Fe-B Alloys Research Articles

Effect of Si and prolonged time on interfacial morphologies and cavitation erosion behavior of directionally solidified Fe-B alloy in flowing liquid zinc

The effect of Si and prolonged time on interfaces and cavitation erosion behavior of directionally solidified (DS) Fe-B alloy in flowing liquid zinc was investigated. The results show Si enriches in α-Fe intragranular and α/Fe2B boundaries to refine textured grains. DS Fe-B alloy with 2.5 wt%Si exhibits the best cavitation erosion resistance to flowing zinc, which is attributed to formation of alternating distributed Γ-Fe3Zn10 and FeSi and subsequently columnar ζ-FeZn13. Cavitation erosion resistance mechanism of DS Fe-B alloy with 2.5 wt%Si is manifested that Si-induced Γ-Fe3Zn10 and FeSi and the rooting-whisker ζ-FeZn13 layer can inhibit spallation and cracks of Fe2B and products.

Exploring Ho substituted Y-Fe-B nanocrystalline alloys and hot worked magnets

Aiming to balance the utilization of rare earth (RE) resources and develop Y-Fe-B based permanent magnets, Ho is employed as strategic substitution for enhancing the magnetic properties and thermal stability of nanocrystalline Y-Fe-B alloys. Ho substituting Y can enhance the coercivity of Y-Fe-B alloys while maintaining their excellent thermal stability. 30 at.% Ho substitution leads to an abnormal increase of remanence J r and (Y0.7Ho0.3)2Fe14B alloy exhibits good magnetic properties with remanence J r = 0.73 T, intrinsic coercivity H cj = 303 kA m−1, and maximum energy product (BH)max = 66 kJ m−3. High thermal stability with temperature coefficient of remanence α = −0.124%/K and temperature coefficient of coercivity β = −0.245%/K were obtained between 300–400 K. The results for RE-rich (Y1−xHox)2.5Fe14B alloys also show that the magnetic properties change with Ho content are similar to those of (Y1−xHox)2Fe14B alloys, but the coercivity is higher. In addition, nanocrystalline (Y0.5Ho0.5)2.5Fe14B magnets were prepared by hot-pressing and hot deformation process. Due to the lack of low melting point RE-rich phase, this alloy is difficult to be densified and deformed. The formation of high temperature RE2O3 and RE6Fe23 phases and the lack of continuously distributed RE-rich grain boundary phase are responsible for the poor texture of hot deformed magnet. The hot deformed magnet has the magnetic properties of J r = 0.50 T, H cj = 739 kA m−1, and (BH)max = 40 kJ m−3 together with high thermal stability. The micro-analysis demonstrated the chemical segregation of Y and Ho elements. Higher proportion of Ho than Y existed in main phase and grain boundary phase indicate excess Y were precipitated as Y-rich oxides.

Towards the difference in coercivity enhancement of nanocrystalline Nd-Fe-B alloys with Pr and Ho substitution

Magnetocrystalline anisotropy field (HA) is an internal factor for determining the coercivity (Hc) of the magnetic materials. Despite a theoretical HA of 73 kOe, the melt-spun Nd-Fe-B alloy achieves only 20 % of this value for Hc. Comparing Ho2Fe14B and Pr2Fe14B compounds with an identical HA of 75 kOe, we reveal that Ho-substituted Nd-Fe-B alloys exhibit a more pronounced Hc enhancement than Pr-substituted alloys. The Hc value of (Nd1-xPrx)-Fe-B alloy increased from 16.9 kOe (x = 0) to 20.7 kOe of x = 1.0 alloy, achieving 28 % of its HA value. Notably, the Ho-substituted alloys exhibited a significantly higher coercivity, reaching 28.0 kOe at x = 1.0 and establishing an impressive 38 % ratio to its HA. The coercivity of Ho-substituted alloys is controlled by both nucleation and pinning, whereas the Pr-substituted alloys follow a nucleation-type mechanism. Microstructure characterization shows Ho substitution has a positive effect on grain refinement. Furthermore, Ho tends to concentrate in the RE2Fe14B grains, leading to an increased HA of the main phase and a substantial rise in Hc.

