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Tian, Ye
Publications (9 of 9) Show all publications
Levämäki, H., Tian, Y., Vitos, L. & Ropo, M. (2019). An automated algorithm for reliable equation of state fitting of magnetic systems. Computational materials science, 156, 121-128
Open this publication in new window or tab >>An automated algorithm for reliable equation of state fitting of magnetic systems
2019 (English)In: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 156, p. 121-128Article in journal (Refereed) Published
Abstract [en]

In computational physics and materials science ground-state properties are often extracted from an equation of state fit to energy-volume data. Magnetic systems often have multiple magnetic phases present in the energy-volume data, which poses a challenge for the fitting approach because the results are sensitive to the selection of included fitting points. This is because practically all popular equation of state fitting functions, such as Murnaghan and Birch-Murnaghan, assume just one phase and therefore cannot correctly fit magnetic energy-volume data that contains multiple phases. When fitting magnetic energy-volume data it is therefore important to select the range of fitting points in such a way that only points from the one relevant phase are included. We present a simple algorithm that makes the point selection automatically. Selecting fitting points automatically removes human bias and should also be useful for large-scale projects where selecting all fitting points by hand is not feasible.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
EOS, Equation of state fitting, Ground state, Magnetism, Automated algorithms, Computational physics, Equation of state, Fitting functions, Ground state properties, Large-scale projects, Magnetic energies, SIMPLE algorithm, Equations of state
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-236337 (URN)10.1016/j.commatsci.2018.09.026 (DOI)000449375500015 ()2-s2.0-85053772857 (Scopus ID)
Note

QC 20181109

Available from: 2018-11-09 Created: 2018-11-09 Last updated: 2020-01-30Bibliographically approved
Wang, W., Hou, Z., Lizarrága, R., Tian, Y., Babu, P., Holmström, E., . . . Larsson, H. (2019). An experimental and theoretical study of duplex fcc+hcp cobalt based entropic alloys. Acta Materialia, 176, 11-18
Open this publication in new window or tab >>An experimental and theoretical study of duplex fcc+hcp cobalt based entropic alloys
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2019 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 176, p. 11-18Article in journal (Refereed) Published
Abstract [en]

Martensitically formed duplex fcc + hcp Co-based entropic alloys have been investigated both experimentally and theoretically. Theoretical predictions are in good agreement with experimental observations. A fair correlation is found between calculated driving forces for a partitionless fcc→hcp transformation and experimentally obtained phase fractions.

Place, publisher, year, edition, pages
Elsevier, 2019
National Category
Metallurgy and Metallic Materials
Research subject
Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-258027 (URN)10.1016/j.actamat.2019.06.041 (DOI)000482247800002 ()2-s2.0-85068362090 (Scopus ID)
Note

QC 20190917

Available from: 2019-09-09 Created: 2019-09-09 Last updated: 2020-02-19Bibliographically approved
Tian, Y., Forsberg, A. & Hedström, P. (2018). Comparing the deformation-induced martensitic transformation with the athermal martensitic transformation in Fe-Cr-Ni alloys. Journal of Alloys and Compounds, 766, 131-139
Open this publication in new window or tab >>Comparing the deformation-induced martensitic transformation with the athermal martensitic transformation in Fe-Cr-Ni alloys
2018 (English)In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 766, p. 131-139Article in journal (Refereed) Published
Abstract [en]

