement of a single steel wire. Their complex internal architecture was investigated using X-ray computed […]

Characterisation of mechanical properties of cellular ceramic materials using X-Ray computed tomography

Abstract Carbon foams are refractory cellular materials. The material exhibits an open porosity with a tridimensional architecture offering multifunctional properties. These properties can ever be tailored threw post processing in order to use the material in many fields such as energy (fuel cell) or transport (shock absorber). For all applications, the knowledge of the mechanical […]

Multiaxial stress state assessed by 3D X-Ray tomography on semi-crystalline polymers

ABSTRACT This work aims at linking the microstructural evolution of semi-crystalline polymers to the macroscopic material behaviour under multiaxial stress state. Tensile tests on notched round bars, interrupted after different stages of deformation before failure, were supposed to have undergone various states of stress in the vicinity of the net cross-section. They were examined using […]

Effect of Porosity on the Fatigue Life of a Cast Al Alloy

ABSTRACT A methodology has been developed to investigate the causes of fatigue fracture in the pressure-cast aluminium alloy Al Si9 Cu3 (Fe). Several samples have been tested. In each case porosity was the primary cause for failure. 3D tomographic images of the samples porosity at the initial state have been used as a basis for […]

Fatigue mechanisms of brazed Al-Mn alloys used in heat exchangers

ABSTRACT The ratio of aluminium alloys used in the automotive industry tends to increase as a consequence of the enforcement of tougher environmental regulation (minimization of vehicles weight). For example, thanks to their good thermal, corrosion and mechanical properties, aluminium alloys have steadily replaced copper alloys and brass for manufacturing heat exchangers in cars or […]

Three Dimensional Confocal Microscopy Study of Boundaries between Colloidal Crystals

ABSTRACT Colloidal crystals were grown on flat or patterned glass slides. The structure of the grains and their defects was first visualized by 3D confocal microscopy and then characterized using simple geometric measurements. Crystals grown on a flat surface maintained a layered structure induced by the closed-packed planes. In the case of the [110] E5 […]

← Previous Entries