Alloy Ribbons Research Articles

Interaction of a Ti–Cu Alloy with Carbon: Synthesis of Composites and Model Experiments

Titanium carbide (TiC), is the most thermodynamically stable compound in the Ti–C–Cu system, which makes it a suitable reinforcement phase for copper matrix composites. In this work, the interaction of a Ti–Cu alloy with different forms of carbon was investigated to trace the structural evolution leading to the formation of in-situ TiC–Cu composite structures. The reaction mixtures were prepared from Ti25Cu75 alloy ribbons and carbon black or nanodiamonds to test the possibilities of obtaining fine particles of TiC using ball milling and Spark Plasma Sintering (SPS). It was found that the behavior of the reaction mixtures during ball milling depends on the nature of the carbon source. Model experiments were conducted to observe the outcomes of the diffusion processes at the alloy/carbon interface. It was found that titanium atoms diffuse to the alloy/graphite interface and react with carbon forming a titanium carbide layer, but carbon does not diffuse into the alloy. The diffusion experiments as well as the synthesis by ball milling and SPS indicated that the distribution of TiC particles in the composite structures obtained via reactive solid-state processing of Ti25Cu75+C follows the distribution of carbon particles in the reaction mixtures. This justifies the use of carbon sources that have fine particles to prepare the reaction mixtures as well as efficient dispersion of the carbon component in the alloy–carbon mixture when the goal is to synthesize fine particles of TiC in the copper matrix.

Development of high-coercivity state in melt-spun Fe41Pd41B8Si6P4 ribbons

The phase transformation and magnetic hysteresis properties of melt-spun Fe41Pd41B8Si6P4 ribbons subjected to the annealing at temperatures of 500–550 °C were studied after holding for 0.1–60.0 h by transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermomagnetic analysis. The additions of P, B and Si to the FePd alloy allowed us to achieve the coercivity of 124 kA·m−1, which is 2.6 times higher than that of the melt-spun ribbons of the binary equiatomic FePd alloy. The high-coercivity Fe41Pd41B8Si6P4 alloy is nanocrystalline and is composed of the ordered L10-phase grains approximately 40 nm in size and inclusions of the Fe2(P, B) and Pd2(Si, B) phases. The coercivity kinetics is controlled by the phase transformation which can be divided into three stages: transformation from the bcc structure to nanosized regions of the fcc and Fe2P phases; transformation from the fcc to L10 nanosized regions with somewhat different degrees of tetragonality and their ordering; and extensive growth of the weight fraction of L10 phase from the fcc nanosized regions. P and B atoms occupy interstitial sites in the iron plane of L10 lattice, thus decreasing its Curie temperature (TC).

Microstructure, magnetic and magnetocaloric properties in magnetic-field-induced martensitic transformation Mn1−xCo1+xGe alloy ribbons

The sharp field-induced metamagnetic martensitic transformation plays a pivotal role in magnetoresponsive effects for ferromagnetic shape memory alloys (FSMAs). Homogeneous polycrystalline Mn1−xCo1+xGe alloy ribbons are prepared by using the arc-melting and melt-spinning technique in this work. The microstructure, crystalline structure, magnetic and magnetocaloric properties are studied in these ribbons. The substitution of Co for Mn reduces the structural transformation temperature, which leads to the realization of coincident magnetostructural transformation. Strikingly, a magnetic-field-induced martensitic transformation is observed in these ribbons. Therefore, large magnetocaloric effect, including maximum magnetic entropy change (ΔSM,max) value of ∼28 and 25 Jkg−1K−1 and effective refrigeration capacity (RCeff) of ∼168 and 181 Jkg−1 are obtained for x=0.035 and 0.09 samples, respectively, under the field change of μ0ΔH=0–7T. Furthermore, the average hysteresis loss of these ribbons reduces largely in contrast to their bulk counterparts. These results would provide the new experimental data for magnetic refrigerant materials and pave the way for the further investigation of other FSMAs.

