Alloying effects on the elastic parameters of ferromagnetic and paramagnetic Fe from first-principles theory

Zhang, Hualei; Al-Zoubi, Noura; Johansson, Börje; Vitos, Levente

doi:10.1063/1.3644907

Cited by 25 publications

(9 citation statements)

References 39 publications

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“…This is in line with the observation that Cr decreases the tetragonal elastic constant of paramagnetic fcc Fe 0.9 Cr 0.1 . 40 Investigating Fig. 2, we observe that substituting 5% Mn for Fe in the Fe 0.9 Cr 0.1 alloy increases the energy differences between fcc and bcc (relative to that of Fe 0.9 Cr 0.1 ) by Nickel and cobalt are calculated to have pronounced effects on the Bain path of paramagnetic Fe-Cr alloys.…”

Section: A Total Energy Mapsmentioning

confidence: 76%

“…6, introducing 5% Co into fcc Fe 0.90 Cr 0.10 increases DE fcc (1.35) by 0.01 mRy, which correlates well with the large positive effect of Co on C 0 fcc of paramagnetic Fe 1Àx Co x . 40 Manganese has a rather small effect on the bct-fcc structural energy difference, in line with its negligible impact on C 0 fcc . 40 For large distortions (0.055 !…”

Section: Tetragonal Distortions Around the Cubic Phasesmentioning

confidence: 82%

“…40 Manganese has a rather small effect on the bct-fcc structural energy difference, in line with its negligible impact on C 0 fcc . 40 For large distortions (0.055 ! d !…”

Section: Tetragonal Distortions Around the Cubic Phasesmentioning

confidence: 82%

“…It is interesting to contrast the above trends for the energy barrier with those calculated for the elastic constants of paramagnetic fcc Fe alloys. 40 In particular, Ni(Co) was predicted to decrease(increase) the tetragonal elastic constant of fcc Fe. Thus, we may conclude that the trends in the elastic constants are not sufficient to predict the changes in the energy barrier upon alloying.…”

Section: A Total Energy Mapsmentioning

confidence: 99%

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The Bain path of paramagnetic Fe-Cr based alloys

Al-Zoubi¹,

Johansson²,

Nilson³

et al. 2011

Journal of Applied Physics

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Structural stability and magnetic properties in X 2 Al X ′ (X= Fe , Co, Ni; X ′ = Ti , Cr) Heusler alloys from quantum mechanical calculations Employing the first-principles exact muffin-tin orbital method in combination with the coherent potential approximation, we calculated the total energy and local magnetic moments of paramagnetic Fe-Cr-M (M ¼ Cr, Mn, Fe, Co, Ni) alloys along the tetragonal distortion (Bain) path connecting the body centered cubic (bcc) and the face centered cubic (fcc) structures. The paramagnetic phase is modeled by the disordered local magnetic moment scheme. For all alloys, the local magnetic moments on Fe atoms decrease from the maximum value corresponding to the bcc phase toward the minimum value realized for the fcc phase. Cobalt atoms have non-vanishing local magnetic moments only for tetragonal lattices with c/a < 1.30, whereas the local magnetic moments of Mn show weak crystal structure dependence. We find that Cr stabilizes the bcc lattice and increases the energy barrier as going from the bcc toward the fcc phase. Both Co and Ni favor the fcc lattice and decrease the energy barrier relative to the bcc phase. On the other hand, the tetragonal distortion around the fcc phase is facilitated by Cr and to a somewhat lesser extent also by Ni, but strongly impeded by Co. Manganese has negligible effect on the structural energy difference as well as on the energy barrier along the Bain path. Our findings on the alloying induced softening or hardening of Fe-Cr based alloys against tetragonal distortions are important for understanding the interstitial driven martensitic transformations in alloy steels.

