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Nanoscale phase transformations at martensite interfaces

Date: 07.05.2013
Time: 03:50 p.m.
Place: ICAMS² 2013, International Colloquium on Advanced Materials Simulation, Bochum, Germany

Dirk Ponge, Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
Julio Millán, Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
Stefanie Sandlöbes, Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
Pyuck-Pa Choi, Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
Hamid Assadi, Tarbiat Modares University, Teheran, Iran
Dierk Raabe, Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany

We observe self organized martensite-austenite nanostructures in steels. This is achieved through selective phase transformation (martensite-to-austenite reversion in this case) at martensite interfaces that are decorated by segregating solutes, which locally reduce the martensite-to-austenite transformation temperature compared to the surrounding bulk material. The analysis is conducted using joint TEM and atom probe tomography.The phenomena are discussed in terms of the adsorption isotherm (interface segregation) in conjunction with classical nucleation theory (phase transformation) and a phase field model that predicts phase transformation at segregation decorated grain boundaries. The analysis shows that strong interface segregation of austenite stabilizing elements and the release of elastic stresses from the host martensite can generally promote phase transformation at martensite grain boundaries. The phenomenon enables the design of ductile and tough martensite.

Supporting information:

abstract_raabe.pdf
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