As-spun State Research Articles

The Effects of Si Substitution with C on the Amorphous Forming Ability, Thermal Stability, and Magnetic Properties of an FeSiBPC Amorphous Alloy

The industrialization of Fe-based amorphous alloys with high a saturation magnetic flux density (Bs) has been limited so far due to their inadequate amorphous forming ability (AFA). In this study, the effects of substituting Si with C on the AFA, thermal stability, and magnetic properties of Fe82Si6−xB9P3Cx (x = 0–6) alloys were systematically investigated. The experimental results demonstrate that the AFA, thermal stability, and soft magnetic properties can be significantly enhanced by the addition of C. Specifically, at a copper wheel velocity of 40 m/s, the Fe82Si6−xB9P3Cx (x = 2, 3, 4, 5 and 6) alloy ribbons exhibit a fully amorphous structure in the as-spun state. The activation energy required for the α-Fe phase crystallization process in Fe82Si6−xB9P3Cx (x = 0, 2, 4, and 6) alloys is determined to be 326.74, 390.69, 441.06, and 183.87 kJ/mol, respectively. Among all of the compositions studied, the Fe82Si4B9P3C2 alloy exhibits optimized soft magnetic properties, including a low coercivity (Hc) of 1.7 A/m, a high effective permeability (μe) of 10608 (f = 1 kHz), and a relatively high Bs of 1.61 T. These improvements may be attributed to a more homogeneous and optimized magnetic domain structure being achieved through proper C addition. This work holds significant implications for the advancement of Fe-based soft magnetic amorphous alloys with high Bs.

Microstructural characterization of rapidly solidified Al-13.5 at.% Cr and Al-13.5 at.% V alloys for catalytic applications

Intermetallic compounds, due to their well-defined stoichiometry, arrangement of atoms and controlled crystal structure, are a promising alternative to expensive noble metal catalysts. In this paper, the catalytic properties of Al-13.5 at.% Cr and Al-13.5 at.% V alloys, corresponding to the quasicrystalline approximants Al45Cr7 and Al45V7, were investigated for the first time.The alloys in the form of fragmented brittle ribbons were produced by the melt-spinning. The microstructure of the ribbons, both in the as-spun state and after heat treatment (100 h at 600 °C), was characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. In the as-spun state, the ribbons showed a multiphase microstructure. In addition to the Al45Cr7 phase in the Al-Cr alloy and the Al3V phase in the Al-V alloy, they also contained α(Al) solid solution and icosahedral quasicrystalline phases. After heat treatment, the alloys became almost single phase, consisting mainly of stable monoclinic phases: Al45Cr7 or Al45V7. The catalytic performance of the phenylacetylene hydrogenation reaction was tested on as-spun and heat-treated alloys that had previously been pulverized and sieved to select a powder fraction of less than 32 µm. All the tested materials show high substrate conversion, above 80% after 1 h reaction, along with high activity rate. The homogenized powders demonstrated a slightly better properties in relation to as-spun materials. These results confirm the potential of intermetallic catalysts, including the tested alloys, in hydrogenation reactions and verify the possibility of using the metallurgical method to obtain catalytically active materials.Graphical abstract

Rapid solidified ductile Cu-Al-Mn ribbon and its elastocaloric potential

Cu-Al-Mn alloys display martensitic transformation over a wide range of temperatures. In addition to low cost, this alloy is known for its low transformation stress with reasonable latent heat favoring elastocaloric applications. However, the ductility of Cu-Al-Mn can be limited owing to ordering and intergranular fracture. Through rapid solidification by melt spinning, we show that Cu-Al-Mn ribbon can be made highly ductile (greater than 8% tensile strain in the as-spun state and 10% tensile strain after heat treatment). The ductility of the melt-spun ribbon is related to the suppression of L21 ordering that is characterized through magnetic property measurement. Heat treatment of the ribbon promotes bamboo grain formation, and the latent heat is increased to 6.4 J g−1. Under tensile conditions, we show that the ribbon exhibited about 4 °C temperature change (4.4 °C on heating and 4.2 °C on cooling from 6.3% strain).