The microstructure of martensite formed athermally or via deformation in Fe-Cr-Ni alloys with different austenite (gamma) stability has been investigated using microscopy. Two different types of microstructures, viz. blocky and banded structure, are observed after athermal and deformation-induced martensitic transformation (AMT and DIMT, respectively). The blocky structure form during AMT or DIMT if the stability of gamma is low. In both cases, there is a significant chemical driving force for the transformation from gamma to alpha'-martensite (alpha'), and if it is not hindered by e.g. planar defects it can grow uninhibited into a blocky morphology without the necessity to nucleate new crystallographic variants to accommodate the transformation strains. On the other hand, the banded structure is due to the formation of epsilon-martensite (epsilon) during AMT, or the wider concept shear bands in the case of DIMT. The shear bands, and in particular epsilon, lower the nucleation barrier for alpha' that forms within individual shear bands if the stability of gamma is low. Neighbouring alpha' units predominantly have a twin-related orientation relationship to accommodate the transformation strains. With increasing y stability during DIMT, variant selection becomes pronounced with preferred formation of variants favorable oriented with respect to the applied stress/strain field. The formation of alpha' at individual shear bands is also rare, since nos is present and instead alpha' forms at the intersection of shear bands for more stable gamma. In conclusion, AMT and DIMT for low gamma stability lead to similar microstructures, whereas the DIMT microstructure for high y stability is distinct. 

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2018
Keywords
Metastable austenite, Deformation-induced martensitic transformation, Deformation microstructure, Variant pairing tendency, Variant selection
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-235554 (URN)10.1016/j.jallcom.2018.06.326 (DOI)000444617200014 ()2-s2.0-85049301116 (Scopus ID)
Note

QC 20181002

Available from: 2018-10-02 Created: 2018-10-02 Last updated: 2018-10-02Bibliographically approved
Tian, Y. (2018). Martensitic Transformation in Stainless Steels. (Doctoral dissertation). KTH Royal Institute of Technology
Open this publication in new window or tab >>Martensitic Transformation in Stainless Steels
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2018. p. 62
Series
TRITA-ITM-AVL ; 2018:28
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-228054 (URN)978-91-7729-786-4 (ISBN)
Public defence
2018-06-14, Kollegiesalen, Brinellvägen 8, Stockholm, 10:00 (English)
Opponent
Supervisors
Available from: 2018-05-17 Created: 2018-05-16 Last updated: 2019-08-20Bibliographically approved
Tian, Y., Lin, S., Ko, J. Y., Lienert, U., Forsberg, A. & Hedström, P. (2018). Micromechanics and microstructure evolution during in situ uniaxial tensile loading of TRIP-assisted duplex stainless steels. Materials Science & Engineering: A, 734, 281-290
Open this publication in new window or tab >>Micromechanics and microstructure evolution during in situ uniaxial tensile loading of TRIP-assisted duplex stainless steels
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2018 (English)In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 734, p. 281-290Article in journal (Refereed) Published
Abstract [en]

Transformation-induced plasticity (TRIP) assisted duplex stainless steels, with three different stabilities of the austenite phase, were investigated by synchrotron x-ray diffraction characterization during in situ uniaxial tensile loading. The micromechanics and the deformation-induced martensitic transformation (DIMT) in the bulk of the steels were investigated in situ. Furthermore, scanning electron microscopy supplemented the in situ analysis by providing information about the microstructure of annealed and deformed specimens. The dependence of deformation structure on austenite stability is similar to that of single-phase austenitic steels with shear bands and bcc-martensite (α′) generally observed, and blocky α′ is only frequent when the austenite stability is low. These microstructural features, i.e. defect structure and deformation-induced martensite, are correlated with the micro- and macro-mechanics of the steels with elastoplastic load transfer from the weaker phases to the stronger α′, in particular this occurs close to the point of maximum rate of α′ formation. A clear strain-hardening effect from α′ is seen in the most unstable austenite leading to a pronounced TRIP effect. 

