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Thermodynamic Modeling of the Al-Mn-C system

Thursday (29.09.2016)
09:45 - 10:00
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Excellent combinations of strength and ductility paired with the possible weight reduction motivates the research of high manganese TWIP or multi-phase steels. The development of alloying concepts to achieve the goals required for safety relevant applications in e.g. automotive applications for these steels depend on finely adjustable material properties by thermo-mechanical treatment and thus demand accurate thermodynamical description for efficient theoretical alloy design. A possible design concept for such steels is the formation of finely dispersed intermetallic phases, such as the κ phase (structure type E21, (Fe,Mn)3AlC).

As a sub-system of the quaternary Fe-Mn-Al-C, the Al-Mn-C system is fundamental for the design of high manganese and aluminium alloys. New experimental data by Fartushna et al. give new insights into the composition range and solubility of Al-Mn-C alloys at temperatures above 1000 °C where previously no data was available. Both liquidus and solidus temperatures along with isothermal sections at 1100 °C and 1200 °C have been recorded. It is shown that the κ phase melts congruently and has a wide field of primary crystallization. In addition, previously determined isothermal sections at 700 °C and 1000 °C were used for the modeling [1].

In the work presented, the Al-Mn-C system is thermodynamically modeled using the new experimental data. The results about the κ phase indicate that previous modeling as a stoichiometric compound [2] is not suitable given the large homogeneous region. Therefore, a four sub-lattice model of an ordered fcc structure has been implemented to allow for non-stoichiometry and is presented and compared to previous models.

[1] J.C. Schuster, H. Nowotny, Z. Metallkd. 72 (1981) 63–66.

[2] D. Connetable et al., CALPHAD 35 (2011) 588.


Florian Tang
RWTH Aachen University
Additional Authors:
  • Dr. Bengt Hallstedt
    RWTH Aachen University
  • Iuliia Fartushna
  • Irina Bajenova
  • Dr. Alexandra Khvan


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