Influence of static magnetic field on rapid solidified structure and nanocrystallization behavior of Fe–Si–B–Cu soft magnetic alloys with pre-existing α-Fe nanocrystals

The effects of static magnetic field strength on the rapid solidified structure, thermal stability, crystallization structure and soft magnetic properties of melt-spun Fe81.6Si4B13Cu1.4 alloys were investigated and the corresponding related mechanism was discussed in terms of formation of pre-existing α-Fe crystals and nanocrystallization behaviors. The rise of magnetic field strength promotes the formation of the α-Fe crystals in as-spun alloy, enhances the competitive growth between the crystals during annealing, and then refines the crystals in the annealed alloy and improves their magnetic softness. The Fe81.6Si4B13Cu1.4 alloy prepared under 200 mT contains α-Fe crystals with a high number density and average size (D) of 8.3 × 1022 m−3 and 5.9 nm, respectively, in as-spun state, and possesses fine crystals with a D of 18.2 nm and excellent soft magnetic properties with a high saturation magnetization of 1.75 T, low coercivity of 9.2 A/m and high effective permeability of 10,160 at 1 kHz after annealing at 633 K for 60 min.

Microstructure and catalytic properties of rapidly solidified Al-28.5 at% Fe and Al-28.5 at% Co alloys applied for selective hydrogenation of phenylacetylene

The Al 71.5 Fe 28.5 and Al 71.5 Co 28.5 (at.%) melt-spun alloys were examined in terms of microstructure evolution and catalytic response in the semihydrogenation reaction of phenylacetylene to styrene. In the as-spun state ribbons showed a single-phase composition. The Al 71.5 Co 28.5 alloy contained columnar grains of a metastable decagonal quasicrystal, which transformed into hexagonal Al 5 Co 2 and monoclinic Al 3 Co phases after heat treatment at 900 °C. The Al 71.5 Fe 28.5 ribbon had an ordered orthorhombic Al 5 Fe 2 phase structure in both the as-spun and annealed states. The pulverized ribbons revealed considerable catalytic activity for selective hydrogenation of phenylacetylene to styrene. The best results were achieved for the as-spun quasicrystalline Al 71.5 Co 28.5 alloy, showing a conversion rate of above 80% after 2 h reaction time. The selectivity to styrene was 60% for all catalysts. The tested powders retained their phase composition following liquid reaction therefore the proposed materials can be considered for catalytic use. • The Al5Co2 and Al5Fe2 ribbons were prepare by melt spinning methods • Decagonal quasicrystal in the Al5Co2 transforms into Al 5 Co 2 and Al 3 Co after annealing • Ordered orthorhombic Al 5 Fe 2 phase in both the as-spun and the annealed Al5Fe2 ribbons • Catalytic activity of the powdered ribbons in hydrogenation of phenylacetylene • The conversion rate exceeds 80% after 2 h reaction time for quasicrystalline Al5Co2

Synthesis and characterization of soft-magnetic (Fe0.7Co0.3)75B21Ta4 metallic glasses by annealing and cryogenic treatment

In order to meet complex service environment, it is necessary to develop soft-magnetic metallic glasses (MGs) with excellent comprehensive performance. The soft-magnetic properties of (Fe0.7Co0.3)75B21Ta4 MGs are improved by appropriate annealing and cryogenic treatment (CT). The coercivity of cryo-treated and 700 K-annealed MGs is less than that of the as-spun one. The 253 K cryo-treated (139.95 emu/g) and 800 K-annealed (141.63 emu/g) ribbons reveal larger saturation magnetization, about 92% higher than the as-spun state. Moreover, the annealing and CT are beneficial to improve the efficiency of reaching magnetic saturation, and propitious to enhance the thermal stability and pitting resistance. Although possessing thicker passive film of the as-spun ribbon, an obvious gap between the film and inner surface damages the sustainable protection of inner surface. The better pitting resistance of the annealed sample at 830 K could be rationalized by the emergence of (Fe,Co,Ta)23B6.

