Confined chemical and structural states at dislocations in Fe-9wt%Mn steels: A correlative TEM-atom probe study combined with multiscale modelling

Silva, Alisson Kwiatkowski da; Leyson, Gerard; Kuzmina, Margarita; Ponge, Dirk; Herbig, Michael; Sandlöbes, Stefanie; Gault, Baptiste; Neugebauer, Jörg; Raabe, Dierk

doi:10.1016/j.actamat.2016.11.013

Cited by 84 publications

(47 citation statements)

References 67 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This enrichment is due to segregation of solutes at dislocations, which has been previously reported in APT studies conducted on various materials [24][25][26] and has been unambiguously confirmed by correlative transmission electron microscopy (TEM) and APT analysis. [27,28] A cylindrical region of interest perpendicular to the dislocation, labeled as arrow #1 in Figure 6 Similar observations regarding the segregation and diffusion of chromium and cobalt along dislocations were revealed by APT for two other different nickel-based superalloys. [29] The segregation of chromium and cobalt to dislocations was therein assumed to result in local chemical inhomogeneities and drain these elements from the c matrix.…”

Section: Dissolution Of C¢ Precipitatessupporting

confidence: 69%

The Role of Oxidized Carbides on Thermal-Mechanical Performance of Polycrystalline Superalloys

Kontis

Segersäll

et al. 2018

Metall Mater Trans A

View full text Add to dashboard Cite

Oxidized MC carbides which act as main crack initiation sites in a polycrystalline superalloy under thermal-mechanical fatigue (TMF) conditions at 850°C were studied. Microstructural observations in the TMF tested specimens were compared to findings from bulk samples exposed isothermally in air at 850°C for 30 hours in the absence of any external applied load. Carbides were found to oxidize rapidly after exposure at 850°C for 30 hours resulting in surface eruptions corresponding to oxidation products, from where micro-cracks initiated. Plastic deformation due to volume expansion of the often porous oxidized carbides led to high dislocation densities in the adjacent matrix as revealed by controlled electron channeling contrast imaging. The high dislocation density facilitated the dissolution kinetics of c¢ precipitates by segregation and diffusion of chromium and cobalt along the dislocations via pipe diffusion, resulting in the formation of soft recrystallized grains. Atom probe tomography revealed substantial compositional differences between the recrystallized grains and the adjacent undeformed c matrix. Similar observations were made for the TMF tested alloy. Our observations provide new insights into the true detrimental role of oxidized MC carbides on the crack initiation performance of polycrystalline superalloys under TMF.

show abstract

Section: Dissolution Of C¢ Precipitatessupporting

confidence: 69%

The Role of Oxidized Carbides on Thermal-Mechanical Performance of Polycrystalline Superalloys

Kontis

Segersäll

et al. 2018

Metall Mater Trans A

View full text Add to dashboard Cite

show abstract

“…A detailed study of the segregation of Mn to linear defects in a model Fe9Mn binary alloy by a combination of APT and transmission electron microscopy, led to the possible detection of confined phases, nucleated at dislocations, that are not isostructural with the host matrix 56,73 . These are akin to the concept of complexions, a term that describes the interfacial state in local equilibrium with its abutting phase(s) 74,75 One of the most interesting aspects of this study is the reasoning that there is a strong interplay between the local structure and the local composition of a specific microstructural feature.…”

Section: Phase Nucleation At Crystalline Defectsmentioning

confidence: 99%

Interfaces and defect composition at the near-atomic scale through atom probe tomography investigations

et al. 2018

View full text Add to dashboard Cite

show abstract

“…The microstructure was characterized by high-resolution electron backscatter diffraction (EBSD). Chemical gradients between austenite and martensite for representative samples were investigated by atom probe tomography (APT) [19,22,[33][34][35]. The experimental data were compared with thermokinetic and thermodynamic simulations, using DICTRA and Thermo-Calc, respectively.…”

Section: Introductionmentioning

confidence: 99%

Martensite to austenite reversion in a high-Mn steel: Partitioning-dependent two-stage kinetics revealed by atom probe tomography, in-situ magnetic measurements and simulation

et al. 2019

Self Cite

View full text Add to dashboard Cite

Austenite () reversion in a cold-rolled 17.6 wt.% Mn steel was tracked by means of dilatometry and in-situ magnetic measurements during slow continuous annealing. A splitting of the -reversion into two stages was observed to be a result of strong elemental partitioning between  and '-martensite during the low temperature stage between 390 and 575ºC. Atom probe tomography (APT) results enable the characterization of the Mn-enriched reversed- and the Mn-depleted remaining 'martensite. Because of its lower Mn content, the reversion of the remaining 'martensite into austenite takes place at a higher temperature range between 600 and 685ºC. APT results agree with partitioning predictions made by thermo-kinetic simulations of the continuous annealing process. The critical composition for nucleation was predicted by thermodynamic calculations (Thermo-Calc) and a good agreement was found with the APT data. Additional thermo-kinetic simulations were conducted to evaluate partitioning-governed -growth during isothermal annealing at 500°C and 600°C. Si partitioning to  was predicted by DICTRA and confirmed by APT. Si accumulates near the moving interface during -growth and homogenizes over time. We used the chemical composition of the remaining '-martensite from APT data to calculate its Curie temperature (T Curie) and found good agreement with magnetic measurements. These results indicate that elemental partitioning strongly influences not only -reversion but also the T Curie of this steel. The results are important to better understand the thermodynamics and kinetics of austenite reversion for a wide range of Mn containing steels and its effect on magnetic properties.

show abstract

Confined chemical and structural states at dislocations in Fe-9wt%Mn steels: A correlative TEM-atom probe study combined with multiscale modelling

Cited by 84 publications

References 67 publications

The Role of Oxidized Carbides on Thermal-Mechanical Performance of Polycrystalline Superalloys

The Role of Oxidized Carbides on Thermal-Mechanical Performance of Polycrystalline Superalloys

Interfaces and defect composition at the near-atomic scale through atom probe tomography investigations

Martensite to austenite reversion in a high-Mn steel: Partitioning-dependent two-stage kinetics revealed by atom probe tomography, in-situ magnetic measurements and simulation

Contact Info

Product

Resources

About