Application of the Mixing Rule to Evaluation of the Thermophysical Properties of Amorphous Fe80B20 Alloy

Application of the Mixing Rule to Evaluation of the Thermophysical Properties of Amorphous Fe80B20 Alloy

Effect of pre-oxidation at 850 °C under low oxygen pressure on the zinc liquid corrosion resistance of Fe-20Cr-5B–3Al alloy

In the process of hot-dip galvanizing, components working in liquid zinc for a long period of time naturally corrode and fail prematurely. Meanwhile, Cr and Al elements can be used to improve the corrosion resistance of Fe-B alloy in Zn liquid, unfortunately, the α-Fe matrix still gets preferentially corroded. In this work therefore, pre-oxidation is performed under a low oxygen pressure to form oxides of Cr2O3, Al2O3 and FeCr2O4 on the surface of the alloy, which effectively prevents the diffusion of zinc liquid. The oxidation behavior of Fe-5B–20Cr-3Al alloy at 850 °C is then analyzed by thermodynamic calculation and experimentally studied. The corrosion properties of the pre-oxidized alloy in Zn-55 wt% Al liquid and pure zinc liquid are subsequently investigated. Findings revealed that the oxide film forms under oxygen pressure of 10−20.5 atm. is dense, and the thickness reaches 8 µm. Moreover, FeCr2O4 and a small amount of B and Cr oxides are distributed in the upper part of the oxide film, coupled with internal oxidation of Al2O3 on the α-Fe phase. These ensure the continuity and compactness of the oxide film, thus exhibiting the best corrosion resistance to zinc liquid and zinc aluminum liquid. Consequently, pre-oxidation of Fe-5B–20Cr-3Al alloy under low oxygen pressure at 850 °C is proposed as an efficient method to ensure corrosion resistance of the alloy in a zinc-aluminum solution.

Two-Body and Three-Body Abrasive Wear Behaviors of Fe-2wt%B Alloy Modified With Various K2SO4 Additions

Fe-B alloy is a candidate for a low-cost wear-resistant material but shows very low fracture toughness. To improve the toughness of Fe-B alloys, for this study we attempted to break the continuous network of eutectic Fe2B via K2SO4 addition and heat treatment, so that the Fe2B particles transform to be more spherical. The microstructure, mechanical properties, and two-body and three-body abrasive wear behaviors of the alloys modified with various K2SO4 additions were systemically investigated. The results show that the heat-treated alloys mainly consist of martensite and M2B (M = Cr, Mn, Fe, etc.). With the addition of K2SO4, a new phase α-MnS forms in the alloy, and the circularity value of M2B increases from 0.13 to 0.44. The impact toughness of alloy increases from 6.09 J/cm2 to 14.72 J/cm2 with an increment of 142%, although the Rockwell hardness does not show obvious change. Meanwhile, the two-body wear weight loss of alloys exhibits a “decrease and then increase” trend with increasing K2SO4 addition, while the three-body wear weight loss decreases first and then remains unchanged. The different wear behaviors were investigated and discussed.

Effect of Co, Cu, and Mo alloying metals on electrochemical and magnetic properties of Fe-B alloy

FeB-based alloys were successfully produced by the vacuum arc melting method. FeB-based alloys with various compositions were obtained by the gradual addition of different elements with Cu, Co, and Mo. The structural, magnetic, and electrochemical properties of the produced alloys were investigated. It was determined that there was a significant change in the structure with the addition of Mo. It was observed that the Fe3B phase was formed instead of Fe2B depending on the solidification rate. No changes were detected in the phase structure or microstructure, morphology of the other alloys. The hardness changed from 41.88 HRC to 64.24 HRC due to the phase change. All FeB-based alloys demonstrated soft magnetic properties. The lowest coercivity was 13 Oe for the Fe85B15 alloy, and the highest saturation magnetization was 173 emu/g for the Fe63Co21Cu1B15 alloy. While the lowest corrosion resistance was in the Fe85B15 alloy with 6.47 × 10-5 A.cm-2, the highest corrosion resistance was observed in the Fe38Co38Mo8Cu1B15 alloy with 8.21 × 10-6 A.cm-2.

Feasibility of laser-induced breakdown spectroscopy for determination of neodymium in magnet alloys

The quantification of rare earth elements in (Nd–Pr)–FeB alloys used in the production of super magnets is required to ensure the quality of the raw material and a final product with suitable properties.

