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Lecture

Deformation and Rupture of Materials

In course

MSE-310: Deformation of materials

Présentation des mécanismes de déformation des matériaux inorganiques: élasticité, plasticité, fluage. ...

Description

This lecture covers the deformation and rupture of materials at low temperature, focusing on crystallographic relationships, mechanical twins, and twinning mechanisms. It discusses the creation of twins from partial dislocations, the energy considerations involved, and the critical stages of twin germination. The instructor explains the accommodation of different types of deformations, the role of dislocations in twinning, and the thermally activated mechanisms. Various mechanical twin geometries and their implications on crystal structures are also explored.

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Instructor

Roland Logé

Roland Logé is an associate professor at EPFL, with a primary affiliation to the Materials Institute, and a secondary affiliation to the Microengineering Institute. After graduating in 1994 at UCL (Belgium) in Materials Engineering, he earned a Master of Science in Mechanics in 1995, at UCSB Santa Barbara (USA). He received his PhD at Mines Paristech-CEMEF (France) in 1999, where he specialized in metal forming and associated microstructure evolutions. After a postdoc at Cornell University (USA) between 1999 and 2001, he entered CNRS in France. In 2008, he was awarded the ALCAN prize from the French Academy of Sciences, together with Yvan Chastel. In 2009 he became head of the Metallurgy-Structure-Rheology research group at CEMEF. In 2011, he launched a “Groupement de Recherche” (GDR), funded by CNRS, networking most of the researchers in France involved in recrystallization and grain growth. In 2013, he became Research Director at CNRS. In March 2014 he joined EPFL as the head of the Laboratory of Thermomechanical Metallurgy.

Official source

Related concepts (23)

Deformation (engineering)

In engineering, deformation refers to the change in size or shape of an object. Displacements are the absolute change in position of a point on the object. Deflection is the relative change in external displacements on an object. Strain is the relative internal change in shape of an infinitesimally small cube of material and can be expressed as a non-dimensional change in length or angle of distortion of the cube. Strains are related to the forces acting on the cube, which are known as stress, by a stress-strain curve.

Deformation (physics)

In physics and continuum mechanics, deformation is the transformation of a body from a reference configuration to a current configuration. A configuration is a set containing the positions of all particles of the body. A deformation can occur because of external loads, intrinsic activity (e.g. muscle contraction), body forces (such as gravity or electromagnetic forces), or changes in temperature, moisture content, or chemical reactions, etc. Strain is related to deformation in terms of relative displacement of particles in the body that excludes rigid-body motions.

Crystal twinning

Crystal twinning occurs when two or more adjacent crystals of the same mineral are oriented so that they share some of the same crystal lattice points in a symmetrical manner. The result is an intergrowth of two separate crystals that are tightly bonded to each other. The surface along which the lattice points are shared in twinned crystals is called a composition surface or twin plane. Crystallographers classify twinned crystals by a number of twin laws. These twin laws are specific to the crystal structure.

Materials science

Materials science is an interdisciplinary field of researching and discovering materials. Materials engineering is an engineering field of finding uses for materials in other fields and industries. The intellectual origins of materials science stem from the Age of Enlightenment, when researchers began to use analytical thinking from chemistry, physics, and engineering to understand ancient, phenomenological observations in metallurgy and mineralogy. Materials science still incorporates elements of physics, chemistry, and engineering.

Material

Material is a substance or mixture of substances that constitutes an object. Materials can be pure or impure, living or non-living matter. Materials can be classified on the basis of their physical and chemical properties, or on their geological origin or biological function. Materials science is the study of materials, their properties and their applications. Raw materials can be processed in different ways to influence their properties, by purification, shaping or the introduction of other materials.

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