Magnetic-field-induced metamagnetic reverse martensitic transformation and magnetocaloric effect in all-d-metal Ni36.0Co14.0Mn35.7Ti14.3 alloy ribbons

The microstructure, crystalline structure, martensitic transformation, and magnetocaloric effect are systematically studied in all-d-metal Ni36.0Co14.0Mn35.7Ti14.3 alloy ribbons fabricated by melt-spinning technique. Five-layer modulated martensite (5 M) and B2 austenite coexist in both melt-spun and annealed ribbons. Interestingly, all ribbons show a staircase-like magnetic-field-induced metamagnetic reverse martensitic transformation. Accordingly, large magnetocaloric effect near room temperature is obtained, including large magnetic entropy changes of 10 and 13 Jkg−1K−1 and large effective refrigerant capacity of 62 and 63 Jkg-1 under the field change of Δμ0H = 0–2 T, for melt-spun and annealed ribbons, respectively, making the all-d-metal Ni-Mn-based alloy ribbons promising for room temperature magnetic refrigeration.

Significant improvement of soft magnetic properties for Fe-based nanocrystalline alloys by inhibiting surface crystallization via a magnetic field assisted melt-spinning process

Abstract Fe-based soft-magnetic amorphous and nanocrystalline ribbons made with a single-side fast-cooling process always suffer from the surface crystallization which deteriorates the magnetic properties and inhibits the wide applications. In this study, a static magnetic field assisted melt-spinning process was employed to prepare the typical Fe84.75Si2B9P3C0.5Cu0.75 alloy ribbon with an attractive application prospect. According to the comparative investigations of the crystallization behavior, structural evolution process and magnetic properties, it is found that the applied magnetic field can effectively inhibit the formation of compound phases and decrease the size of textured α-Fe grains in the surface layer of the as-spun ribbon. The Fe84.75Si2B9P3C0.5Cu0.75 samples made with low purity raw materials and under an optimal field exhibit superior magnetic properties, including a high saturation magnetization (Bs) over 1.82 T, low coercivity (Hc) of 8.5 A/m, high permeability (μ) of 2.76 × 104 at 1 kHz and much lower losses, after nanocrystallization by annealing. The apparent effect of the applied magnetic field was discussed from the disturbance of a Lorentz force of the fast-moving molten alloy and a magnetic force of preformed grains in a magnetic field during the melt-spinning process. These results provide a novel solution of surface crystallization and an effective route for improving magnetic properties of Fe-based amorphous and nanocrystalline alloy ribbons.

Correlation of composition, cooling rate and superheating temperature with solidification behaviors and microstructures of Al–Bi–Sn ribbons

In this paper, Al85Bi6Sn9, Al75Bi9Sn16, Al60Bi14.4Sn25.6 and Al45Bi19.8Sn35.2 immiscible alloys ribbons were prepared using a single-roller melt-spinning technique. The influences of the composition, the rotating speed of copper roller and the melt superheating temperature were investigated in terms of the thickness, width, phase constitution and microstructures of Al–Bi–Sn ribbons. The results showed that the (Al), (Bi) and (Sn) solid solution phases existed in all the investigated Al–Bi–Sn ribbons. When the rotating speed was larger than 2000 revolutions per minute (rpm), the amorphous phase also was formed. The thickness of ribbons increased and the width decreased with the increase in the aluminum content or with the descent in the melt superheating temperature. The grain sizes of Sn–Bi-rich phase and Al-rich phase decreased gradually with the increases in the rotating speed, the aluminum content or the distance to the free surface. Although there was no obvious macrosegregation under the rapid solidification, the microsegregation still occurred under the rapid solidification. In addition, the grain size of Al75Bi9Sn16 ribbons had a minimum value after the melt superheating treatment at 910 °C. The impact of melt thermal treatment on the microstructure was analyzed from the views of thermodynamics and kinetics. The changes in the grain size and morphology were attributable to the differences in migration rate, solidification rate and the time of liquid-liquid phase separation (L-LPS). The results are conducive for understanding the effects of composition and melt treatment on the microstructures of immiscible alloys.

