As-spun Ribbons Research Articles

Effect of Mischmetal Addition on Physical and Mechanical Properties of Al–Ni–Zr Melt-Spun Ribbons

In this work, the effect of mischmetal addition on the microstructural, physical and mechanical properties of rapidly solidified (Al90Ni8Zr2)(100−x)MMx (x = 0–6) alloys has been studied. In this respect, various as-spun ribbons were prepared by the single-roller melt-spinning process at a quenching wheel speed of 43 m/s. The results obtained showed that mischmetal had a strong effect on the control of amorphicity of the alloy during melt-spinning process. TEM and XRD results revealed the presence of two phases, nanocrystalline α-Al and amorphous phase of Al90Ni8Zr2 alloy compared with those of MM-added samples with an amorphous structure. This is believed to be related to the increase in glass-forming ability due to the addition of mischmetals to the alloy. The average crystallite size obtained for MM-free sample was in the range of 30 nm as confirmed by XRD and TEM data. Phase separation and formation of second phase were observed for 6 at.% MM-added sample in the as-spun state. DSC results revealed that glass transition and crystallization temperatures increased with the increase in mischmetal in Al90Ni8Zr2 system. Further, it was seen that the maximum microhardness value was obtained for the 4 at.% MM-added samples (4.72 GPa).

Microstructure and properties of cost-effective Fe–6.5 wt% Si ribbons fabricated by melt-spinning

Melt-spinning was successfully used to fabricate continuous Fe–6.5wt.%Si ribbons of 35 μm in thickness and 50–60 mm in width. Equiaxed grains measuring 2.4 ± 1.0 μm and columnar grains measuring 1.69 ± 0.72 μm were observed on the wheel and free surfaces, respectively. The as-spun ribbons showed strong 〈100〉 fiber texture, excellent room-temperature ductility, and very low core losses at high frequencies above 10 kHz. Compared with other fabricating techniques, the present work verified the feasibility for melt-spinning technique to fabricate ribbons of Fe–6.5 wt%Si with large-scale and thus cost-effective.

Chemically dealloyed Fe-based metallic glass with void channels-like architecture for highly enhanced peroxymonosulfate activation in catalysis

Metallic glasses (MGs) with their intrinsic disordered atomic structure and widely controllable atomic components have recently emerged as fascinating functional materials in wastewater treatment. Compared to crystalline alloys, the less-noble atomic components in monolithic metallic glass are more efficient to be selectively dissolved during dealloying process. This work reported a facile chemical dealloying approach to fabricate a void channels-like structured MG with the elemental components of Fe73.5Si13.5B9Cu1Nb3 for methylene blue (MB) degradation. Results indicated that the dealloyed Fe73.5Si13.5B9Cu1Nb3 MGs with the void channels-like morphology presented a significant improvement of catalytic efficiency and reusability. The dye degradation reaction rate (kobs) of the dealloyed Fe73.5Si13.5B9Cu1Nb3 MGs presented 3 times higher than their as-spun MGs. More importantly, the dealloyed Fe73.5Si13.5B9Cu1Nb3 MGs can be reused up to 25 times without significantly loosing catalytic efficiency. It was also found that the dealloyed Fe73.5Si13.5B9Cu1Nb3 MGs exhibited a greater corrosion resistance in the simulated dye solution compared to the as-spun ribbons, demonstrating a robust self-healing ability in catalytic activity. This work provides a novel view for designing MG catalysts with high efficiency and stability in worldwide energy and environmental concerns.

Structural and magnetic properties of nanocrystalline Zr-Co-Nb-Si-B rare earth free permanent magnets fabricated by spark plasma sintering

Abstract Rare earth free nanocrystalline Zr16Co78-xNbxSi3B3 (x = 0–3) bulk magnets were fabricated from melt spun ribbons with high density by employing spark plasma sintering (SPS) technique. The effect of SPS temperature on structural and magnetic properties was investigated. The hard magnetic Zr2Co11 phase which was present in the as-spun ribbons retained after SPS, indicating no phase decomposition. The magnetic properties were found to depend on consolidation temperature and Nb concentration. Optimum magnetic properties of coercivity of 3.3 kOe with saturation magnetization of 52 emu/g were obtained for x = 1 magnet consolidated at 600 °C. SPS magnets display a moderate magnetic texture and the coercivity mechanism is governed by combination of both domain wall pinning and nucleation of reverse domains.