Nanocrystal evolution during ultra-fast heating in an amorphous Fe85B15 alloy

During the crystallization of Fe-based metallic glasses the precipitation of the BCC-Fe nanocrystals smaller than the exchange length (30–40 nm) has been reported as an effective strategy for a reduced coercivity and an increased saturation magnetization. In binary Fe-B alloys it has been shown that nanocrystals well below the exchange length can be obtained by rapid heating above 100 K/s. In order to determine if the fast heating process can yield a further refinement in nanocrystal size, the influence of different heating rates (0.17–5000 K/s) on the crystallization behavior of an amorphous Fe85B15 alloy was investigated using Flash DSC and TEM. Above a critical heating rate (500 K/s), the number density and diameters of BCC-Fe nanocrystals become saturated due to diffusion-field impingement that enriches the amorphous matrix with B that leads to the precipitation of Fe3B nanocrystals that deteriorate the magnetic properties.

Morphology and magnetic properties of rapidly quenched Fe-B alloys

Crystallization kinetics and the effect of annealing on the microstructure, morphology and magnetic properties of rapidly quenched Fe-B alloys are studied in this paper. Fe-B ribbons with different boron content were prepared ranging from 12 to 25 at%, covering the extended glass formability limit in hypoeutectic compositions to hypereutectic limit. Fe-B alloys were prepared by planar flow casting in the form of ribbons approximately 20 µm thick and 6 mm wide. The chemical compositions are Fe75B25, Fe80B20, Fe83B17, Fe86B14 and Fe88B12. Resistivity measurements were taken place at different heating rates, illustrating the phase transformations, aiding in the calculation of Avrami and Kissinger parameters. Soft magnetic properties of the Fe-B alloys were investigated by hysteresis loop measurements before and after annealing. XRD, DSC, TGA and TEM measurements illustrated the mechanisms of the crystallization process. The crystallization of Fe100-xBx amorphous alloys containing <17 at% Boron occurs by two stages of reaction. In this work, the crystallization process and Curie temperature for Fe100-xBx (12 < x < 25) are studied. Ribbons with boron content above 12 at% were found to be fully amorphous; small amount of quenched-in nano-crystallinity was present in the as-cast alloy with 12 at% B. Each composition has been annealed to achieve 5 %, 50 % and 95 % of crystallinity. In the first stage of crystallization, α-Fe phase with bcc structure crystallizes from amorphous matrix.

Effect of Silicon Content on Microstructures and Properties of Directionally Solidified Fe-B Alloy.

In order to investigate the effect of Si content on the microstructures and properties of directionally solidified (DS) Fe-B alloy, a scanning electron microscope (SEM) with an energy dispersive spectrum (EDS), and X-ray diffraction have been employed to investigate the as-cast microstructures of DS Fe-B alloy. The results show that Si can strongly refine the columnar microstructures of the DS Fe-B alloy, and the columnar grain thickness of the oriented Fe2B is reduced with the increase of Si addition. In addition, Si is mainly distributed in the ferrite matrix, almost does not dissolve in boride, and seems to segregate in the center of the columnar ferrite to cause a strong solid solution strengthening and refinement effect on the matrix, thus raising the microhardness of the matrix and bulk hardness of the DS Fe-B alloy.

Peculiarities of conventional HDDR process in (Nd,Pr)-Fe-B alloy powders under low hydrogen pressure

The relationship between the temperature of the start, peak and finish of conventional disproportionation and recombination, in hydrogen, reactions and the low starting hydrogen pressure of 10, 20, 30, 40, 50, 60, 70 and 80 kPa and maximum processing temperature of 950–1015 °C was studied by DTA and X-ray diffraction measurements for 10 g of (Nd,Pr)-Fe-B ferromagnetic powder batches. It was shown that the starting temperature of the disproportionation reaction increases when hydrogen pressure decreases. A similar dependence took place for finishing temperature of the disproportionation when pressure was in the range of 40–80 kPa. At a hydrogen pressure of 10–30 kPa, finishing temperature of the disproportionation decreased with decreasing of pressure. The temperature of the recombination reaction in hydrogen increased with increasing of the hydrogen pressure. The non-equilibrium pressure–composition–temperature schema with four zones for the (Nd,Pr)-Fe-B alloy–hydrogen system was built. The remnants of the (Nd,Pr)2Fe14B phase and disproportionation products – (Nd,Pr)H2±x, α-Fe and Fe2B were in zone I – zone of the disproportionation reaction and in zone II – interstitial zone. The recombined (Nd,Pr)2Fe14B phase, (Nd,Pr)H0–2±x, α-Fe and Fe2B phases were in the zone III – zone of the recombination reaction. And the (Nd,Pr)2Fe14B phase, recombined in hydrogen, existed in the zone IV – zone of the existence of (Nd,Pr)2Fe14B phase.

