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MSE-302: Phase transformations

Ce cours est une introduction aux transformations de phases liquide-solide et solide-solide. Il aborde les aspects thermodynamiques et cristallographiques. Il traite principalement des matériaux métalliques, et établira des ponts vers les céramiques et la ...

Instructor

Cyril Cayron

1992-1995 Engineering School. Ecole des Mines de Nancy. 1994-1995 Master's degree in Materials Science (rank = 1st) 1995-1996 Military Service 1996-2000 PhD at EPFL-CIME. Precipitation in 6xxx alloys and composites. 2000-2014 Researcher, Engineer and Group leader on materials for new energies at CEA-Grenoble, France. 2012 Habilitation to supervise researches (HDR) 2014-now Senior Scientist at EPFL-LMTM Creator of the computer programs GenOVa and ARPGE (in Python). I currently work on crystallographic models of martensitic transformations and deformation twinning.

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Related concepts (14)

Martensite

Martensite is a very hard form of steel crystalline structure. It is named after German Adolf Martens. By analogy the term can also refer to any crystal structure that is formed by diffusionless transformation. Martensite is formed in carbon steels by the rapid cooling (quenching) of the austenite form of iron at such a high rate that carbon atoms do not have time to diffuse out of the crystal structure in large enough quantities to form cementite (Fe3C). Austenite is gamma-phase iron (γ-Fe), a solid solution of iron and alloying elements.

Diffusionless transformation

Diffusionless transformations, also referred to as displacive transformations, are solid-state changes in the crystal structure that do not rely on the diffusion of atoms over long distances. Instead, they occur due to coordinated shifts in atomic positions, where atoms move by a distance less than the span between neighboring atoms while maintaining their relative arrangement. An illustrative instance of this is the martensitic transformation observed in steel.

Bainite

Bainite is a plate-like microstructure that forms in steels at temperatures of 125–550 °C (depending on alloy content). First described by E. S. Davenport and Edgar Bain, it is one of the products that may form when austenite (the face-centered cubic crystal structure of iron) is cooled past a temperature where it is no longer thermodynamically stable with respect to ferrite, cementite, or ferrite and cementite. Davenport and Bain originally described the microstructure as being similar in appearance to tempered martensite.

Shape-memory alloy

In metallurgy, a shape-memory alloy (SMA) is an alloy that can be deformed when cold but returns to its pre-deformed ("remembered") shape when heated. It is also known in other names such as memory metal, memory alloy, smart metal, smart alloy, and muscle wire. The "memorized geometry" can be modified by fixating the desired geometry and subjecting it to a thermal treatment, for example a wire can be taught to memorize the shape of a coil spring.

Austenite

Austenite, also known as gamma-phase iron (γ-Fe), is a metallic, non-magnetic allotrope of iron or a solid solution of iron with an alloying element. In plain-carbon steel, austenite exists above the critical eutectoid temperature of 1000 K (727 °C); other alloys of steel have different eutectoid temperatures. The austenite allotrope is named after Sir William Chandler Roberts-Austen (1843–1902); it exists at room temperature in some stainless steels due to the presence of nickel stabilizing the austenite at lower temperatures.

Related lectures (19)

Martensitic Transformation: Metals and Alloys

Explores the martensitic transformation in metals and alloys, emphasizing the role of carbon atoms and contrasting with diffusive transformations.

Phase Transformations in Fe-C Alloys

Explores phase transformations in Fe-C alloys, emphasizing perlite and martensite formation and the role of carbon content.

Metallurgical Processes: Hardening and Maturation

Explores metallurgical hardening processes and microstructure evolution in metals and alloys through heat treatment.

Steel Heat Treatment: Transformation Diagrams

Covers the transformation diagrams of steel and the effects of alloying elements on the transformation process.

Martensitic Transformation: Structure and Properties