https://www.andrew.cmu.edu/user/dl0p/laughlin/pdf/PMS.pdf

Amorphous and nanocrystalline materials for applications as soft magnets

Introduction Motivation Advanced Materials Rapid Solidification Processing Mechanical Alloying Outline of the Book Metallic Glasses Distinction between Crystals and Glasses Differences between Amorphous Alloys and Metallic Glasses The Concepts of Glass Formation Thermodynamics and Kinetics of Glass Formation Methods to Synthesize Metallic Glasses Bulk Metallic Glasses Potential Resources of Literature on Metallic Glasses Glass-Forming Ability of Alloys Critical Cooling Rate Reduced Glass Transition Temperature Deep Eutectics Topological Models Bulk Metallic Glasses Inoue Criteria Exceptions to the Above Criteria New Criteria Transformation Temperatures of Glasses Thermodynamic Modeling Structural and Topological Parameters Physical Properties Computational Approaches Miscellaneous Criteria Criteria for Glass Formation by Non-Solidification Methods Synthesis of Bulk Metallic Glasses Principles of Rapid Solidification Processing General Techniques to Achieve High Rates of Solidification Melt Spinning Bulk Metallic Glasses Bulk Metallic Glass Casting Methods Bulk Metallic Glass Composites Mechanical Alloying Bulk Metallic Glass Foams Crystallization Behavior Methodology Crystallization Modes in Melt-Spun Ribbons Differences in the Crystallization Behavior between Melt-Spun Ribbons and Bulk Metallic Glasses Thermal Stability of Metallic Glasses Crystallization Temperatures and Their Compositional Dependence Annealing of Bulk Metallic Glasses Effect of Environment Effect of Pressure during Annealing Physical Properties Density Thermal Expansion Diffusion Electrical Resistivity Specific Heat Viscosity Corrosion Behavior Terminology and Methodology Copper-Based Bulk Metallic Glasses Iron-Based Bulk Metallic Glasses Magnesium-Based Bulk Glassy Alloys Nickel-Based Bulk Metallic Glasses Titanium-Based Bulk Metallic Glasses Zirconium-Based Bulk Metallic Glasses Other Bulk Metallic Glassy Alloys Mechanical Behavior Deformation Behavior Deformation Maps Temperature Rise at Shear Bands Strength Ductility Fatigue Yield Behavior BMG Composites Magnetic Properties Soft Magnetic Materials Nanocrystalline Alloys Hard Magnetic Materials Applications Special Characteristics of Bulk Metallic Glasses Structural Applications Chemical Applications Magnetic Applications Miscellaneous Applications Epilogue Size and Shape Mechanical Properties Magnetic Properties Fundamental Properties Index References appear at the end of each chapter.

Bulk Metallic Glasses

The current status of research and development in Fe-based bulk metallic glasses (BMGs) is reviewed. Bulk metallic glasses are relatively new materials possessing a glassy structure and large section thickness. These materials have an exciting combination of properties such as high mechanical strength, good thermal stability, large supercooled liquid region and potential for easy forming. Ever since the first synthesis of an Fe-based BMG in an Fe–Al–Ga–P–C–B system in 1995, there has been intense activity on the synthesis and characterisation of Fe-based BMGs. These BMGs exhibit some unique characteristics which have not been obtained in conventional Fe-based crystalline alloys. This uniqueness has led to practical uses of these bulk glassy alloys as soft magnetic and structural materials. This review presents the recent results on the glass-forming ability, structure, thermal stability, mechanical properties, corrosion behaviour, soft magnetic properties and applications of Fe-based bulk glassy a...

https://www.tandfonline.com/doi/pdf/10.1179/1743280412Y.0000000007

Iron-based bulk metallic glasses

The development of Fe73.5Si13.5B9Nb3Cu1 (FINEMET) by Yoshizawa et al. and Fe88Zr7B4Cu1 (NANOPERM) by Inoue et al. have shown that nanocrystalline microstructures can play an important role in the production of materials with outstanding soft magnetic properties. The FINEMET and NANOPERM materials rely on nanocrystalline α-Fe3Si and α-Fe, respectively, for their soft magnetic properties. The magnetic properties of a new class of nanocrystalline magnets are described herein. These alloys with a composition of (Fe,Co)–M–B–Cu (where M=Zr and Hf) are based on the α- and α′-FeCo phases, have been named HITPERM magnets, and offer large magnetic inductions to elevated temperatures. This report focuses on thermomagnetic properties, alternating current (ac) magnetic response, and unambiguous evidence of α′-FeCo as the nanocrystalline ferromagnetic phase, as supported by synchrotron x-ray diffraction. Synchrotron data have distinguished between the HITPERM alloy, with nanocrystallites having a B2 structure from the ...