Crystallization and its kinetics of soft magnetic (Fe1−xNix)79B12P5Si3C1 glassy alloy ribbons

A glassy phase is formed over the whole composition range for melt-spun (Fe1−xNix)79B12P5Si3C1 with x = 0; 0.2; 0.4; 0.5; 0.6 alloy ribbons and these glassy ribbons exhibit good bending plasticity. The Ni-containing glassy alloys show glass transition, followed by a supercooled liquid (SCL) region and then multistage crystallization for the alloys with x = 0.5 and 0.6 (hereafter 0.5Ni and 0.6Ni alloys). The 0.5Ni glassy alloy exhibits the largest SCL region of 43 K and good soft magnetic properties even in as-spun state, i.e., low coercive force of 4.8 A/m, effective permeability of 7400 at 1 kHz and saturation magnetization of 0.80 T. The bending plasticity remains unchanged in the wide annealing temperature range below Tg. The crystallization proceeds in the processes of glassy (G) → bcc(α)Fe(Si) + Fe3B for the 0–0.2 Ni alloys, G → fcc(γ)(Fe,Ni) + Fe3(B,C) + Fe3Ni3(B,C) for the 0.4Ni alloy and G → G’ + γ(Fe,Ni) → γ(Fe,Ni) + Ni5P2 + Fe4P + Fe3Ni3(B,C) for the 0.5Ni and 0.6Ni alloys. Analyses of crystallization reaction in isochronal and isothermal conditions were performed via Kissinger and JMAK models and the activation energy for crystallization is much larger for the 0.5Ni glassy alloy. The appearance of the largest SCL region as well as the highest activation energy for the 0.5Ni alloy is due to the necessity of the simultaneous decomposition to the four crystalline phases. The better magnetic softness for the 0.5Ni alloy is presumably due to the development of medium-range ordered atomic configurations which enable the appearances of the largest SCL region as well as the lower internal stress state. The combination of useful properties for the 0.5Ni glassy alloy is promising for useful soft magnetic materials with mass production ability.

Microstructure and Catalytic Activity of Al13Fe4 and Al13Co4 Melt-Spun Alloys

Rapidly solidified alloys with a nominal composition of Al76.5Fe23.5 and Al75.8Co24.2 (in at%), corresponding to the Al13Fe4 and Al13Co4 phases, were produced by a melt spinning technique. The microstructure and phase composition of the as-spun and heat-treated ribbons were examined by X-ray diffraction, scanning and transmission electron microscopy. The as-spun ribbons consisted of columnar grains with an average size of 1–2 μm, which increased by a factor of 2 after applied heat treatment. The Al13Fe4 as-spun ribbon comprised of two phases: grains of the Al13Fe4 phase surrounded by solid solution of Al, transformed into a single monoclinic Al13Fe4 phase after annealing. The as-spun Al13Co4 ribbons had a multiphase structure. A decagonal quasicrystalline D-phase, the monoclinic M-Al13Co4 phase, and the Al9Co2 phase were identified in their microstructure. After the heat treatment, the mixture of the orthorhombic O-Al13Co4 phase and grains of monoclinic Y-Al13Co4 were observed. The investigations of catalytic properties were performed for the phenylacetylene hydrogenation reaction using pulverized ribbons in the initial state and after annealing. The degree of conversion was in the range of 8–27% and increased with the increasing reaction temperature. The highest selectivity to styrene was obtained for the Al13Fe4 alloy in the as-spun state.

