Quantitative analysis of microstructure evolution,stress partitioning and thermodynamics in the dynamic transformation of Fe-14Ni alloy

Lian Li ¹Goro Miyamoto ²Yongjie Zhang ³Miaoquan Li ¹Satoshi Morooka ⁴Katsunari Oikawa ⁵Yo Tomota ⁶Tadashi Furuhara³

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作者信息

1. School of Materials Science and Engineering,Northwestern Polytechnical University,Xi'an 710072,China
2. Institute for Materials Research,Tohoku University,2-1-1 Katahira,Aoba-ku,Sendai 980-8577,Japan;Research Center for Structural Materials,National Institute for Materials Science(NIMS),1-2-1 Sengen,Tsukuba 305-0047,Japan
3. Institute for Materials Research,Tohoku University,2-1-1 Katahira,Aoba-ku,Sendai 980-8577,Japan
4. Materials Sciences Research Center,Japan Atomic Energy Agency,2-4 Shirakata,Tokai,Naka,Ibaraki 319-1195,Japan;J-PARC Center,Japan Atomic Energy Agency,2-4 Shirakata,Tokai,Naka,Ibaraki 319-1195,Japan
5. Department of Materials Science,Graduate School of Engineering,Tohoku University,Sendai 980-8579,Japan
6. National Institute of Advanced Industrial Science and Technology,Central 2,1-1-1 Umezono,Tsukuba,Ibaraki 305-8561,Japan;Graduate School of Science and Engineering,Ibaraki University,4-12-1 Nakanarusawa,Hitach,Ibaraki,316-8511,Japan
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Abstract

Dynamic transformation(DT)of austenite(γ)to ferrite(α)in the hot deformation of various carbon steels was widely investigated.However,the nature of DT remains unclear due to the lack of quantitative analysis of stress partitioning between two phases and the uncertainty of local distribution of substitu-tional elements at the interface in multi-component carbon steels used in the previous studies.Therefore,in the present study,a binary Fe-Ni alloy with α+γ duplex microstructure in equilibrium was prepared and isothermally compressed in α+γ two-phase region to achieve a quantitative analysis of microstruc-ture evolution,stress partitioning,and thermodynamics during DT.γ to α DT during isothermal compres-sion and α to γ reverse transformation on isothermal annealing under unloaded condition after deforma-tion were accompanied by Ni partitioning.The lattice strains during thermomechanical processing were obtained via in-situ neutron diffraction measurement,based on which the stress partitioning behavior between γ and α was discussed by using the generalized Hooke's law.A thermodynamic framework for the isothermal deformation in solids was established based on the basic laws of thermodynamics,and it was shown that the total Helmholtz free energy change in the deformable material during the isothermal process should be smaller than the work done to the deformable material.Under the present thermody-namic framework,the microstructure evolution in the isothermal compression of Fe-14Ni alloy was well explained by considering the changes in chemical free energy,plastic and elastic energies,and the work done to the material.In addition,the stabilization of the soft α phase in Fe-14Ni alloy by deformation was rationalized since the γ to α transformation decreased the total Helmholtz free energy by decreasing the elastic and dislocation energies.

Key words

Iron Nickel/Dynamic transformation/Isothermal deformation/Stress partitioning/Neutron diffraction/Thermodynamics

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基金项目

BL19 in the Materials and Life Science Experimental Facility of J-PARC(2020A0084)

BL19 in the Materials and Life Science Experimental Facility of J-PARC(2020B0036)

JST FOREST Program,Japan(JPMJFR203W)

MEXT through Grantin-Aid for Scientific Research(B)(2019-2021)(19H02473)

Grantin-Aid for Scientific Research on Innovative Areas(2018-2022)(18H05456)

Amada Foundation(2022-2023)()

Amada Foundation(AF-2022017-B2)

China Scholarship Council(201806295030)

出版年

2024

材料科学技术(英文版)

中国金属学会中国材料研究学会中国科学院金属研究所

材料科学技术(英文版)

CSTPCDCSCD

影响因子：0.657

ISSN：1005-0302

参考文献量59

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