Effects of grain size on coercivity of combined-reaction-processed FePd intermetallics

Deshpande, A.R.; Xu, Huiping; Wiezorek, J.M.K.

doi:10.1016/j.actamat.2004.02.036

Cited by 31 publications

(36 citation statements)

References 11 publications

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“…The existence of the bct phase can be considered as a reason for all the structural peculiarities of the L1 0 alloys that were reported in earlier papers [7][8][9][10][11][12][13][14]20,[22][23][24][52][53][54][55]. Among them one can pick out: (1) the difference in the c/a ratio determined from the fundamental and superlattice reflections [7]; (2) the existence of inequality c/a -1 in the case of unsplit reflections (i.e.…”

Section: Resultsmentioning

confidence: 99%

“…In the majority of theoretical and experimental works (e.g. [4][5][6][7][8][9][10][11][12][13][14][15]) the tetragonal distortion of the crystal lattice, which arises in the alloys upon the phase transformation A1 ! L1 0 , is considered to result exclusively from layer-by-layer distribution of atoms of different kinds in the directions h100i (Fig.…”

Section: Introductionmentioning

confidence: 99%

“…It is experimentally shown that variation of temperature and duration of the ordering annealing and application of magnetic field or stresses in the course of this annealing, as well as of preliminary plastic deformation, are factors that exert a significant effect on the integral degree of long ordering, morphology and sizes of the meso-and microstructure elements of L1 0 alloys [7][8][9][10][11][12][13][14]. In the majority of theoretical and experimental works (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Discovery of metastable tetragonal disordered phase upon phase transitions in the equiatomic nanostructured FePd alloy

et al. 2013

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Specific features of the phase transformation A1 ! L1 0 (space groups Fm3m and P4/mmm, respectively) in single crystals of the equiatomic alloy FePd subjected to annealings both in the absence and in the presence of external uniaxial load, as well as in polycrystalline samples that had undergone severe plastic deformation via high-pressure torsion and subsequent annealing, have been studied. An investigation of the single crystals in a nanostructured state formed at different stages of ordering annealing was performed using optical polarization, thermomagnetic and transmission electron microscopy (TEM) methods. The nanostructured state of the polycrystalline samples FePd after deformation of both disordered and ordered FePd alloys and subsequent annealing was examined with the help of TEM and X-ray techniques. The results obtained were analyzed based on the known concepts of the symmetry theory of phase transitions. It was concluded that the atomic ordering in the FePd alloys is preceded by the formation of a ferroelastic disordered bodycentered tetragonal phase with the structural type A6 and the space group I4/mmm. Experimental data that evidence the existence of a tetragonal disordered phase both in the single crystals and in the polycrystalline samples of FePd after severe plastic deformation and subsequent annealing are reported. Thus, the A1 M A6 M L1 0 phase transformation represents a combination of different types of phase transitions such as cooperative displacement A1 M A6 and ordering A6 M L1 0 of atoms.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Discovery of metastable tetragonal disordered phase upon phase transitions in the equiatomic nanostructured FePd alloy

et al. 2013

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“…It is known that the coercivity depends on the grain size, d,: the 1=d-dependence of coercivity above the critical size 11) and the extraordinary d 6 -dependence of coercivity below the critical size.…”

Section: Resultsmentioning

confidence: 99%

Ferromagnetic Properties of Co-Cu Alloy with Nanoscale Lamellar Structure

et al. 2009

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Co-Cu alloys containing a nanoscale lamellar structure with a spacing of 3 nm were produced by electrodeposition, and the effects of annealing on the ferromagnetic properties of the electrodeposited Co-Cu alloys were investigated at room temperature. Both the saturation magnetization and the coercivity were decreased by annealing. This is related to a change in the lamellar structure upon annealing. It is suggested that in the d 6 -dependence range of coercivity, the lamellar boundaries play a different role from the grain boundaries.

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“…[11] They are attractive for both thin film device applications (high density magnetic recording media) [12] and permanent magnets. [13] In spite of their relatively high cost, these materials are attractive for some specific applications like medical implants or extreme conditions where high strength and excellent corrosion resistance are required. It has been shown that their coercivity strongly depends on grain size.…”

Section: Introductionmentioning

confidence: 99%

Optimization of the Magnetic Properties of FePd Alloys by Severe Plastic Deformation

et al. 2010

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A FePd alloy was nanostructured by severe plastic deformation following two different routes: ordered and disordered states were processed by high pressure torsion (HPT). A grain size in a range of 50 to 150 nm is obtained in both cases. Severe plastic deformation induces some significant disordering of the long range ordered L1 0 phase. However, Transmission Electron Microscopy (TEM) data clearly show that few ordered nanocrystals remain in the deformed state. The deformed materials were annealed to achieve nanostructured long range ordered alloys. The transformation proceeds via a first order transition characterized by the nucleation of numerous ordered domains along grain boundaries. The influence of the annealing conditions (temperature and time) on the coercivity was studied for both routes. It is demonstrated that starting with the disorder state prior to HPT and annealing at low temperature (400°C) leads to the highest coercivity (about 1.8 kOe).

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Effects of grain size on coercivity of combined-reaction-processed FePd intermetallics

Cited by 31 publications

References 11 publications

Discovery of metastable tetragonal disordered phase upon phase transitions in the equiatomic nanostructured FePd alloy

Discovery of metastable tetragonal disordered phase upon phase transitions in the equiatomic nanostructured FePd alloy

Ferromagnetic Properties of Co-Cu Alloy with Nanoscale Lamellar Structure

Optimization of the Magnetic Properties of FePd Alloys by Severe Plastic Deformation

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