Place, publisher, year, edition, pages
Elsevier Ltd, 2018
Keywords
Duplex stainless steel, in situ tensile loading, Load partitioning, Micromechanics, Synchrotron x-ray diffraction, TRIP-assisted steel, Austenite, Austenitic transformations, Crystal structure, Deformation, High strength steel, Martensite, Martensitic transformations, Microstructural evolution, Plasticity, Scanning electron microscopy, Strain hardening, Synchrotron radiation, Tensile stress, X ray diffraction, Deformation-induced martensite, In-situ tensile, Micro-structure evolutions, Microstructural features, Synchrotron x ray diffraction, Transformation induced plasticity, TRIP-assisted steels, Loading
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-236692 (URN)10.1016/j.msea.2018.07.040 (DOI)000445993900032 ()2-s2.0-85050988500 (Scopus ID)
Funder
VINNOVA
Note

Export Date: 22 October 2018; Article; Correspondence Address: Tian, Y.; Department of Materials Science and Engineering, KTH Royal Institute of TechnologySweden; email: yti@kth.se; Funding details: CSC, China Scholarship Council; Funding details: 2i; Funding details: Axelrod Family Foundation; Funding details: VINNOVA; Funding details: Jernkontoret; Funding details: DMR-1332208, BSF, United States-Israel Binational Science Foundation; Funding text: This work was performed within the VINN Excellence Centre Hero-m 2i, financed by VINNOVA , the Swedish Government Agency of Innovation Systems , Swedish Industry and KTH . This work is based upon research conducted at the Cornell High Energy Synchrotron Source (CHESS) which is supported by the United States National Science Foundation under award DMR-1332208 . The authors are grateful to Darren Dale, Margaret Koker, Prasath Babu R, Yan Ma, Fei Huyan, Sven Gutschmidt and Basil Blank for technical assistance, and Jan Y. Jonsson from Outokumpu for providing the materials. Y. Tian would like to express his gratitude to the support from CSC (China Scholarship Council) and Axel Hultgrens foundation. P. Hedström acknowledges the support from Jernkontoret (Swedish Steel Producers’ association). QC 20181112

Available from: 2018-11-12 Created: 2018-11-12 Last updated: 2018-11-12Bibliographically approved
Tian, Y., Lienert, U., Borgenstam, A., Fischer, T. & Hedström, P. (2017). Martensite formation during incremental cooling of Fe-Cr-Ni alloys: An in-situ bulk X-ray study of the grain-averaged and single-grain behavior. Scripta Materialia, 136, 124-127
Open this publication in new window or tab >>Martensite formation during incremental cooling of Fe-Cr-Ni alloys: An in-situ bulk X-ray study of the grain-averaged and single-grain behavior
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2017 (English)In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 136, p. 124-127Article in journal (Refereed) Published
Abstract [en]

The formation of martensite (epsilon and alpha') in metastable austenitic Fe-18Cr-(10-11.5)Ni alloys was investigated in situ during cooling. High-energy X-rays were used to study the bulk of the alloys. Both grain-averaged and single grain data was acquired. s played an important role in the formation of a' with an indistinguishable difference in the martensite start temperature. The single-grain data indicated that stacking faults appear as precursors to a An analogy can be made with deformation-induced martensitic transformation, where the generation of nucleation sites would significantly lower the driving force required to overcome the energy barrier in low stacking fault energy Fe-Cr-Ni alloys.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Martensitic phase transformation, Synchrotron radiation, Austenitic stainless steel, In-situ investigation, Three-dimensional X-ray diffraction (3DXRD)
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-210454 (URN)10.1016/j.scriptamat.2017.04.020 (DOI)000402943600028 ()2-s2.0-85018433587 (Scopus ID)
Funder
VINNOVA
Note

