An Atom Probe Study of Kappa Carbide Precipitation and the Effect of Silicon Addition
Laura Bartlett,David C. Van Aken,Julia E. Medvedeva,Dieter Isheim,N. I. Medvedeva,Kai Song,Kai Song +6 more
Reads0
Chats0
TLDR
The influence of silicon on carbon precipitation in lightweight austenitic Fe-30Mn-9Al-(0.59-1.56)Si-0.5Mo cast steels was investigated utilizing transmission electron microscopy, 3D atom-probe tomography, X-ray diffraction, ab initio calculations, and thermodynamic modeling as mentioned in this paper.Abstract:
The influence of silicon on κ-carbide precipitation in lightweight austenitic Fe-30Mn-9Al-(0.59-1.56)Si-0.9C-0.5Mo cast steels was investigated utilizing transmission electron microscopy, 3D atom-probe tomography, X-ray diffraction, ab initio calculations, and thermodynamic modeling. Increasing the amount of silicon from 0.59 to 1.56 pct Si accelerated formation of the κ-carbide precipitates but did not increase the volume fraction. Silicon was shown to increase the activity of carbon in austenite and stabilize the κ-carbide at higher temperatures. Increasing the silicon from 0.59 to 1.56 pct increased the partitioning coefficient of carbon from 2.1 to 2.9 for steels aged 60 hours at 803 K (530 °C). The increase in strength during aging of Fe-Mn-Al-C steels was found to be a direct function of the increase in the concentration amplitude of carbon during spinodal decomposition. The predicted increase in the yield strength, as determined using a spinodal hardening mechanism, was calculated to be 120 MPa/wt pct Si for specimens aged at 803 K (530 °C) for 60 hours and this is in agreement with experimental results. Silicon was shown to partition to the austenite during aging and to slightly reduce the austenite lattice parameter. First-principles calculations show that the Si-C interaction is repulsive and this is the reason for enhanced carbon activity in austenite. The lattice parameter and thermodynamic stability of κ-carbide depend on the carbon stoichiometry and on which sublattice the silicon substitutes. Silicon was shown to favor vacancy ordering in κ-carbide due to a strong attractive Si-vacancy interaction. It was predicted that Si occupies the Fe sites in nonstoichiometric κ-carbide and the formation of Si-vacancy complexes increases the stability as well as the lattice parameter of κ-carbide. A comparison of how Si affects the enthalpy of formation for austenite and κ-carbide shows that the most energetically favorable position for silicon is in austenite, in agreement with the experimentally measured partitioning ratios.read more
Citations
More filters
Journal ArticleDOI
Current state of Fe-Mn-Al-C low density steels
TL;DR: A review on the physical metallurgy, processing strategies, strengthening mechanisms and mechanical properties of Fe-Mn-Al-C steels from the published literature over a period of many years, and suggests avenues for future applications of these alloys in the automotive sector as mentioned in this paper.
Journal ArticleDOI
Thermomechanical processing of advanced high strength steels
Jingwei Zhao,Zhengyi Jiang +1 more
TL;DR: A comprehensive review of recent progress in TMP of AHSSs, with focus on the processing-microstructure-property relationships of the processed AHSS, is provided in this paper.
Journal ArticleDOI
Strengthening and strain hardening mechanisms in a precipitation-hardened high-Mn lightweight steel
Mengji Yao,Emanuel David Welsch,Dirk Ponge,Seyed Masood Hafez Haghighat,Stefanie Sandlöbes,Stefanie Sandlöbes,Pyuck-Pa Choi,Michael Herbig,Ivan Bleskov,Tilmann Hickel,Marta Lipińska-Chwałek,Marta Lipińska-Chwałek,Pratheek Shanthraj,Christina Scheu,Stefan Zaefferer,Baptiste Gault,Dierk Raabe +16 more
TL;DR: In this article, the strengthening and strain hardening mechanisms in an aged high-Mn lightweight steel (Fe-30.4Mn-8Al-1.2C, wt.%) were studied by electron channeling contrast imaging (ECCI), transmission electron microscopy (TEM), atom probe tomography (APT) and correlative TEM/APT.
Journal ArticleDOI
A General Perspective of Fe-Mn-Al-C Steels
TL;DR: In this article, a review of Fe-Mn-al-C steels is presented to elucidate the complex relations between the chemical composition of the steel, the test temperature, the external loads and the processing parameters.
Journal ArticleDOI
A general perspective of Fe–Mn–Al–C steels
TL;DR: In this paper, a review of Fe-Mn-al-C steels is presented, focusing on the complex relationship between the chemical composition of the steel, the test temperature, the external loads, and the processing parameters.
References
More filters
Journal ArticleDOI
Generalized Gradient Approximation Made Simple
TL;DR: A simple derivation of a simple GGA is presented, in which all parameters (other than those in LSD) are fundamental constants, and only general features of the detailed construction underlying the Perdew-Wang 1991 (PW91) GGA are invoked.
Journal ArticleDOI
Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set.
Georg Kresse,Jürgen Furthmüller +1 more
TL;DR: An efficient scheme for calculating the Kohn-Sham ground state of metallic systems using pseudopotentials and a plane-wave basis set is presented and the application of Pulay's DIIS method to the iterative diagonalization of large matrices will be discussed.
Journal ArticleDOI
Norm-conserving and ultrasoft pseudopotentials for first-row and transition elements
Georg Kresse,Juergen Hafner +1 more
TL;DR: In this paper, the authors proposed a pseudowave function inside the cut-off radius with the concept of ultrasoft pseudopotentials introduced by Vanderbilt optimal compromise between transferability and plane-wave convergence.
Book
Handbook of Ternary Alloy Phase Diagrams
Pierre Villars,Alan Prince,博明 岡本 +2 more
TL;DR: The largest collection of ternary phase diagrams and related crystal structure data ever assembled can be found in this 10 volume set.
Journal ArticleDOI
Invited review article: Atom probe tomography.
Thomas F. Kelly,Michael K Miller +1 more
TL;DR: The technique of atom probe tomography is reviewed with an emphasis on illustrating what is possible with the technique both now and in the future, and how to fabricate suitable specimens from new classes of materials.
Related Papers (5)
Microstructures and Mechanical Properties of High-Strength Fe-Mn-Al-C Light-Weight TRIPLEX Steels
Georg Frommeyer,Udo Brüx +1 more