Microstructural Evolution of Brazed Ti-joint Using Ti20Zr20Cu50Ni10 Metallic Glass Ribbon as Filler

Metallic glasses of Ti20Zr20Cu50Ni10 in the form of hard ribbon were produced by the standard melt-spinning technique on copper roller wheel in air. Vacuum brazing using these ribbons were done to join two plates of Ti alloy at 990 K for a period of 10 min. The main aim of the present work was to study the use of the metallic glass ribbons as brazing material for titanium based alloys. Since the microstructure during crystallization of these metallic glasses is expected to influence the strength of brazing joints, microstructure characterization is very important. Here we present the results of characterization of the ribbons with Ti20Zr20Cu50Ni10 composition as well as the brazed sample after joining two Ti-plates. Both as-spun and heat-treated ribbon were characterized by X-ray Diffractometry (XRD), Field-Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM) and the energy dispersive X-ray spectroscopy (EDX) attached to both TEM and FESEM. The as-prepared ribbons showed amorphous nature when examined on both surfaces by XRD and as was also verified by TEM study of heat treated (753 K, 30 min.) ribbon showed formation of nanocrystalline microstructure comprised of equi-axed grains having sizes in the range of about 50-200 nm. Electron diffraction analysis in the TEM suggested the presence of two phases, viz., cubic Ti2Ni and (Ti, Zr)2Ni phases.

Crystallization progress and soft magnetic properties of FeGaBNbCu alloys

Abstract Fe81−xGaxB15Nb3Cu1 (x = 0, 3, 6, 9, 12 at%) ribbons were fabricated by using melt-spun method and their crystallization kinetics, magnetic properties and microstructure were investigated. We found that the small quenched-in Fe–Ga clusters were formed in the as-spun ribbons with Ga addition. Besides, proper Ga addition could suppress the precipitation of Fe2B phase. During annealing, addition of Ga could provide Fe–Ga clusters to be nucleation sites for the α-Fe(Ga) phase, and could inhibit the initial grain growth. With the increase of annealing temperature above 475 °C, the crystallization was controlled by both Fe–Ga and Cu clusters, which effectively refined the grain size by facilitating the nucleation and increased the crystallization volume fraction. Consequently, in the ribbon with 6 at% Ga, the grains turned out to be the minimum in the mean size of 8 nm, and the optimal soft magnetic properties with coercivity at 6.8 A/m and saturation magnetization at 167 emu/g were obtained at annealing temperature of 490 °C for 3 min.

Studies on the structure and magnetic properties of Sm8Co73.2Fe8.8B10 ribbons

The Sm8Co73.2Fe8.8B10 ribbons were prepared by melt-spinning at a roller velocity of 40 m/s followed by annealing at 700–900 °C for 30 min, and then their structure and magnetic properties were studied. The results show that the as-spun ribbons are composed of Sm(Co,Fe)12B6 and Sm2(Co,Fe)14B nanocrystallines with an average size of ∼10 nm distributed on the amorphous matrix, and exhibit the weak hard magnetic properties. Moreover, the annealing treatment at 800 °C can obviously improve the ones, and make the ribbons consist of Sm(Co,Fe)12B6, Sm2(Co,Fe)14B, Sm2(Co,Fe)7, Co0.72Fe0.28 and a little residual amorphous phase. However, a higher annealing temperature of 900 °C will reduce the comprehensive magnetic properties of ribbons due to the changes in microstructure. The Curie temperatures of Sm(Co,Fe)12B6, Sm2(Co,Fe)14B, Co0.72Fe0.28 phases are -(103–120) °C, 770–780 °C and 900 °C, respectively. The relationship between microstructure and magnetic properties was discussed in detail and the microstructural model was proposed to determine the magnetic properties.