Recovering the bending ductility of the stress-relieved Fe-based amorphous alloy ribbons by cryogenic thermal cycling

Fe-based amorphous alloys with excellent soft magnetic properties always suffer catastrophic annealing embrittlement. The soft magnetic and mechanical properties of a series of Fe84.3-xCoxSi2B13Cu0.7 (x = 0, 2, 4, 6, 8) amorphous alloy ribbons were investigated. With appropriate substitution of Co for Fe, the BS of the alloys shows a slight increase and the HC remains at a low level. From two-point bending tests, a sharp transition from ductility to brittleness can be observed upon annealing. The embrittlement can be attributed to localized shear bands due to shear bands branching during deformation. It is found that the ductile-brittle transition temperature increases slightly by applying cryogenic thermal cycling treatment to annealed ribbons, indicating that the annealing embrittlement can be improved to some extent by cryogenic thermal cycling treatment. According to nanoindentation results, the increased shear transformation zone volume is responsible for the bending ductility increment. Ultimately, a ductile Fe80.3Co4Si2B13Cu0.7 amorphous alloy ribbons with a BS of 1.68 T and a HC of 4.8 A/m were obtained by cryogenic thermal cycling treatment after annealing.

Martensitic transformation and giant magneto-functional properties in all-d-metal Ni-Co-Mn-Ti alloy ribbons

The all-d-metal Ni50-xCoxMn35Ti15 (x = 13,13.5) ferromagnetic shape memory alloy ribbons are successfully fabricated. The intermartensitic transformation and martensitic transformation arrest phenomenon are systematically investigated. In contrast to melt-spun ribbons, the annealed ribbons reveal an intermartensitic transformation from five-fold (5 M) modulated to non-modulated (L10) martensite below B2→5 M martensitic transformation. The XRD, TEM, DSC and temperature dependence of electrical resistivity measurements validate the occurrence of intermartensitic transformation. On the other hand, the magnetic-field-induced martensitic transformation arrest is achieved in these all-d-metal ribbons like other normal Ni-Mn-based Heusler alloys consisting of p-group and d-group elements. Strikingly, a kinetic de-arrest phenomenon is brought about in all-d-metal ribbons with the increasing heat treatment temperatures. The associated origins are discussed in these ribbons, which is very significant for deeply understanding the arrest and de-arrest phenomenon in ferromagnetic shape memory alloys. What's important, excellent magneto-functional and mechanical properties are obtained in these ribbons. Ni36.5Co13.5Mn35Ti15 annealed ribbon displays the best integrated properties, such as large magnetoresistance (∼34.9%), magnetic entropy change peak value (∼24.9 Jkg−1K−1) and effective refrigerant capacity (∼122.5 Jkg−1) under the field change of Δμ0H = 0–5 T, and large Vickers hardness [2.75 GPa (280.7HV)]. These make the all-d-metal Ni-Mn-based Heusler alloy ribbons attractive in the practical applications.

Effect of additions of phosphorous, boron, and silicon on the structure and magnetic properties of the melt-spun FePd ribbons