Soft magnetic properties and corrosion resistance of the annealed (Fe0.7Co0.15Ni0.15)75B21Nb4 metallic glasses

The phase structure, magnetic properties and corrosion resistance in the as-spun and annealed (Fe0.7Co0.15Ni0.15)75B21Nb4 metallic glasses (MGs) were investigated. Annealing below glass transition temperature at 693 K causes a reduction in coercivity and ameliorates the soft magnetic properties, originating from the formation of a homogeneous glassy structure. The hysteresis loops of the as-annealed ribbons, especially the 888 K-annealed one, appear to be more rectangular in their geometry, showing that the approach to saturation becomes more expeditious. The synergy of amorphous phase and nano-size magnetic α-Fe(Co) phase in the 753 K-annealed ribbon leads the improvement of saturation magnetization. The corrosion behaviors in seawater solution have been investigated by electrochemical polarization measurement. By evaluating the corrosion potential and current density, annealing treatment induces the detrimental influence in the general corrosion resistance of MG ribbons. However, compared with as-spun amorphous state, the 693 K-annealed relaxation ribbon exhibits superior passivity with lower passive current density and higher pitting resistance as revealed by wider passive region.

Effects of Si content on structure and soft magnetic properties of Fe81.3SixB17-xCu1.7 nanocrystalline alloys with pre-existing α-Fe nanocrystals

The as-spun structure, thermal stability, crystallization structure and soft magnetic properties of Fe81.3SixB17-xCu1.7 (x = 0–8) alloys were investigated. The Fe–Si–B–Cu amorphous alloys contain α-Fe nanocrystals with a high number density (Nd) in as-spun state and show uniform nanocrystalline structure and typical soft magnetic characteristics after annealing. The rise of Si content from 0 to 4 at% increases the Nd, while the further rise to 8 at% shows an adverse effect. The increased Nd enhances competitive growth between the crystals during crystallization process, then refines structure and improves soft magnetic properties of the nanocrystalline alloys. Contrarily, the decreased Nd results in coarsened nanostructure and deteriorated magnetic softness. The alloy with Si content of 4 at% contains α-Fe crystals with a high Nd of 2.2 × 1023 m−3 in as-spun state and possesses fine α-Fe grains with an average size (D) of 14 nm, low coercivity (Hc) of 7.1 A/m, high effective permeability (at 1 kHz) of 16,500 and saturation magnetic flux density of 1.77 T after annealing at 668 K for 60 min. In addition, the Hc of present Fe–Si–B–Cu nanocrystalline alloys is almost proportional to D3 due to the high ratio of uniaxial anisotropy to average random anisotropy.

Novel phase decomposition, good soft-magnetic and mechanical properties for high-entropy (Fe0.25Co0.25Ni0.25Cr0.125Mn0.125)100–B (x = 9–13) amorphous alloys

Abstract As-spun (Fe0.25Co0.25Ni0.25Cr0.125Mn0.125)100–xBx (x = 9–13 at%) alloys are fully amorphous with bending plasticity and good soft-magnetic properties. Manganese addition favors amorphous phase formation at lower B content than in comparable alloys. On heating, the alloys transform: [am] → [am’ + bcc + fcc] → [fcc] at 9–11% B; and [am] → [am’ + bcc + fcc] → [bcc + fcc + borides] → [fcc + borides] at 12–13% B. Novel observations are the formation of metastable bcc + fcc phases, and an endotherm due to the [bcc + fcc] → [fcc] transition. The Vickers hardness of 9–11% B alloys is ∼650 in the as-spun state, shows a maximum of 1010 for [bcc + fcc] state and then decreases to 750 upon transition to [fcc]. As-cast 9–11% B 2-mm-diameter rods, mainly [bcc + fcc], exhibit compressive strength of 1520–1705 MPa and plastic strain >25%. These high-strength alloys, and the as-spun amorphous alloys with soft-magnetic properties, are encouraging for the further development of structural and functional materials.

