Experimental Investigation of Allotropic Transformation of Cobalt: Influence of Temperature Cycle, Mechanical Loading and Starting Microstructure

Iskounen, Nadjib; Dubos, Pierre-Antoine; Fajoui, Jamal; Coret, Michel; Moya, Marie-José; Girault, Baptiste; Barrier, Nicolas; Bruzy, Nicolas; Hug, Éric; Gloaguen, David

doi:10.1007/s11661-021-06142-7

Cited by 8 publications

(3 citation statements)

References 28 publications

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“…The BCC phase volume fraction (denoted f BCC ) was determined, for each measurement point, using the Equation ( 1), as formulated by Bonarski et al [22] and used in previous works [23,24]…”

Section: Methodsmentioning

confidence: 99%

“…The BCC phase volume fraction (denoted f BCC ) was determined, for each measurement point, using the Equation (1), as formulated by Bonarski et al [ 22 ] and used in previous works [ 23,24 ]

f^{\text{BCC}} = \left(\left(\right. 1 + \frac{I_{\text{hkl}}^{\text{FCC}}}{I_{\text{hkl}}^{\text{BCC}}} \frac{R_{\text{hkl}}^{\text{BCC}}}{R_{\text{hkl}}^{\text{HCP}}} \left.\right)\right)^{- 1}

where I hkl is the integrated intensity of the corresponding {hkl} peak and R hkl is the reflectivity of the lattice plane {hkl}, given by the following Equation (2) [ 22 ]

$$R_{\text{hkl}} = \frac{1}{v^{2}} \left(\left|\right.

…”

Section: Methodsmentioning

confidence: 99%

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Dilatometric Study of Continuous Annealing of a Cold‐Rolled Austenitic Stainless Steel

Hayoune,

Maredj,

Fajoui

et al. 2023

steel research int.

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The sequence of structural changes produced in two deformed microstructures of austenitic stainless steel elaborated by a multipass unidirectional cold rolling (CR) and a two‐step one, to a 75% thickness reduction, is followed by dilatometric experiments. The two materials show different dilatometric behaviors. X‐ray diffraction and microhardness measurements are performed to underlie the observed dilatometric behaviors. The material subjected to multipass unidirectional CR shows an unusual dilatometric behavior. The first heating stage leads to the occurrence of the recovery reaction in competition with the ε‐martensite reversion. When the temperature increases between 550 and 780 °C, the reversion of deformation‐induced α‐martensite takes place and leads to a complicated dilatometric anomaly. Further increase in temperature leads to the occurrence of the recrystallization transformation. However, the material subjected to two‐step CR shows a quite usual dilatometric behavior which is explained by the occurrence of several reactions in the following order: 1) T < 300 °C, the recovery reaction, 2) 300 < T < 680 °C, the ferro‐ to paramagnetic transformation of α‐martensite, the reversion of ε‐martensite, and the athermal reversion of α‐martensite, 3) 680 < T < 760 °C, thermal reversion of DIM, and then 4) at T > 760 °C, the recrystallization.

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“…The BCC phase volume fraction (denoted f BCC ) was determined, for each measurement point, using the Equation ( 1), as formulated by Bonarski et al [22] and used in previous works [23,24]…”

Section: Methodsmentioning

confidence: 99%

“…The BCC phase volume fraction (denoted f BCC ) was determined, for each measurement point, using the Equation (1), as formulated by Bonarski et al [ 22 ] and used in previous works [ 23,24 ]

f^{\text{BCC}} = \left(\left(\right. 1 + \frac{I_{\text{hkl}}^{\text{FCC}}}{I_{\text{hkl}}^{\text{BCC}}} \frac{R_{\text{hkl}}^{\text{BCC}}}{R_{\text{hkl}}^{\text{HCP}}} \left.\right)\right)^{- 1}

where I hkl is the integrated intensity of the corresponding {hkl} peak and R hkl is the reflectivity of the lattice plane {hkl}, given by the following Equation (2) [ 22 ]

$$R_{\text{hkl}} = \frac{1}{v^{2}} \left(\left|\right.

…”

Section: Methodsmentioning

confidence: 99%

Dilatometric Study of Continuous Annealing of a Cold‐Rolled Austenitic Stainless Steel

Hayoune,

Maredj,

Fajoui

et al. 2023

steel research int.

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“…However, for very fine grains, it is believed that Co exists primarily in the FCC phase [10]. Additional factors affecting phase stability include strain [12], which, for bulk samples at room temperature, favors the conversion of any residual FCC phase to HCP [14]. The opposite behavior, however, is expected for nanocrystalline Co, which is predicted to undergo deformation via phase transformation from HCP to FCC, as the energy required for a phase transformation is lower than that required to generate twins [15].…”

Section: Cobalt Phasesmentioning

confidence: 99%

Influence of Mn Doping on Local Spin Moments and Stacking Fault Energies in Co(Mn) Alloys

et al. 2023

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We report on the results of first principles calculations investigating the influences of Mn doping on the local moments and stacking fault energies (SFEs) in the Co95.8Mn4.2 and Co91.6Mn8.4 systems as compared to pure face-centered cubic Co. A supercell was developed to maintain periodicity in calculations, provide a simple relaxation mechanism, and allow for easy expansion to accommodate different concentrations of Mn. Calculations to determine the generalized SFE were performed on relaxed and non-relaxed systems in both ferromagnetic and nonmagnetic states. Analysis revealed fluctuations in the magnetic moments that are closely tied to the relaxation state and faulting state of the system. In the case of systems containing Mn, we observed a dependence of the SFE on the location of the Mn atom(s) within the supercell relative to the stacking fault interface and a strong induced magnetic moment for these atoms.

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Mechanical response, deformation and damage mechanisms in dual-phase cobalt upon plate impact

Chen,

Cai,

Chen

et al. 2024

J Mater Sci

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Experimental Investigation of Allotropic Transformation of Cobalt: Influence of Temperature Cycle, Mechanical Loading and Starting Microstructure

Cited by 8 publications

References 28 publications

Dilatometric Study of Continuous Annealing of a Cold‐Rolled Austenitic Stainless Steel

Dilatometric Study of Continuous Annealing of a Cold‐Rolled Austenitic Stainless Steel

Influence of Mn Doping on Local Spin Moments and Stacking Fault Energies in Co(Mn) Alloys

Mechanical response, deformation and damage mechanisms in dual-phase cobalt upon plate impact

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