Abstract Formation of the L10 structure in FePd alloys doped with nonmetallic elements is studied on melt-spun and annealed samples. The melt-spun Fe41Pd41P18−x−yBxSiy (x = 0–14; y = 0, 6) ribbons were annealed at the temperatures of 400–650 °C for different holdings in the range from 5 min to several hours and studied by X-ray and thermomagnetic analysis and TEM. The saturation magnetization, Curie temperature of the L10 phase, and grain size of the melt-spun doped Fe41Pd41P18−x−yBxSiy ribbons decrease in comparison with those of the melt-spun binary FePd alloy. The refined grain structure results in enhancing coercivity. Among all as-annealed samples, the P addition favors the amorphization of the as-spun Fe41Pd41P18 ribbons and refines grains of the formed L10 phase, but decreases magnetization. Substitution of B for P gives rise to magnetization of the Fe41Pd41P18−x−yBx alloys, but decreases their coercivity. A partial substitution of Si for B at the same P content refines grains and enhances the coercivity without a decrease in the magnetization of the Fe41Pd41P4B8Si6 alloy. It is suggested that P and B atoms occupy interstitial sites in the L10 lattice in the iron plane, weakening the exchange interaction and decreasing the Curie temperature. The additions of P, B, and Si to the FePd alloy allowed us to obtain the Fe41Pd41P4B8Si6 ribbons with the coercivity of 1560 Oe, which is 2.6 times higher than that of the melt-spun ribbons of the FePd alloy.

FeNbBP type nanocrystalline alloy with high B s of 1.64 T optimized by sputtered thin film method

The increasing of saturation magnetic flux density (Bs) in FeNbB type nanocrystalline alloy has been widely studied. The influence of additional element to improve Amorphous Forming Ability (AFA) in precursor was investigated using substrate temperature controlled sputtering method at 523K. The AFA was improved by the addition of P, Si, V, or Mo, was decreased by the addition of Y, Cu, or Ge. Especially, the addition of 1 at% P exhibited a good effect of obtaining 85 at% of maximum Fe content with high stable amorphous precursor. The addition of P or C increased Bs. The Fe85Nb6B8P1 nanocrystalline alloy ribbon showed stable amorphous phase as quenched, exhibited a homogeneous nanocrystalline structure composed of grains with 10 to 20 nm in diameter after nanocrystallization. The ribbon exhibited high Bs of 1.64T and low coercivity of 10 A/m.

Transport properties of ferrimagnetic Mn2CoSn Heusler alloy

Abstract Transport properties of bulk samples and melt-spun ribbons of Mn2CoSn alloy were investigated. It was found that Mn2CoSn is a high-resistance compound with the value of electrical resistivity ρ ∼ 300 μOhm·cm at room temperature and demonstrates semiconducting behavior of ρ as a function of temperature. A change in the dominating conductivity type from hole-like to electron-like takes place upon heating above ≈137 K. Abnormal Hall coefficient RS is large and depends on electrical resistivity as RS ∼ ρ2.

Glass-Forming Ability, Thermal Stability, and Hardness of Rapidly Solidified Al-Ni-Y-Sc Alloy Ribbons and Rods

The crystallization behaviors and thermal stability of (Al87Y8Ni5)100−xScx (x = 0, 1.0, 1.5) amorphous ribbons and alloy rods, produced by roller melt-spinning method and inductance casting, were investigated mainly by x-ray diffractometry (XRD) and differential scanning calorimetry (DSC). The glass transition temperatures of the (Al87Y8Ni5)99.0Sc1.0 and (Al87Y8Ni5)98.5Sc1.5 alloy ribbons were found to be 201 and 197 °C, respectively. Furthermore, the melting temperatures of the alloy ribbons decreased with the Sc content. This revealed that the glass-forming ability (GFA) of the metallic glass increased with increasing Sc content. Crystallization of (Al87Y8Ni5)100−xScx (x = 0, 1.0, 1.5) amorphous ribbons occurred in the temperature range of 200 to 400 °C in three exothermic reaction stages. The peak temperatures of these three crystallization reactions shifted to higher temperatures at higher heating rates. The kinetic parameters for the first crystallization reaction, determined by Kissinger method, revealed that adding 1.5 at.% Sc increased the activation energy for crystallization from 158 to 167 kJ/mol. On the other hand, the cross-section morphology of the three different alloys revealed that a fully amorphous outer region and a partially crystallized core region formed in each alloy rod. It was also found that the thickness of the amorphous region increased with the Sc content, revealing a positive effect of Sc on the GFA.