Solidification Rate Dependence of Microstructures and Transformation Behavior of Ti-Ni-Hf Alloys.

The microstructures and transformation behavior of Ti-49Ni-20Hf, Ti-49.5Ni-20Hf and Ti-50.3Ni- 20Hf alloys, when prepared by conventional casting, were investigated and compared with the properties of the alloys prepared by melt spinning. The area fraction of (Ti,Hf)2Ni in Ti-Ni-Hf alloys decreased to 3.9% from 9.4% as Ni content rose to 50.3 at% from 49 at%. Several cracks were observed in the hot-rolled Ti-49Ni-20Hf alloy sheet but none were found in the Ti-50.3Ni-20Hf alloy sheet. The B2-B19' transformation start temperature (Ms) decreased to 476 K from 580 K as Ni content increased to 50.3 at% from 49 at%. All the as-spun ribbons were amorphous, and the activation energy for crystallization ranged from 167.8 kJ/mol to 182.7 kJ/mol based on Ni content. When annealing temperature ranged from 810 K to 873 K, crystalline Ti-Ni-Hf alloys without (Ti,Hf)2Ni particles were obtained. At annealing temperatures higher than 873 K, very fine (Ti,Hf)2Ni particles, less than 20 nm in size, were found embedded in a crystalline matrix.

Effect of heat treatments on crystallization behavior, thermal ability and magnetic properties of Fe85Si1.4B9P4Cu0.5C0.1 amorphous alloy

The influence of heat treatments on the crystallization behavior and magnetic properties of Fe85Si1.4B9Cu0.5P4C0.1 amorphous alloy were investigated. The as-spun ribbon was annealed at various temperatures for different time in nitrogen atmosphere. It indicates that both of annealing temperatures and time have an important influence on the formation of nanocrystalline structure. Through a series of heat treatments, it found that the rapid thermal processing could effectively prevent the precipitation of Fe-(B, P) compounds and reduce the Hc of alloy. Before the precipitation of secondary phases, the increase of annealing time is effective for the precipitation of a large number of α-Fe phases, which contributes to the increase of saturation magnetization (Ms) of the alloy. The Fe85Si1.4B9Cu0.5P4C0.1 nanocrystalline alloy annealed at 420 °C for 1 min exhibits lowest Hc of 5.5 A/m and higher Ms. of 204.5 emu/g (Bs ≈ 1.92 T). The Fe85Si1.4B9Cu0.5P4C0.1 nanocrystalline alloy annealed at 420 °C for 30 min exhibits highest Ms. of 207.9 emu/g (Bs ≈ 1.95 T) and lower Hc of 6.7 A/m.

Structural Properties of brazed Ti joint using Ti20Zr20Cu40Ni20 metallic glass ribbon as filler

In the present investigation, we present our results on characterization of Ti joints, brazed with metallic glass ribbons of Ti20Zr20Cu40Ni20 alloy. Initially, metallic glass ribbons were produced using a vacuum melt spinner and used as filler materials for vacuum brazing of two Ti alloy plates at 967 °C for period of 10 min. Field-Emission Scanning Electron Microscopy (FESEM), the as-spun ribbons showed fully amorphous structure when examined on both surfaces by XRD and also verified by TEM investigation. The brazing joint of two Ti-plates using the metallic glass ribbon was found to be very sound. FESEM characterization of the cross-sectioned brazing joint shows sub-micron size grains uniformly distributed in the matrix with brighter appearance. EDX analysis revealed that the sub-micron grains are rich in Ti, while the matrix phase has Zr-enrichment. Back Scattered Electron (BSE) image also suggested substantial reaction of the brazing ribbon with Ti plates, whose typical lath microstructure is modified to nanostructured lamellar eutectic microstructure comprising of Ti-rich and Zr-enriched phases.

