A theoretical investigation of orientation relationships and transformation strains in steels

Koumatos, Konstantinos; Muehlemann, Anton

doi:10.1107/s2053273316020350

Cited by 57 publications

(36 citation statements)

References 21 publications

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“…Discrete plots from the FCC and BCC phases shown in Fig. 2(e,f) respectively, reveal that {011} BCC // {111} FCC and <001> BCC // <011> FCC, indicating a Nishiyama-Wasserman orientation relationship between the lamellae 30 .…”

Section: (A)mentioning

confidence: 97%

Hierarchical Eutectoid Nano-lamellar Decomposition in an Al0.3CoFeNi Complex Concentrated Alloy

Dasari

Gwalani

Jagetia

et al. 2020

Sci Rep

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this paper reports a novel eutectoid nano-lamellar (fcc + L1 2 )/(Bcc + B2) microstructure that has been discovered in a relatively simple Al 0.3 cofeni high entropy alloy (HeA) or complex concentrated alloy (CCA). This novel eutectoid nano-lamellar microstructure presumably results from the complex interplay between Al-mediated lattice distortion (due to its larger atomic radius) in a face-centered cubic (FCC) CoFeNi solid solution, and a chemical ordering tendency leading to precipitation of ordered phases such as L1 2 and B2. This eutectoid microstructure is a result of solid-state decomposition of the FCC matrix and therefore distinct from the commonly reported eutectic microstructure in HEAs which results from solidification. This novel nano-lamellar microstructure exhibits a tensile yield strength of 1074 MPa with a reasonable ductility of 8%. The same alloy can be tuned to form a more damagetolerant fcc + B2 microstructure, retaining high tensile yield stress (~900 MPa) with appreciable tensile ductility (>20%), via annealing at 700 °C. Such tunability of microstructures with dramatically different mechanical properties can be effectively engineered in the same CCA, by exploiting the complex interplay between ordering tendencies and lattice distortion.High entropy alloys (HEAs), also referred to as complex concentrated alloys (CCAs) or multi-principal element alloys (MPEAs), offer the ability to design novel microstructures that have not been possible with conventional alloys. In recent times, there has been a rapid increase in papers reporting such novel microstructures with excellent mechanical properties 1-7 . However, there are still many unanswered questions related to the influence of composition and processing on the phase stability, transformation pathways, and microstructural evolution in these complex alloys. In an effort to understand solid solution strengthening in HEAs, the room temperature and high temperature tensile properties of solutionized ternary and quaternary subsets of CoCrFeNiMn (Cantor alloy), CoCrFeNi, CoFeNi, CoCrNi etc. were studied by Wu et al. 8 . They reported that yield strength may not be necessarily a simple function of number of elements but it is a complex relation. Among the systems investigated, CoCrNi had the highest yield strengths overall, at tested temperatures. Since then, numerous investigations have been carried out on this alloy to understand its mechanical behavior 9,10 . Their work also shows that FCC single phase solid solutions in HEAs perform better than conventional FCC single phase alloys and thus strengthening the single phase HEAs with precipitation is anticipated to produce alloys with excellent mechanical properties.Addition of Al to 3d transition element-based face-centered cubic (FCC) high entropy alloys (HEAs), typically containing the elements Co, Cr, Fe, and Ni, results in substantial changes in their microstructure and mechanical properties. This is due to the tendency of Al to effectively introduce an ordering tendency within the FCC matrix, f...

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Section: (A)mentioning

confidence: 97%

Hierarchical Eutectoid Nano-lamellar Decomposition in an Al0.3CoFeNi Complex Concentrated Alloy

Dasari

Gwalani

Jagetia

et al. 2020

Sci Rep

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“…The base rotation matrix (OR 1 ) of each ideal relationship was calculated from the Euler angles defined for the transformation !, shown in Table 1. In order to obtain all the rotational matrices of each OR, we used the group of 24 rotations (P i ) that describes the symmetry of cubic crystals, summarized by Koumatos & Muehlemann (2017). Equation (1) was used to perform these calculations:…”

Section: Rotation Matrices Ideal Orientations and Misorientation Angmentioning

confidence: 99%

Crystallographic orientation relationships in the α→γ′ martensitic transformation in an Fe–Mn–Al–Ni system

et al. 2018

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The Fe 43.5 Mn 34 Al 15 Ni 7.5 (at.%) alloy exhibits outstanding pseudoelastic behaviour over a wide range of temperatures. This alloy undergoes an unusual martensitic transformation from a disordered body-centred cubic () parent phase to a face-centred cubic ( 0 ) product phase. In the present work, the orientations of the parent and product phases for quenched samples were analysed by electron backscatter diffraction. Bain, Kurdjumow-Sachs, Pitsch, Nishiyama-Wassermann and Greninger-Troiano orientation relationships between the parent and product phases were compared with experimental results. The Pitsch relationship appears to be the most suitable to describe the ! 0 martensitic transformation. This result provides experimental support to the dislocation-based heterogeneous Bogers-Burgers type transformation mechanism. No indications of variant selection were detected in the thermally activated transformations.

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“…Simultaneous EBSD and EDS acquisition enables in-depth offline analysis of the region of interest, and we show results in Figure 2. We observe a strong orientation relationship in this field of view [18], which can be reconstructed using the Kudjimov -Sachs orientation relationship using the MTEX tool developed by Nyyssonen et al [19] (this reconstruction is not shown here). This can be observed not only within crystal orientation maps (shown colour coded with inverse pole figure colour with respect to the X and Z axes) as well as in the pole figure plots of the BCC and FCC phases.…”

Section: Bse Imaging In Reflection Modementioning

confidence: 58%

Space rocks and optimising scanning electron channelling contrast

Britton

Goran

Tong

2018

Materials Characterization

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Graphical Abstract AbstractForescatter electron imaging is a popular microscopy technique, especially for scanning electron microscopes equipped with an electron backscatter diffraction detector. In principal, this method enables qualitative imaging of microstructure but quantitative assessment can be limited due to limited information about the contrast afforded. In this work, we explore forescatter electron imaging and demonstrate that imaging can be optimised for topographic, phase, and subtle orientation contrast imaging through appropriate sample and detector positioning. We demonstrate the relationship between imaging modes using systematic variation in detector positioning and compare this with pseudo-forescatter electron images, obtained from image analysis of diffraction patterns, to explore and confirm image contrast modes. We demonstrate these contrast mechanisms on a map obtained from a sample of the Gibeon meteorite. KeywordsScanning electron microscopy; electron imaging; electron backscatter diffraction (EBSD); energy dispersive spectroscopy (EDS).

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A theoretical investigation of orientation relationships and transformation strains in steels

Cited by 57 publications

References 21 publications

Hierarchical Eutectoid Nano-lamellar Decomposition in an Al0.3CoFeNi Complex Concentrated Alloy

Hierarchical Eutectoid Nano-lamellar Decomposition in an Al0.3CoFeNi Complex Concentrated Alloy

Crystallographic orientation relationships in the α→γ′ martensitic transformation in an Fe–Mn–Al–Ni system

Space rocks and optimising scanning electron channelling contrast

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