Magnetic properties and structure of Fe–Pt–M–B (M=Zr, Nb and Ti) alloys produced by quenching technique

Makino, Akihiro; Bitoh, Teruo; Inoue, Akihisa; Hirotu, Yoshihiko

doi:10.1016/j.jallcom.2006.08.092

Cited by 11 publications

(3 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There have been reports on the preparation and characterization of quaternary alloys Fe–Pt–M–B, where M = Zr, Nb, and Ti. Makino et al [ 8 , 9 , 10 ] studied the (Fe 0.55 Pt 0.45 )–M–B alloys formed by rapid quenching and the quaternary Fe-Pt-Zr-B alloy with equiatomic Fe/Pt ratio. For the (Fe 0.50 Pt 0.50 ) 78 Zr 4 B 18 alloy they obtained the best magnetic properties, i.e., a coercivity value of Hc = 688 kA/m.…”

Section: Introductionmentioning

confidence: 99%

Temperature-Dependent Phase Evolution in FePt-Based Nanocomposite Multiple-Phased Magnetic Alloys

Crisan

Randrianantoandro

2022

Nanomaterials

View full text Add to dashboard Cite

A quaternary Fe–Pt–Nb–B alloy has been fabricated by the melt spinning method with the purpose of the formation of crystallographically coherent multiple magnetic phases, emerging from the same metastable precursor, as well as to investigate the phase interactions and the influence of their coupling on magnetic performances. For this purpose, extended structural and magnetic investigations were undertaken by making use of X-ray diffraction, transmission electron microscopy, and 57Fe Mössbauer spectroscopy, as well as magnetic measurements using SQUID magnetometry. It was documented that intermediate metastable phases formed during primary crystallization, in intermediate stages of annealing, and a growth-dominated mode was encountered for the secondary crystallization stage upon annealing at 700 °C and 800 °C where fcc Fe3Pt and fct Fe2B polycrystalline were formed. The Mössbauer investigations have documented rigorously the hyperfine parameters of each of the observed phases. The fcc A1 FePt phase was shown to exhibit a peculiar ferromagnetic transition, and this transition has been proven to occur gradually between 300 K and 77 K. The magnetic measurements allowed us to identify the annealing at 700 °C as optimal for obtaining good magnetic features. Coercive field dependence shows similarities to the random anisotropy model for samples annealed at 500 °C to 700 °C which are nanocrystalline. These results show good perspectives for use in applications where different magnetic states are required at different operating temperatures.

show abstract

Section: Introductionmentioning

confidence: 99%

Temperature-Dependent Phase Evolution in FePt-Based Nanocomposite Multiple-Phased Magnetic Alloys

Crisan

Randrianantoandro

2022

Nanomaterials

View full text Add to dashboard Cite

show abstract

“…However, a reduction of the ordering temperature required for L1 0 phase formation can be obtained via suitable modulation of the stoichiometry, for example by adding other elements to the composition. In the case of the FePt system, noble metals such as Au, Ag or Nb have been considered as suitable additions, having the role of promoting early ordering by segregation to the (Fe,Co)Pt grain boundaries [7][8][9][10][11][12][13][14] while a glass-forming element such as boron has been added to FePt to allow synthesis by out-of-equilibrium techniques such as rapid solidification from the melt [15][16][17][18][19][20][21].Chang et al [22] have studied the effect of Co substitution on the magnetic properties of melt-spun (Fe,Co)-Pt-B nanocomposite ribbons and found that Co substitution enhances the coercivity and energy product due to the formation of ordered L1 0 -(Fe,Co)Pt phase with higher anisotropy field. Makino et al [23] obtained the crystalline ordered L1 0 -FePt phase, with high coercivity, directly formed by rapid quenching of the melt in (Fe,Co)-Pt-Zr-B system, in the compositional range of 2-5 at.…”

mentioning

confidence: 99%

“…It has been shown that Nb addition [9] to FePt enables the enhancement of magnetic properties. Boron added to the stoichiometry [10,11] also ensures improvements of the microstructure. In the case of thin films of composition FePtAg [13] Ag has been beneficial for lowering the temperature of the phase transformation.…”

mentioning

confidence: 99%

Annealing-Induced High Ordering and Coercivity in Novel L10 CoPt-Based Nanocomposite Magnets