Microstructure, magnetic properties and cryogenic magnetocaloric effect in Cu20Al20Er60 amorphous ribbons

The glass forming ability, microstructure as well as the cryogenic magnetic and magnetocaloric properties in melt-spun Cu20Al20Er60 ribbons were reported. The as-spun ribbons were confirmed to possess fully amorphous structure with a large supercooled liquid region of 54.3 K. A broad second-order paramagnetic to ferromagnetic (PM-FM) magnetic transition together with a large reversible cryogenic magnetocaloric effect (MCE) in Cu20Al20Er60 amorphous ribbon was found around TC of 13.3 K. The MCE parameters of the maximum magnetic entropy change (−ΔSMmax), relative cooling power (RCP) and refrigerant capacity (RC) for Cu20Al20Er60 amorphous ribbons were evaluated to be 15.3 J/kg K, 543 J/kg and 420 J/kg for a magnetic field change (ΔH) of 0–7 T, respectively.

Effect of heat treatment procedure on magnetic and magnetocaloric properties of Ni43Mn46In11 melt spun ribbons

The effect of heat treatment on the structural, magnetic and magnetocaloric properties of Ni43Mn46In11 melt-spun ribbons was systematically investigated using X-ray powder diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), magnetic force microscope (MFM) and magnetic measurements. From the XRD studies, tetragonal and cubic phases were detected at room temperature for as-spun, quenched and slow-cooled ribbons. Furthermore, it was observed, upon annealing martensite transition temperatures increased when compared to the as-spun ribbon. To avoid magnetic hysteresis losses in the vicinity of the structural transition region, the magnetic entropy changes-ΔSm of the investigated ribbons were evaluated from temperature-dependent magnetisation-M(T) curves on cooling for different applied magnetic fields. The maximum ΔSm value was found to be 6.79 J kg−1 K−1 for the quenched ribbon in the vicinity of structural transition region for a magnetic field change of 50 kOe.

A new Sm(Co,Fe,Cu)4B/Sm2(Co,Fe,Cu)7 cell structure with the coercivity of up to 5.01 T

A new Sm(Co,Fe,Cu)4B/Sm2(Co,Fe,Cu)7 cell structure is found, and its phase composition, microstructure and magnetic properties are investigated. Particularly, the atom structure of main phase is analyzed by extended X-ray absorption fine structure. It was found that as-spun SmCo2.94FeCu0.06B ribbons were composed of amorphous phase and approximate equiaxed Sm(Co,Fe,Cu)4B nanocrystallines. The high disorder of the nanocrystallines leads to the low magnetic anisotropy. After the as-spun ribbons were annealed at 800 °C for 30 min, the amorphous phase disappeared completely. The short rod-shaped Sm(Co,Fe,Cu)4B grains have a staggered distribution accompanied by ∼8 vol% lamellar Sm2(Co,Fe,Cu)7 phase at grain boundaries, and the new cell/cell-wall-type Sm(Co,Fe,Cu)4B/Sm2(Co,Fe,Cu)7 microstructure is produced. The annealed ribbons show an ultra-high coercivity of up to 5.01 T at room temperature, 40.64 T at 5 K (obtained by extrapolating), and estimated to be ∼ 41.96 T at 0 K. The microstructureal models of both ribbons are created and the coercivity mechanism is discussed in detail.

Study on Magnetic and Corrosion Properties of Ce<sub>16</sub>Fe<sub>95-x</sub>Co<sub>x</sub>B<sub>8</sub> (x=0-4) Alloys

To understand the phase composition and improve the magnetic performances of Ce2Fe14B-type alloys, the ribbons of Ce16Fe95-xCoxB8(x=0-4.0) were prepared by melt-spinning at a quench wheel velocity of 40 m/s. The phase composition and magnetic properties of Ce16Fe95-xCoxB8(x=0-4.0) alloys were investigated. XRD results indicated that the main phase existed in the as-spun ribbons is Ce2Fe14B. The amorphous formation ability and thermal stability of as-spun ribbons were enhanced by trace cobalt addition. Co-doped samples had higher Curie temperature compared with bare Ce2Fe14B, which signified that Co atoms could substitute for Fe directly into Ce2Fe14B phase. The corrosion potential of alloys from-1089mV (vs. SCE) to-1077mV (vs. SCE) which indicated that the Co-doped provided better corrosion protection properties for the Ce-Fe-B magnet compared with bare substrate.