Development of bonded (La,Ce,Y)-Fe-B permanent magnets with higher performance/cost ratio than Nd-Fe-B and (Nd,La,Ce)-Fe-B magnets

Aiming at developing cost-effective bonded permanent magnets, the microstructure, magnetic properties, thermal stability, corrosion resistance, and mechanical properties of bonded (La,Ce,Y)-Fe-B magnet were investigated and compared with Nd-Fe-B and (Nd,La,Ce)-Fe-B magnets. Only RE2Fe14B and Ce(La) grain boundary phases were found in the melt-spun (La,Ce,Y)-Fe-B alloy with a composition of [(Ce0.7La0.3)0.8Y0.2]17Fe78B6, and no paramagnetic CeFe2 phase was detected, which is beneficial to hard magnetic properties. Bonded (La,Ce,Y)-Fe-B magnet exhibits a combination of magnetic properties with intrinsic coercivity Hcj = 330 kA/m, remanence Jr = 0.40 T, and maximum energy product (BH)max = 21.7 kJ/m3, compared to Hcj = 519 kA/m, Jr = 0.52 T, and (BH)max = 43.8 kJ/m3 for (Nd,La,Ce)-Fe-B magnet and Hcj = 751 kA/m, Jr = 0.66 T, and (BH)max = 75.3 kJ/m3 for Nd-Fe-B magnet. Despite its relatively low hard magnetic properties, (La,Ce,Y)-Fe-B magnet exhibits the highest performance/cost ratio. In the temperature range of 300–400 K, (La,Ce,Y)-Fe-B magnet shows better thermal stability than Nd-containing magnets, demonstrated by the high temperature coefficient of coercivity (-0.181%/K). The corrosion processed of bonded magnets are studied, and (La,Ce,Y)-Fe-B magnet exhibits better corrosion resistance than other magnets. The mechanical properties of various bonded magnets were also investigated and the highest compressive strength was obtained in (La,Ce,Y)-Fe-B magnet, possibly due to its higher density and the less brittleness of (La,Ce,Y)-Fe-B alloy. This work is beneficial to accelerating the industrialization of high abundance RE magnets.

Chemical Characterization in the Production Chain of Permanent Magnets by Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES) – Precise Quantification of Nd, Pr, Fe and B in Super-Magnets Samples

Super-magnets, materials whose strong magnetic activity is an attractive differential for the high-tech industry, may have their magnetic performance affected by small variations in their chemical composition. For example, the neodymium and praseodymium content can change the physicochemical properties of the permanent magnets. Aiming at a strict chemical quality control, this work developed an analytical method to quantify the major elements in the materials involved in the production process of didymium (the mixture of neodymium and praseodymium) super-magnets. The simultaneous determination of Nd (401.225 nm), Pr (414.311 nm), Fe (259.837 nm) and B (249.678 nm) in three different sample types (didymium oxide, metallic didymium and (Nd,Pr)-Fe-B alloy) was performed by sample dissolution in acidic media, followed by instrumental measurements using an Inductively Coupled Plasma Optical Emission Spectrometer. Linear calibration curves were obtained with high coefficient of determination (0.9983 ≤ R2 ≤ 0.9999) and with appropriate limits for determining these elements at the percentage level, reaching detection limits less than 0.07 cg g-1. The precision of the method was improved by weighing of the solutions during all the dilution steps and was evaluated by the coefficient of variation associated to instrumental precision (0.3 – 0.7%), method intermediate precision (1.9 – 3.1%) and also by the typical mass fraction provided as uncertainty (0.04 – 0.20 cg g-1), reaching the pressing need to distinguish the content of the rare earth elements in less than 1 cg g-1. The accuracy of the method was assessed by spiked and recovery test (96-104% for spikes equal to or greater than 0.50 cg g-1) and also by the use of different analytical methods, involving the participation of other laboratories, obtaining an acceptable degree of agreement (85 – 107%).