Structure and Magnetic Properties of Amorphous Fe-Zr-Nb-Cu-B-(Y) Ribons

In this paper the results of the structural and magnetic properties for amorphous alloys ribbons Fe86Zr7Nb1Cu1B5 and Fe86Zr4Y3Nb1Cu1B5 were presented. From X-ray diffraction and M�ssbauer investigations we have stated that amorphous ribbons were fully amorphous. The investigated alloys, exhibit poor soft magnetic properties at room temperature. However, at low temperatures they show relatively large magnetic susceptibility and good its time stability.

Effect of Adding Co on Crystallization Behavior and Magnetoimpedance Effect of Amorphous/Nanocrystalline FeCuNbSiB Alloy Strips

After one of the B atoms in Fe73.5Cu1Nb3Si13.5B9 alloy was replaced by both 0.7 Si and 0.3 Co, Fe73.5Co0.3Cu1Nb3Si14.2B8 alloy ribbons were prepared by single roll fast quenching method. The obtained alloy ribbons were subsequently wound into ring magnetic cores, and then these magnetic cores were annealed at different temperatures in air. The effects of adding Co on the crystallization behavior and soft magnetic properties of the as-quenched alloy ribbons with and without heat treatment were studied. The results show that the amorphous structure of the prepared Fe73.5Co0.3Cu1Nb3Si14.2B8 alloy ribbons is transformed into the coexistence of amorphous and nanocrystalline structures after heat treatment at 550°C. Comparing with Fe73.5Cu1Nb3Si13.5B9 alloy ribbons, the first initial crystallization temperature (Tx1) and crystallization peak temperature (Tp1) of Fe73.5Co0.3Cu1Nb3Si14.2B8 alloy ribbons were reduced by 1.6 and 1.7°C, respectively, While the second initial crystallization temperature (Tx1) and crystallization peak temperature (Tp2) were increased by 6.5 and 5.7°C, respectively, resulting in that the difference between the first and the second initial crystallization temperatures (∆Tx) are increased by 8.1°C; the initial permeability (μi) and saturation induction density (Bs) of the amorphous/nanocrystalline Fe73.5Co0.3Cu1Nb3Si14.2B8 magnetic cores were reduced by 0.15 H/m and 0.39 T, respectively, while the coercivity (Hc) is increased by 0.34 A/m.

The Evolution of Phase Constitution and Magnetic Properties of the Annealed Pr-Fe-B-W Alloy Ribbons

The Evolution of Phase Constitution and Magnetic Properties of the Annealed Pr-Fe-B-W Alloy Ribbons

Crystallization Studies of Hard Magnetic Pr9Fe56Co13Zr1Ti3B18 Alloys Ribbons of Various Thicknesses

Crystallization Studies of Hard Magnetic Pr₉Fe₅₆Co₁₃Zr₁Ti₃B₁₈ Alloys Ribbons of Various Thicknesses

Effect of Co addition and annealing conditions on the magnetic properties of nanocrystalline FeCoSiBPCu ribbons

Abstract We report the effect of substituting Co for a metalloid element on the glass formation, thermal properties, and magnetic behaviors of Fe80CoxB14−xSi2P3Cu1 (x = 0, 2, 4, 6) alloy ribbons. The addition of Co decreased the thermal stability of the alloy against crystallization and expanded the heat treatment temperature region of this alloy family. Fe80Co4B10Si2P3Cu1 alloy, which was annealed under optimal conditions, exhibited good soft magnetic performance that was characterized by a high saturation magnetic flux density of 1.84 T, a high effective magnetic conductivity of 12,601 at 1000 Hz, a low coercivity of 5.3 A/m, and a low core loss of 62 W/kg at 1000 Hz and 1.5 T.

