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Träfflista för sökning "WFRF:(Dong Zhihua) srt2:(2017)"

Sökning: WFRF:(Dong Zhihua) > (2017)

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1.
  • Dong, Zhihua, et al. (författare)
  • Elastic properties of paramagnetic austenitic steel at finite temperature : Longitudinal spin fluctuations in multicomponent alloys
  • 2017
  • Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 96:17
  • Tidskriftsartikel (refereegranskat)abstract
    • We propose a first-principles framework for longitudinal spin fluctuations (LSFs) in disordered paramagnetic (PM) multicomponent alloy systems and apply it to investigate the influence of LSFs on the temperature dependence of two elastic constants of PM austenitic stainless steel Fe15Cr15Ni. The magnetic model considers individual fluctuating moments in a static PM medium with first-principles-derived LSF energetics in conjunction with describing chemical disorder and randomness of the transverse magnetic component in the single-site alloy formalism and disordered local moment (DLM) picture. A temperature-sensitive mean magnetic moment is adopted to accurately represent the LSF state in the elastic-constant calculations. We make evident that magnetic interactions between an LSF impurity and the PM medium are weak in the present steel alloy. This allows gaining accurate LSF energetics and mean magnetic moments already through a perturbation from the static DLM moments instead of a tedious self-consistent procedure. We find that LSFs systematically lower the cubic shear elastic constants c' and c(44) by similar to 6 GPa in the temperature interval 300-1600 K, whereas the predominant mechanism for the softening of both elastic constants with temperature is the magneto-volume coupling due to thermal lattice expansion. We find that non-negligible local magnetic moments of Cr and Ni are thermally induced by LSFs, but they exert only a small influence on the elastic properties. The proposed framework exhibits high flexibility in accurately accounting for finite-temperature magnetism and its impact on the mechanical properties of PM multicomponent alloys.
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2.
  • Dong, Zhihua, et al. (författare)
  • Longitudinal spin fluctuation contribution to thermal lattice expansion of paramagnetic Fe
  • 2017
  • Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 95:5
  • Tidskriftsartikel (refereegranskat)abstract
    • Using an efficient first-principles computational scheme for paramagnetic body-centered cubic (bcc) and face-centered cubic (fcc) Fe, we investigate the impact of thermal longitudinal spin fluctuations (LSFs) on the thermal lattice expansion. The equilibrium physical parameters are derived from the self-consistent Helmholtz free energy, in which the LSFs are considered within the adiabatic approximation and the anharmonic lattice vibration effect is included using the Debye-Gruneisen model taking into account the interplay between thermal, magnetic, and elastic degrees of freedom. Thermal LSFs are energetically more favorable in the fcc phase than in the bcc one giving a sizable contribution to the linear thermal expansion of gamma-Fe. The present scheme leads to accurate temperature-dependent equilibriumWigner-Seitz radius, bulk modulus, and Debye temperature within the stability fields of the two phases and demonstrates the importance of thermal spin fluctuations in paramagnetic Fe.
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  • Resultat 1-2 av 2
Typ av publikation
tidskriftsartikel (2)
Typ av innehåll
refereegranskat (2)
Författare/redaktör
Long, Mujun (2)
Chen, Dengfu (2)
Dong, Zhihua (2)
Vitos, Levente (2)
Schönecker, Stephan (2)
Li, Wei (2)
Lärosäte
Kungliga Tekniska Högskolan (2)
Uppsala universitet (2)
Språk
Engelska (2)
Forskningsämne (UKÄ/SCB)
Naturvetenskap (2)
År
2017 (2)Ta bort avgränsningen

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