Phase precipitation and magnetic properties of melt-spun ternary Gd2Fe14B alloy and advantages of gadolinium substitution in Y2Fe14B alloy

To take the advantage of gadolinium (Gd) in developing and manufacturing RE-permanent magnets, the magnetic properties and phase precipitation behavior of Gd2Fe14B alloys prepared by melt spinning were investigated in this work. The results show that optimally direct quenched nanocrystalline Gd2Fe14B alloy exhibits the magnetic properties with remanence Jr of 0.51 T, coercivity Hc of 187 kA/m, and maximum energy product (BH)max of 33.1 kJ/m3. It also shows excellent thermal stability with a small negative temperature coefficient of Jr (α = −0.066%/K) and a positive temperature coefficient of Hc (β = 0.171%/K). The phase precipitations of as spun Gd2Fe14B alloy during melt spinning and over-quenched amorphous Gd2Fe14B alloy during heat treatment were clarified. The magnetic properties of the crystallized alloys annealed at 800 °C are close to those of the optimized directly quenched as-spun alloys, indicating good performance stability under various processes. In addition, the role of Gd substitution in (Y1–xGdx)2Fe14B alloys was systematically studied. Gd substitution can significantly enhance the thermal stability and decrease the irreversible remanence loss of Y2Fe14B alloy. With increasing Gd content, Gd-doped Y2Fe14B alloys show continuous enhancement of Hc at elevated temperatures. The highest β value of 0.22%/K was obtained in (Y0.2Gd0.8)2Fe14B alloy at 300–400 K. Gd substitution is not only effective in improving the exchange coupling effect and corrosion resistance of Y2Fe14B alloy but also superior to Nd in terms of improving the oxidation resistance. The present work has certain instructions for designing and developing new low cost RE permanent magnets with improved thermal and environment stability.

The Microstructure and Corrosion Resistance of Fe-B-W-Mn-Al Alloy in Liquid Zinc.

The microstructure, interfacial characteristics, and corrosion resistance of Fe-W-Mn-Al-B alloys in molten zinc at 520 °C have been investigated using scanning electron microscopy (SEM), X-ray diffractometry (XRD), and electron probe micro-analysis (EPMA). The experimental results indicate that the Fe-B alloy with 11 wt.% W, 7 wt.% Mn, and 4 wt.% Al addition displays a lamellar eutectic microstructure and excellent corrosion resistance to molten zinc. The toughness of M2B-type borides in the hyper-eutectic Fe-4.2B-11W-7Mn-4Al alloy can be more than doubled, reaching 10.5 MPa·m1/2, by adding Mn and Al. The corrosion layer of the Fe-3.5B-11W-7Mn-4Al alloy immersed in molten zinc at 520 °C comprises Fe3AlZnx, δ-FeZn10, ζ-FeZn13, and η-Zn. The lamellar borides provide the mechanical protection for α-(Fe, Mn, Al), and the thermal stability of borides improves as the fracture toughness of the borides increases, which jointly contribute to the improvement of the corrosion resistance to the molten zinc.

Fe2O3@FeB composites facilitate heterogeneous Fenton process by efficient Fe(III)/Fe(II) cycle and in-situ H2O2 generation

In this study, we fabricated a micro-nano structured Fe2O3@FeB composites by treating commercial Fe2O3 with sodium borohydride. The outside amorphous FeB alloy shell endowed the Fe2O3@FeB with remarkable Fenton-like performance in organic pollutants oxidation by efficient Fe(III)/Fe(II) cycle. For instance, the pseudo first-order rate constants of RhB degradation using Fe2O3@FeB as Fenton reagent was 74.6 times that of the Fe2O3 counterpart, the hydroxyl radical generation rate of Fe2O3@FeB was 1-3 orders of magnitude larger than that of other heterogeneous Fenton reagent. Further mechanistic study unveiled that FeB was oxidized accompanying with Fe(0) and B(0) continuously donated electrons to Fe(III) to secure the efficient generation of surface Fe(II), which could generate additional H2O2 by consecutive single-electron molecular oxygen activation (O2→•O2−→H2O2), leading to enhance •OH production and Fenton-degradation toward typical pollutants. This study provides a facile route for efficient heterogeneous Fenton and strengthens the vital role of molecular oxygen activation on Fenton-like process.