Microstructure and magnetocaloric effects of Mn1.2Fe0.8P0.6Si0.4B0.05 alloys prepared by ball milling and spinning methods

Abstract The Mn1.2Fe0.8P0.6Si0.4B0.05 alloys were prepared by ball milling and melt-spinning methods. The structure and magnetic characteristics of all samples were examined by X-ray diffraction, vibrating sample magnetometer and SEM. Results show that both the ribbon and bulk alloys can crystallize in a hexagonal Fe2P-type phase with some impurity phase. The lattice parameters, a and c, of Fe2P-type phase are 6.02960 A, 6.03033 A, and 3.42310 A, 3.44431 A for ribbon and bulk Mn1.2Fe0.8P0.6Si0.4B0.05 alloys, respectively. The Curie temperature increased by 20% from 165 K in bulk to 197 K in ribbon while thermal hysteresis and magnetic hysteresis decreased by 28% and 80% for ribbon sample, respectively. Moreover, the values of magnetic entropy change can be tuned from 15.7 J⋅kg−1⋅K−1 in bulk to 21.8 J⋅kg−1⋅K−1 in ribbon under 0–5 T, resulting in the effective refrigerant capacity (RCE) increasing from 238 to 286 J⋅kg−1. The nature of the phase transitions was studied through the Arrott plots, indicating that the samples undergo first-order ferro-paramagnetic phase transitions. The origin of magnetic hysteresis losses is also discussed deeply. Furthermore, this alloys with large magnetic entropy change could be an interest potential for future magnetic refrigeration applications.

Microstructure and magnetic properties of Nd-Fe-B sintered magnet by diffusing Pr-Cu-Al and Pr-Tb-Cu-Al alloys

Abstract Grain boundary diffusion process (GBDP) with low melting-point alloy ribbons, namely Pr70Cu15Al15 (PCA), Pr65Tb5Cu15Al15 (PTCA-5) and Pr50Tb20Cu15Al15 (PTCA-20, at%), was applied to Nd-Fe-B sintered magnet (52 M) as thick as 6 mm. The coercivities of diffused magnets by PCA, PTCA-5 and PTCA-20 increase significantly to 19.6 kOe, 24.1 kOe and 24.3 kOe, respectively, from original 14.7 kOe. Microstructural investigations indicate that the coercivity enhancement of PCA magnet is mainly attributed to magnetic isolation by continuous Nd-rich grain boundary phases (GBP). However, the coercivity enhancement of PTCA-20 magnet is mainly owing to magnetic hardening by Tb-rich shells (TRS), and that of PTCA-5 magnet results from a combined strengthening of magnetic isolation by GBP and magnetic hardening by TRS. Meanwhile, the coercivity of PTCA-5 magnet is as high as that of PTCA-20 magnet, but the former consumes Tb only 0.60 wt%, lower than 1.23 wt% for the latter.

Characterization of brazed joints by electrical resistance spot brazing with Ni-based amorphous self-flux alloys

In this study the behavior of brazing joints with nickel-silicon-based amorphous alloys ribbons was analyzed in terms of mechanical strength and corrosion resistance. Two Ni78Si8B15 and Ni68Fe3Cr7Si8B14 metallic glasses ribbons designed and fabricated in our laboratory have been studied as brazing foils. The base material of the joint is the 316L austenitic stainless steel. Note that the two tested chemical compositions of the ribbons are recommended for brazing stainless steels. A comparison between brazed joints and welded steel by electrical resistance spot has also been conducted.As results, Ni78Si8B15 amorphous alloy presents a very good castability, wettability and flowability. However the addition of chromium and iron to form Ni68Fe3Cr7Si8B14 significantly increases the melting temperature, the corrosion resistance and the mechanical strength. Finally we found that the brazed joint with Ni68Fe3Cr7Si8B14 metallic glasses ribbon has the same yield strength than that of the welded joint, but it presents a better corrosion resistance.