Study of Structure and Magnetic Properties of SmCo10 Alloy Prepared by Different Methods

In this paper, the phase compositions, microstructures, atomic structures, and magnetic properties of Co‐rich SmCo10 alloys prepared by arc‐melting, annealing, and melt‐spinning were studied. It was found that as‐cast alloy is composed of Th2Zn17‐type Sm2Co17 matrix with an average grain size of ∼45 μm accompanied by lamellar eutecticum (consisting of α‐Co and Th2Zn17‐type Sm2Co17) distributed at grain boundaries. The annealed alloy has the same phase composition and phase distribution as the as‐cast alloy except that the average grain size decreases to ∼35 μm, and the eutecticum has more homogeneous distribution on the matrix. Simultaneously, the atomic structure of Sm2Co17 is unchanged with only a decrease in structural disorder after annealing. The as‐spun ribbons are composed of ∼95.5 vol.% TbCu7‐type Sm2Co17 and the rest α‐Co. The short rod‐shaped α‐Co grains are intermittently distributed at the grain boundaries of equiaxed Sm2Co17 grains. The as‐spun ribbons show a higher coercivity, and the annealed alloy shows maximum magnetization. The structural parameters were calculated by Extended X‐ray Absorption Fine Structure (EXAFS), and the relationship between structure and magnetic properties was discussed in detail.

Microstructural Characterization of Ti<sub>20</sub>Zr<sub>20</sub>Cu<sub>40</sub>Ni<sub>20</sub> Metallic Glass

In the present investigation, we present our results on characterization of Ti joints, brazed with metallic glass ribbons of Ti20Zr20Cu40Ni20 alloy. Initially, metallic glass ribbons were produced using a vacuum melt spinner and used as filler materials for vacuum brazing of two Ti alloy plates at 1270 K. Field-Emission Scanning Electron Microscopy (FESEM), the as-spun ribbons showed fully amorphous structure when examined on both surfaces by XRD and also verified by TEM investigation. The detailed DSC results revealed that the amorphous phase crystallized at approximately 753K. The brazing joint of two Ti-plates using the metallic glass ribbon was found to be very sound. FESEM characterization of the cross-sectioned brazing joint shows sub-micron size grains uniformly distributed in the matrix with brighter appearance. EDX analysis revealed that the sub-micron grains are rich in Ti, while the matrix phase has Zr-enrichment. Back Scattered Electron (BSE) image also suggested substantial reaction of the brazing ribbon with Ti plates, whose typical lath microstructure is modified to nanostructured lamellar eutectic microstructure comprising of Ti-rich and Zr-enriched phases.

A new tetragonal phase in CoFeCrGe Heusler alloy

CoFeCrGe ribbons were prepared by melt spinning and then annealed at 300°C for 4h and 500°C for 4h, respectively. The as-spun ribbons of CoFeCrGe have the B2 type structure with a=0.287nm. The CoFeCrGe ribbons annealed at 300°C are composed mainly of the L21 type structure with a=0.578nm in partial disorder and the B2 type structure with a=0.289nm in further disorder case. The ribbons annealed at 500°C are composed of three compounds with average compositions of Co26.0Fe26.5Cr23.5Ge24.0, Co3.8Fe6.4Cr68.5Ge21.3 and Co53.4Fe30.4Cr8.6Ge7.6, listed in a sequence of volume percentage from major to minor. The primary compound Co26.0Fe26.5Cr23.5Ge24.0 is the L21-type structure with a=0.571nm in partial disorder and the B2 type structure with a=0.286nm in further disorder case. The secondary compound Co3.8Fe6.4Cr68.5Ge21.3 has a cubic Cr3Ge structure with a=0.461nm. The tertiary compound Co53.4Fe30.4Cr8.6Ge7.6 is a new tetragonal structure with lattice parameters a=0.76nm, c=0.284nm, which were determined by using tilt-series electron diffraction technique in this work. The tertiary (Co, Fe)-rich phase is usually embedded in the matrix of the secondary Cr-rich phase, but there is no special orientation between the two phases. The difference in the magnetic hysteresis loops of the samples annealed at 300°C and 500°C has been interpreted as the appearance of the new tetragonal crystalline phase. Element doping is the possible way for further developing the single tetragonal phase or increasing the amount of this phase.