Fabrication, characterization and drug release behaviors of chitosan microfibers loaded with herbal or non-herbal drugs

Two chitosan, CS, microfibers loaded with the herbal persimmon leaves, PL, and the non-herbal metformin hydrochloride, MH, were wet spun, respectively. SEM images shown that these two CS microfibers have different surface morphologies at the as-spun state due to the PL-loaded fiber presented the squamae-like structure and the MH-loaded fiber presented some bright dots. This suggested that the PL and MH were loaded in the CS chains by different mechanisms and some loaded MH molecules out of the CS chains might be free and separated by spinning-induced extrusion forces. FTIR spectra analysis indicated that the PL was loaded in the CS chains mainly by the O-H groups and formed the interpenetration network and the MH was loaded in the CS chains mainly by the N-H groups and formed the sheathing structure. The loading of these herbal and non-herbal drugs in CS chains both shown good miscibility while the mechanical properties were reduced as compared with the pure CS fiber. The release of the PL and MH from CS fibers both followed the same Langmuir kinetics model, while the comparisons found that the released amount was greater for the PL and the release rate was faster for the MH.

Phase decomposition and mechanical properties of pseudo-high entropy Zr65(Al,Fe,Co,Ni,M)35 (M=Cu, Ag or Pd) glassy alloys

The extremely stable phenomenon to crystallization was recognized for multicomponent Zr65(Al,Fe,Co,Ni,M)35 (M = Ag or Pd) glassy alloys which are defined as a pseudo-high entropy (PHE) type with the features of positive or nearly zero heat of mixing and large atomic size mismatches among solute elements. The PHE glassy alloys exhibit two exothermic peaks (Tp1 and Tp2) on the DSC curve where their peak temperatures are 719 and 944 K for M = Ag and 727 and 929 K for M = Pd, respectively, showing a large temperature interval between Tp1 and Tp2. Even after the long-time annealing for 3.6–14.4 ks at 750 K above Tp1, no appreciable change was recognized in the X-ray diffraction patterns as well as the TEM and HRTEM images. The further increase in annealing temperature for 3.6 ks to 850 K near Tp2 causes the homogeneous precipitation of a metastable big cubic Zr2(Al,TM,M) (TM = Fe, Co, Ni) with a size of 3–5 nm. Upon heating to the temperature above Tp2, the glass + Zr2(Al,TM,Pd) phases change to Al16TM11Zr7 + ZrAl2 + PdZr. The hardness is about 485 in as-spun state, increases at the temperatures above Tp1, shows a maximum (632) in the glass + metastable Zr2(Al,TM,Pd) phases just below Tp2 and then decreases to 568 in Al16TM11Zr7 + ZrAl2 + PdZr phases. The high resistance to crystallization is due to the sluggish growth of crystalline nuclei resulting from the low atomic diffusivity and the necessity of long-range atomic rearrangements which are features for PHE glassy alloys. The Cu-containing glassy alloy does not belong to the PHE alloy and crystallizes easily to Zr6(TM,Cu)Al2 phase during the first exothermic reaction. The selection of PHE alloy composition is essential for the formation of the clustered glassy phase.

Novel method for construction of high performance nanocrystalline FeCuNbSiB toroidal core

In the current study magnetic, magneto-optical and microstructural properties of the amorphous Fe83Cu1Nb3Si5B8 alloy were properly investigated depending on the external treatments such as annealing and stress annealing. Kinetic nanocrystallization temperatures of certain ribbon were determined at the range of 500–510 °C. The amorphous ribbons produced in the as-spun state were subjected to tensile stress loading with and without rapid heat treatment of 510 °C during 5 s. Behaviors of certain ribbons were extensively investigated in terms of several factors such as magnetic properties, microstructural evaluation, magneto-optical effects and structural deformation by means of quasi-static hysteresis loops, XRD analyses, TEM micrographs, magneto-optical Kerr imaging and nanoindentation test. Present nanocrystalline Fe83Cu1Nb3Si5B8 alloy have allowed yielding not only ultrafine grain structure of around 7.02 nm but also saturation induction of 1.85 T, coercivity of 5.8 A.m−1 and saturation magnetostriction of 6 ppm. Additionally, based upon determined optimum stress annealing circumstances, toroidal nanocrystalline core was produced using a proposed stress induced winding (SIW) system. SIW system based principally on the gradient of the rotational speed of each mandrel in the standard toroidal core winding machine. Structural deformation of the core was determined by an analysis method performed on the ribbon. Accordingly, induced elastic modulus (E), Poisson's ratio (V) and residual strain (ε) in the ribbon under the influence of stress annealing by 200 MPa at 510 °C were found as 7.9 GPa, 0.39 and 0.031, respectively.