QC 20170706

Available from: 2017-07-06 Created: 2017-07-06 Last updated: 2018-05-16Bibliographically approved
Tian, Y., Borgenstam, A. & Hedström, P. Comparing the deformation-induced martensitic transformation with the athermal martensitic transformation in Fe-Cr-Ni alloys.
Open this publication in new window or tab >>Comparing the deformation-induced martensitic transformation with the athermal martensitic transformation in Fe-Cr-Ni alloys
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The microstructure of martensite formed athermally or via deformation in Fe-Cr-Ni alloys with different austenite (γ) stability has been investigated using microscopy. Two different types of microstructures, viz. blocky and banded structure, are observed after athermal and deformation-induced martensitic transformation (AMT and DIMT, respectively). The blocky structure form during AMT or DIMT if the stability of γ is low. In both these cases, there is a significant chemical driving force for the transformation from γ to α’-martensite (α’), and if it is not hindered by e.g. planar defects it can grow uninhibited into a blocky morphology without the necessity to nucleate new crystallographic variants to accommodate the transformation strains. On the other hand, the banded structure is due to the formation of ε-martensite (ε) during AMT, or the wider concept shear bands in the case of DIMT. The shear bands, and in particular ε, lower the nucleation barrier for α’ that forms within individual shear bands if the stability of γ is low. Neighbouring α’ units predominantly have a twin-related orientation relationship to accommodate the transformation strains. With increasing γ stability during DIMT, variant selection becomes pronounced with preferred formation of variants favourable oriented with respect to the applied stress/strain field. The formation of α’ at individual shear bands is also rare, since no ε is present and instead α’ forms at the intersection of shear bands for more stable γ. In conclusion, AMT and DIMT for low γ stability lead to similar microstructures, whereas the DIMT microstructure for high γ stability is distinct.

National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-228048 (URN)
Note

QC 20180522

Available from: 2018-05-16 Created: 2018-05-16 Last updated: 2019-12-20Bibliographically approved
Tian, Y., Das, Y., Borgenstam, A. & Hedström, P.Mechanical stability of austenite grains towards martensitic transformation in a TRIP-assisted duplex stainless steel.
Open this publication in new window or tab >>Mechanical stability of austenite grains towards martensitic transformation in a TRIP-assisted duplex stainless steel
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The mechanical behavior of austenite was investigated in a TRIP duplex stainless steel (TDSS). Uniaxial tensile testing was performed and the microstructure was characterized using electron backscatter diffraction. A strong <111> texture develops along the loading direction (LD) due to preferential martensitic transformation and grain rotation. Austenite oriented with <112> and <100> parallel to the LD transform preferentially, since multiple slip planes activate for these orientations. These observations agree with observations in single-phase austenitic alloys with low stacking fault energy. In conclusion, it is indicated that the stability of austenite grains towards martensitic transformation is mainly dictated by crystallographic orientation.

National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-228050 (URN)
Note

QC 20180522

Available from: 2018-05-16 Created: 2018-05-16 Last updated: 2019-12-20Bibliographically approved
Tian, Y., Lin, S., Peter Ko, J. Y., Lienert, U., Borgenstam, A. & Hedström, P.Micromechanics and microstructure evolution during in situ uniaxial tensile loading of TRIP-assisted duplex stainless steels.
Open this publication in new window or tab >>Micromechanics and microstructure evolution during in situ uniaxial tensile loading of TRIP-assisted duplex stainless steels
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Two transformation-induced plasticity (TRIP) assisted duplex stainless steels, with three different stabilities of the austenite phase, were investigated by synchrotron X-ray diffraction characterization during in situ uniaxial tensile loading. The micromechanics and the deformation-induced martensitic transformation (DIMT) in the bulk of the steels were investigated in situ. Furthermore, scanning electron microscopy supplemented the in situ analysis by providing information about the microstructure of annealed and deformed specimens. The dependence of deformation structure on austenite stability is similar to that of single-phase austenitic steels where shear bands and bcc-martensite (α’) are generally observed, and blocky α’ is only frequent when the austenite stability is low. These microstructural features, i.e. defect structure and deformation-induced martensite, are correlated with the micro- and macro-mechanics of the steels with elastoplastic load transfer from the weaker phases to the stronger α’, in particular this occurs close to the point of maximum rate of α’ formation. A clear strain-hardening effect from α’ is seen in the most unstable austenite leading to a pronounced TRIP effect.

National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-228049 (URN)
Note

QC 20180522

Available from: 2018-05-16 Created: 2018-05-16 Last updated: 2019-12-20Bibliographically approved
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