Structure and magnetic properties of (Fe0.5Co0.5)88Zr7B4Cu1 nanocrystalline alloys

Fe-based bulk metallic glasses: Glass formation, fabrication, properties and applications

We have discovered the existence of metal-insulator transition at ∼220 K in the new thiospinel CuIr2S4. The electrical conductivity, σ, for sintered-powder specimens drops abruptly from 2×102S·cm-1 to 5×10-1S·cm-1 at TM−I∼220K with decreasing temperature. At temperatures T

Metal-insulator transition in thiospinel CuIr2S4

This paper reviews our recent results on some applications of new nanocrystalline soft magnetic Fe-M-B (M=Zr, Hf, Nb) alloy ribbons "NANOPERM(R)". NANOPERM(R) has a structure consisting of nanoscale bcc grains and a small amount of an intergranular amorphous layer. NANOPERM(R) exhibits high saturation magnetic flux density above 1.5 T as well as excellent soft magnetic properties. Furthermore, its remanence ratio can be controlled according to the demands of various applications. Toroidal cores with gap, common mode choke coils, ISDN (integrated service digital network) interface pulse transformers and flux gate magnetic detectors made of "NANOPERM(R) have been developed. The excellent characteristics of the components were confirmed in trial. NANOPERM(R) is therefore expected to be used widely in the magnetic application field.

Applications of nanocrystalline soft magnetic Fe-M-B (M=Zr, Nb) alloys "NANOPERM(R)"

The density and the magnetization process of the melt-spun (Fe0.75B0.15Si0.10)100−xNbx (x=1–4) glassy alloys have been investigated to clarify the origin of low coercivity (Hc). Both Hc and the difference of the densities between the crystalline and glassy phases, which corresponds to the free volume in the glassy phase, decrease with increasing Nb content. An analysis of the magnetization process based on the law of approach to ferromagnetic saturation reveals that quasidislocation dipole (QDD)-type defects are the main sources of elastic stress. The results also suggest that the pinning force for magnetic domain walls generated by one QDD-type defect is independent of the Nb content, but the number density of QDDs decreases with increasing the Nb content. Therefore, it concluded that the origin of low Hc of the glassy alloys is the low number density of QDDs which corresponds to the low number density of the domain-wall pinning sites.

Origin of low coercivity of (Fe0.75B0.15Si0.10)100−xNbx (x=1–4) glassy alloys

The magnetic properties of the glassy Fe-(Al, Ga)-(P, C, B, Si, Ge) alloys have been compared with those of the conventional Fe-based amorphous alloys to clarify the feature of the glassy alloys as a soft magnetic material. The glassy Fe-(Al, Ga)-(P, C, B, Si, Ge) alloys exhibit lower saturation magnetization (Js) than that of the conventional Fe-(B, Si, C) amorphous alloys with the same Fe content. The glassy alloys also have larger saturation magnetostriction constant (� s) than that of the conventional Fe-based amorphous alloys with the same Js. However, the

Origin of Low Coercivity of Fe-(Al, Ga)-(P, C, B, Si, Ge) Bulk Glassy Alloys

The field-cooled (FCM) and zero-field-cooled (ZFCM) magnetization of ferromagnetic fine cobalt particles in a Cu 97 Co 3 alloy has been studied. The spin-glass-like temperature dependence of the magnetization has been observed; ZFCM exhibits a spin-glass-like maximum (at T p ) and FCM is larger than ZFCM at low temperatures. However, the difference between FCM and ZFCM obviously exists far above T p . Furthermore, FCM increases monotonically with decreasing temperature even below T p while that of typical spin glasses is nearly independent of temperature. The analysis of the magnetization shows that the temperature dependence of FCM and ZFCM of Cu 97 Co 3 is well described on the basis of the superparamagnetic blocking model with no interaction between the particles, whereas that of a typical spin-glass Au 96 Fe 4 cannot be explained by the blocking model.

Teruo Bitoh

Papers

Metal-insulator transition in thiospinel CuIr2S4

Applications of nanocrystalline soft magnetic Fe-M-B (M=Zr, Nb) alloys "NANOPERM(R)"

Origin of low coercivity of (Fe0.75B0.15Si0.10)100−xNbx (x=1–4) glassy alloys

Origin of Low Coercivity of Fe-(Al, Ga)-(P, C, B, Si, Ge) Bulk Glassy Alloys

Field-Cooled and Zero-Field-Cooled Magnetization of Superparamagnetic Fine Particles in Cu97Co3 Alloy: Comparison with Spin-Glass Au96Fe4 Alloy