Effect of Sb substitution on crystal structure, texture and hard magnetic properties of melt-spun MnBi alloys

Melt-spun Mn50Bi50-xSbx alloys with x ≤ 5 were prepared at different solidification rates and characterized both in the as-spun state and after annealing. In the as-spun alloys, the Sb substitution leads to the formation of a metastable phase, similar to the binary “quenched high-temperature phase” but without the superstructure of the latter and exhibiting a different – increasing – temperature dependence of coercivity. The new nanocrystalline metastable phase is not only itself characterized by a high room-temperature coercivity (in excess of 20 kOe), but upon annealing it transforms into a high-coercivity (up to 13.5 kOe) “low-temperature” α phase. However, the advantage of obtaining a high coercivity without the otherwise required milling made possible by the Sb substitution is undermined by the absence of a local crystallographic texture in the melt-spun alloys. The best combination of the isotropic hard magnetic properties realized for the Mn55Bi43.5Sb1.5 composition is a remanence of 35.5 emu/g and a coercivity of 8.1 kOe. The annealed Sb-free Mn50Bi50 alloys did possess a local crystallographic alignment and, for high solidification rates, a moderate coercivity up to 5.6 kOe; however, they had an inadequate “rectangularity” in the demagnetization curve. The orthorhombic compound known as MnBi0.9Sb0.1 and described earlier as antiferromagnetic was obtained in the annealed ribbons with x ≈ 5. The compound was found to order ferromagnetically between 200 K and ≈250 K and to exhibit a significant coercivity, 14.3 kOe at 50 K. It is suggested that the MnBi0.9Sb0.1 may actually be a Sb-stabilized “new phase” observed earlier as metastable in the Bi–MnBi eutectic alloys.

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).

Nanocrystallization, good soft magnetic properties and ultrahigh mechanical strength for Fe82-85B13-16Si1Cu1 amorphous alloys

New Fe82-85B13-16Si1Cu1 amorphous alloys with low B content and high B/Si content ratios were synthesized by melt spinning for developing good soft magnetic and high strength materials. The crystallization occurs through two stages and the first-stage onset temperature increases from 673 K to 705 K with increasing B content, while the second-stage temperature remains nearly constant. The first and second stages are due to the precipitation of the α-Fe(Si) phase with a size of about 30 nm and the decomposition of the remaining amorphous phase to α-Fe(Si)+Fe3B+Fe2B, respectively. The Fe-based alloys exhibited good soft magnetic properties both in annealed amorphous and nanocrystallized amorphous+α-Fe(Si) phases. The saturated magnetic flux density, coercivity and permeability at 1 kHz are 1.7 T, 4.92 A/m and 7100, respectively, for the annealed amorphous 14B alloy and 1.74 T, 5.62 A/m and 10100, respectively, for the nanocrystallized 13B alloy. The Vickers hardness (Hv) is 803–867 for the as-spun state and it increases with decreasing B content. The Hv increases significantly by crystallization to α-Fe+amorphous phases and reaches 997–1550 for the alloys annealed at 693–763 K just before Tx2. The ultrahigh Hv is presumably due to the combination of fine nanoscale mixed phases, high volume fraction of α-Fe(Si) without internal defects and the enrichment of B into the remaining amorphous phase. Such ultrahigh Hv has not been obtained for Fe-based amorphous and crystallized alloys before and the addition of 1%Cu is essential for the ultrahigh Hv and the amorphous phase formation for the Fe-rich 85%Fe alloy. The new Fe-based alloys are encouraging as future soft magnetic and ultrahigh strength materials with low material cost.