Effects of Microwave-Assisted Annealing on the Structure and Magnetic Properties of (Nd0.75Pr0.25)9Fe72Ti1Zr3Mn x Mo4−x B10.5C0.5 Amorphous Ribbons

The amorphous as-spun ribbons with nominal composition (Nd0.75Pr0.25)9Fe72Ti1Zr3Mn x Mo4−x B10.5C0.5(x = 1, 2, 3) were annealed by microwave-assisted annealing. The effects of the Mn-doped alloys on glass-forming ability (GFA), crystallization, and magnetic properties of the Nd2Fe14B/α-Fe nanocomposite magnets were examined by thermal differential scanning calorimetry (DSC), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). An appropriate amount of Mn was beneficial to the optimization of the structure and magnetic properties. Compared with conventional annealing, the microwave-assisted annealing has contributed to the precipitation of hard magnetic phases and adjusted the proportion of hard and soft magnetic phases. The optimum magnetic properties with coercivity up to 805 kA/m were found for ribbons (with composition x = 1) annealed under the microwave power of 2000 W for 10 min.

Structure and magnetic properties of Alnico ribbons

Al-Ni-Co alloy has been widely applied in various industrial fields due to its excellent thermal and magnetic stability. In this paper, new Al-Ni-Co ribbons are prepared by simple processes combining melt-spinning with annealing, and their phase transition, microstructure and magnetic properties are studied. The results show that after as-spun ribbons are annealed, the grain size of ribbons increases from 1.1 ± 0.3 μm to 4.8 ± 0.8 μm, but still much smaller than that of the bulk Al-Ni-Co alloy manufactured by traditional technologies. In addition, some rod-like Al70Co20Ni10-type, Al9Co2-type and Fe2Nb-type phases are precipitated at grain boundaries; simultaneously, the distinct spinodal decomposition microstructure with periodic ingredient variation is thoroughly formed in all grains by the reaction of α → α1 + α2. Furthermore, the α1 and α2 distribute alternately like a maze, the Fe-Co-rich α1 phase holds 35.9–47.3 vol%, while the Al-Ni-rich α2 phase occupies the rest. Finally, the coercivity of annealed ribbons can reach to 485.3 ± 76.6 Oe. If the annealed ribbons are further aged at 560 °C, their Hc even increases to 738.1 ± 81.0 Oe. The coercivity mechanism is discussed by the combination of microstructure and domain structure.

Effects of Cu Addition on Magnetic Properties and Microstructures of Annealed Zr–Co–Cu–B Ribbons

The magnetic properties and microstructures of Zr18Co82− x Cu x B2 ( $x = 0$ , 1, 2, 3, and 4) ribbons fabricated by melt-spinning technique were investigated to analyze the effects of Cu addition on the stabilization of a hard magnetic rhombohedral Zr2Co11 phase. In as-spun ribbons, the proportion of the rhombohedral Zr2Co11 phase increased up to $x = 3$ . In addition, it was found that the Cu addition inhibited the decomposition of the rhombohedral Zr2Co11 phase into Co and ZrCo5 phases during the post-annealing process. In particular, annealed Zr18Co79Cu3B2 ribbons showed that the recrystallized grains having rhombohedral Zr2Co11 phase were grown as aligned rod-shaped grains with lengths of 200 nm. Thus, the Cu addition increased the coercivity of both as-spun and annealed ribbons. A maximum coercivity of 4.7 kOe was obtained in Zr18Co80Cu2B2 ribbons annealed at 550 °C.