Crisan

Vasiliu

Mercioniu

et al. 2018

Metals

View full text Add to dashboard Cite

A novel class of quaternary intermetallic alloys based on CoPt is investigated in view of their interesting magnetic properties induced by the presence of hard magnetic L1 0 phase. A Co 48 Pt 28 Ag 6 B 18 alloy has been prepared by rapid solidification from the melt and subjected to various isothermal annealing procedures. The structure and magnetism of both as-cast and annealed samples as well as the phase evolution with temperature are investigated by means of thermal analysis, X-ray, and selected area electron diffraction, scanning and high-resolution electron microscopy, and magnetic measurements. The X-ray diffraction (XRD) analysis shows that both the as-cast alloy and the sample annealed at 400 • C (673 K) have a nanocrystalline structure where fcc CoPt phase predominates. Annealing at 473 • C promotes the formation of L1 0 phase triggered by the disorder-order phase transformation as documented in the differential scanning calorimetry results. The sample annealed at 670 • C (943 K) shows full formation of L1 0 CoPt as revealed by XRD. Magnetic measurements showed coercivity values ten times increased compared to the as-cast state. This confirms the full formation of L1 0 CoPt in the annealed samples. Moreover, detailed atomic resolution HREM images and SAED patterns show the occurrence of the rarely seen (003) superlattice peaks, which translated into a high ordering of the L1 0 CoPt superlattice. Such results spur more interest in finding novel classes of nanocomposite magnets based on L1 0 phase.at 675 • C (948 K) does the disorder-order phase transformation take place in CoPt and the strong remanence enhancement effect is due to the multiple phase character of the samples, as it originates from exchange coupling between the face-centered-tetragonal (fct)-ordered hard magnetic phase and the face-centered-cubic (fcc)-disordered soft magnetic matrix.The high ordering temperature is regarded as an obstacle for future utilization of such alloys as the next class of nanocomposite magnets. However, a reduction of the ordering temperature required for L1 0 phase formation can be obtained via suitable modulation of the stoichiometry, for example by adding other elements to the composition. In the case of the FePt system, noble metals such as Au, Ag or Nb have been considered as suitable additions, having the role of promoting early ordering by segregation to the (Fe,Co)Pt grain boundaries [7][8][9][10][11][12][13][14] while a glass-forming element such as boron has been added to FePt to allow synthesis by out-of-equilibrium techniques such as rapid solidification from the melt [15][16][17][18][19][20][21].Chang et al. [22] have studied the effect of Co substitution on the magnetic properties of melt-spun (Fe,Co)-Pt-B nanocomposite ribbons and found that Co substitution enhances the coercivity and energy product due to the formation of ordered L1 0 -(Fe,Co)Pt phase with higher anisotropy field. Makino et al. [23] obtained the crystalline ordered L1 0 -FePt phase, with high coercivity, directly formed by rapid q...

show abstract

2.3.2.2 FePt-based heterocomposites

Djéga‐Mariadassou

2015

Nanocrystalline Materials, Part B

View full text Add to dashboard Cite

Magnetic properties and structure of Fe–Pt–M–B (M=Zr, Nb and Ti) alloys produced by quenching technique

Cited by 11 publications

References 13 publications

Temperature-Dependent Phase Evolution in FePt-Based Nanocomposite Multiple-Phased Magnetic Alloys

Temperature-Dependent Phase Evolution in FePt-Based Nanocomposite Multiple-Phased Magnetic Alloys

Annealing-Induced High Ordering and Coercivity in Novel L10 CoPt-Based Nanocomposite Magnets

2.3.2.2 FePt-based heterocomposites

Contact Info

Product

Resources

About