Effect of Sm on thermal and mechanical properties of Cu-Zr-Al bulk metallic glasses

The effect of rare-earth (Sm) microalloying on the thermal stability and phase selection along with the effect of nanocrystallization on the mechanical properties of amorphous melt-spun ribbons of Zr50Cu40Al10, Zr49Cu39.2Al9.8Sm2 and Zr48Cu38.4Al9.6Sm4 alloys were investigated using differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), Vickers and nanoindentation hardness tests and micropillar compression analysis. XRD and TEM analyses showed that all samples were fully amorphous in as-spun state; however, crystallization sequences for the Sm-free and the Sm micro-alloyed samples were different during devitrification. Combined study of XRD, DSC and TEM on melt-spun ribbons show that Zr48Cu38.4Al9.6Sm4 have nanocrystallization of Cu2Sm phase with an average diameter of 10 nm, which was absent in Zr50Cu40Al10, prior to crystallization of Cu10Zr7 phase. The nanoindentation and micropillar compression tests revealed Cu2Sm nanocrystals embedded in Zr48Cu38.4Al9.6Sm4 alloy improves strength and hardness. On the other hand, presence of these nanocrystals deteriorate shear band stability and thus result in a catastrophic brittle fracture through a single shear band burst.

Effect of microalloying on crystallization behavior, magnetic properties and bending ductility of high Fe content FeSiBCuPC alloys

Effect of microalloying on microstructure, magnetic properties and bending ductility of the Fe85.7-85.8Si0.5B9-9.3P3.5-4Cu0.5-0.8C0.2-0.3 alloy ribbons with high Fe content was systematically investigated. It is found that the substitution of 0.1 at. % Cu or 0.2 at. % Cu for (B+P) content inhibits the crystallization and improves the amorphous forming ability of melt-spun Fe85.7-85.8Si0.5B9-9.3P3.5-3.9Cu0.6-0.7C0.2-0.3 alloys. The first crystallization temperature (Tx1) increases slightly with the addition of C or P content, while the second crystallization temperature (Tx2) exhibits a slightly decrease. All amorphous alloys exhibit a large temperature interval between Tx1 and Tx2, which contributes to the thermal stability and leads to the formation of a single α-Fe phase. In the as-spun state, the amorphous alloys have good bending ductility even at high Fe content. After the optimum heat treatments, the Fe85.7-85.8Si0.5B9-9.3P3.5-3.9Cu0.6-0.7C0.2-0.3 nanocrystalline alloys exhibits the excellent soft magnetic properties, such as the highest Ms of 206.4–210.2 emu/g (Bs ≈ 1.95–1.98 T) and the lowest Hc of 6.5–8.4 A/m.

Fe content dependence of magnetic properties and bending ductility of FeSiBPC amorphous alloy ribbons

Effects of Fe content on magnetic properties and bending ductility of FeSiBPC amorphous alloy ribbons before and after annealing were systematically investigated. It was found that all alloys had high amorphous forming ability and good soft magnetic properties after annealing. The transition temperature of bending ductility-brittleness decreases much faster than that of soft magnetic properties with the increase of Fe content. It is interesting that alloys with Fe content higher than 80 at.% exhibit good ductility before and after annealing at the optimal condition. The alloy with Fe content of 71 at.% is brittle even at as-spun state. The saturation flux density (Bs) and coercivity (Hc) decrease with decrease of the Fe content and deviate from a linear fitting tendency. The temperature asynchronism between magnetic properties and bending ductility of amorphous alloy ribbons was discussed. This work will bring a new perspective to study the annealing induced brittleness and a guidance for the future development of the amorphous alloys.