Fundamental properties of melt-spun stoichiometric Y2Fe14B alloy and the advantages of Nd substitution

Here we investigate the effects of wheel speed and heat treatment on the melt-spun ternary Y2Fe14B alloy, aiming to clarify its structure, phase precipitation and magnetic properties. For directly quenched alloys, the optimum magnetic properties can be achieved when the wheel speed is within a relatively wide range of 30–40 m/s. The Y2Fe14B alloy prepared at 36 m/s shows the highest coercivity of 149 kA/m and remanence of 0.88 T with the maximum energy product (BH)max of 6.8 MGOe due to the single hard magnetic phase structure. For the amorphous ribbons prepared at 50 m/s, when the annealing temperature increases from 773 to 1073 K, the α-Fe phase precipitates first accompanied by the appearance of Y2Fe14B phase and a small quantity of Fe-B phase. The magnetic properties of annealed samples are much lower than those of the optimized as-spun alloys. The effects of Nd substitution for Y on the structure, magnetic properties and thermal stability of (Y1-xNdx)2Fe14B (x = 0–1) alloys have been systematically investigated. The Hcj and (BH)max exhibit almost linear increase with the increasing Nd substitution. Relatively low temperature coefficients can be obtained in the Nd substituted alloys. The current results are important for exploring high performance and low cost Y­based rare earth permanent magnets with improved thermal stability.

Development of cost-effective nanocrystalline multi-component (Ce,La,Y)-Fe-B permanent magnetic alloys containing no critical rare earth elements of Dy, Tb, Pr and Nd

Here we first report the fully abundant rare earth (RE)-based nanocrystalline multi-component (Ce,La,Y)-Fe-B alloys containing no critical RE elements of Nd, Pr, Dy, and Tb by melt-spinning technique. The roles of La and Y substitutions for Ce have been fully understood. La plays a positive role on both thermal stability and room-temperature (RT) magnetic properties. The enhanced coercivity Hcj by partial substitution of La is attributed to the increases of anisotropy field HA and the formation of continuously distributed grain boundaries resulting from the suppression of CeFe2 phase. Although Y substitution is not benefit for Hcj, both remanent polarization Jr and thermal stability have been effectively improved since Y2Fe14B shows relatively high saturation magnetization Ms and a positive temperature coefficient of HA over a certain temperature range. In addition, RE element segregation has been confirmed, La prefers to enter into the grain boundaries than Ce and Y prefers to remain in the 2:14:1 phase. Based on these understanding, a series of melt-spun (Ce,La,Y)-Fe-B alloys have been designed. A relatively good combination of magnetic properties with maximum energy product (BH)max=7.4 MGOe, Hcj=400 kA/m, and Jr=0.63 T has been obtained in [(Ce0.8La0.2)0.7Y0.3]17Fe78B6 alloy, together with high Curie temperature (Tc=488 K) and low temperature coefficients of remanence (α=-0.255 %/K) and coercivity (β=-0.246 %/K).

Prediction of density in amorphous and nanocrystalline soft magnetic alloys: A data mining approach

The density of amorphous and nanocrystalline soft magnetic alloys is often vital to accurately estimate the saturation magnetic polarization and other properties. However, this information is often missing from the literature of amorphous and nanocrystalline alloys, possibly due to the challenges associated with using the Archimedes buoyancy method with high specific surface area melt-spun ribbons. In this work, a review of the literature has been conducted to determine the density (ρ in 103 kg/m3) of alloys in an amorphous state and, in combination with our experimental observations, is found to be well described by the following regression function: ρ = 7.751 + 0.010CCo + 0.010CNi + 0.027CNb + 0.017CCu – 0.020CB – 0.039CSi – 0.032CP, where Ci is the content of i element in at.% and the fitting error is within approximately 1%. Unlike previous works in this area, this study estimated the change in density upon amorphization and subsequent nanocrystallization for melt-spun Fe-B alloys using a He gas pycnometer. A selection of other common soft magnetic alloy systems including FINEMET, NANOPERM, NANOMET and HiB-NANOPERM are also tested. The change in density upon nanocrystallization is seen to vary between 0.5 and 3%, depending on the alloy composition. This change in density is well described by the volume-weighted average densities of the residual amorphous and crystalline phases. The difference in density between a crystalline precursor ingot and after amorphization by melt spinning was observed to vary between 2 and 3%.