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Section: A Total Energy Mapsmentioning

confidence: 76%

Section: Tetragonal Distortions Around the Cubic Phasesmentioning

confidence: 82%

“…40 Manganese has a rather small effect on the bct-fcc structural energy difference, in line with its negligible impact on C 0 fcc . 40 For large distortions (0.055 ! d !…”

Section: Tetragonal Distortions Around the Cubic Phasesmentioning

confidence: 82%

Section: A Total Energy Mapsmentioning

confidence: 99%

See 2 more Smart Citations

The Bain path of paramagnetic Fe-Cr based alloys

Al-Zoubi¹,

Johansson²,

Nilson³

et al. 2011

Journal of Applied Physics

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“…Within the DLM picture, a paramagnetic Fe-Cr-Ni-M quaternary alloy is described as an eight-component (Fe ↑ Fe ↓ ) 0.6−x (Cr ↑ Cr ↓ ) 0.2 (Ni ↑ Ni ↓ ) 0.2 (M ↑ M ↓ ) x alloy with equal amounts of spin up (↑) and spin down (↓) components. Using the DLM scheme, the impact of the loss of the magnetic moment above the Curie temperature on the total energy is properly taken into account, although our calculations were formally still performed at 0 K.The equations of state and elastic parameters of the present Fe-based alloys and transition metal alloys were calculated using the EMTO method which was used in several former works [9,11,[24][25][26][27][28][29][30][31].…”

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confidence: 99%

Elastic Parameters of Paramagnetic Fe–20Cr–20Ni-Based Alloys: A First-Principles Study

Al-Zoubi

2019

Metals

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The single-crystal and polycrystalline elastic parameters of paramagnetic Fe 0.6−x Cr 0.2 Ni 0.2 M x (M = Al, Co, Cu, Mo, Nb, Ti, V, and W; 0 ≤ x ≤ 0.08) alloys in the face-centered cubic (fcc) phase were derived by first-principles electronic structure calculations using the exact muffin-tin orbitals method. The disordered local magnetic moment approach was used to model the paramagnetic phase. The theoretical elastic parameters of the present Fe-Cr-Ni-based random alloys agree with the available experimental data. In general, we found that all alloying elements have a significant effect on the elastic properties of Fe-Cr-Ni alloy, and the most significant effect was found for Co. A correlation between the tetragonal shear elastic constant C and the structural energy difference ∆E between fcc and bcc lattices was demonstrated. For all alloys, small changes in the Poisson's ratio were obtained. We investigated the brittle/ductile transitions formulated by the Pugh ratio. We demonstrate that Al, Cu, Mo, Nb, Ti, V, and W dopants enhance the ductility of the Fe-Cr-Ni system, while Co reduces it. The present theoretical data can be used as a starting point for modeling the mechanical properties of austenitic stainless steels at low temperatures. of the alloying effects on the elastic parameters of paramagnetic fcc Fe-20Cr-20Ni-xM. Specifically, we investigated the changes in the single-crystal and polycrystalline elastic constants caused by adding small concentrations of M (M = Al, Co, Cu, Mo, Nb, V, and W; 0 ≤ x ≤ 8, where x is in atom %) that are soluble in the Fe-Cr-Ni system. We chose these alloying elements since they represent simple metal (Al), as well as nonmagnetic (Cu, Mo, Nb, V, and W) and magnetic (Co) transition metals. We excluded Cr and Ni from this study, since the effects of these alloying elements on the elastic properties of a paramagnetic fcc Fe-Cr-Ni system were discussed previously by Vitos et al. [11].In the present work, all quaternary alloys were treated as substitutional disordered paramagnetic solid solutions with an ideal fcc structure. The paramagnetic phase was modeled using a disordered local moment scheme, which describes the systems well above the magnetic transition temperatures.The rest of the paper includes two sections and conclusions. In Section 2, we describe the ab initio method, the elastic parameters, and the details of the numerical calculations. We present the results and the discussion in Section 3. Methodology Total Energy CalculationsThe calculations in this work are based on density functional theory [12,13] and the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation [14] for the exchange correlation functional. The exact muffin-tin orbitals (EMTO) method [10,[15][16][17][18][19] in combination with the scalar-relativistic scheme and soft-core approximation was used to solve the Kohn-Sham equations. The chemical and magnetic substitutional disorder was treated using coherent potential approximation (CPA) [20,21]. The total energy was computed using full char...

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