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In this study, structural, morphological, thermal and magnetic properties of amorphous-nanocrystalline Fe 70 Cr 10 Nb 10 B 10 (at.%) alloy are discussed. The formation and evaluation of amorphous-nanocrystalline structures of the alloy were followed by XRD, SEM-EDX, TEM, DTA, and VSM techniques. After 50 h of milling Cr, Nb, and B were completely dissolved into the Fe lattice forming 82% of the amorphous phase of the alloy. A gradual dissolution of the alloying elements also increased the lattice parameters concurrently. The lattice parameters reached a maximum value of 2.908 Å after 20 h of milling and then leveled off to a value of 2.891 Å at the end of 50 h of milling. Based on the XRD data, crystallite size and lattice strain of the alloy were calculated as 3.2 nm and 3.34% respectively. TEM analyses revealed that the alloy particulates comprised needle-shaped nanoparticles of an average size of 21 nm. The room temperature magnetic hysteresis loops showed that the increased duration of milling decreased the saturation magnetization from 91 to 24 emu/g. This was mainly due to the upsurge on the amorphous phase content in the alloy as the milling progressed. The increase in amorphous phase content and the subsequent reduction of the saturation magnetization were due to the inter-diffusion of the non-ferromagnetic Cr and B atoms into the Fe lattice. Thermal studies revealed that around 350 °C the amorphous phase of the alloy began crystallizing. The magnetic saturation of the heat-treated alloy also increased with the growth in the crystalline phases. The 50 h milled sample annealed at 700 °C was found to have the highest magnetic anisotropy as observed from the temperature-dependent zero-field cooled and field cooled magnetization measurements. The high-pressure X-ray diffraction measurements revealed that the amorphous state of the alloy remained stable up to 11.3 MPa. It also revealed the structural similarities of the Fe 70 Cr 10 Nb 10 B 10 alloy with those of the Fe 70 M 10 B 20 (M = Nb and Cr) types. For all practical purposes, the microstructural stability under high compressive pressure represents the consolidation properties of the nanostructured magnetic materials since both pressure and temperature-induced phase transformations are the primary controlling factors for the specific magnetization properties of the alloy.

In this study, four different equimolar compositions of FeCoNi, FeCoNiNb, FeCoNiCr, and FeCoNiNbCr were synthesized by the mechanical alloying method. The effects of Cr and Nb addition on the structural, morphological, and magnetic properties of FeCoNi alloy were investigated in detail. The structural aspects of the samples were analyzed by X-ray diffractometer and scanning electron microscope equipped with an energy dispersive X-ray spectrometer. High and low-temperature magnetic properties were evaluated by a vibrating sample magnetometer. It was noticed that the addition of Nb caused amorphization, while Cr promoted crystallization in the alloys. The crystallite sizes were calculated as 9.7, 3.1, 8.3, and 4.4 nm for the FeCoNi, FeCoNiNb, FeCoNiCr, and FeCoNiCrNb alloys, respectively, after 20 h of milling. The SEM images of the as-milled alloys revealed irregular and layered structures for FeCoNi and FeCoNiCr alloys of mean particle sizes around 140 and 120 µm. In contrast, the addition of Nb in these alloys, viz. FeCoNiNb and FeCoNiNbCr alloys, formed mostly spherical with irregular morphologies of particle sizes ranging between 55 and 80 µm. It was noticed that the low solubility of Cr caused precipitation at the grain boundaries of the alloy particles, and it contributed to the formation of hard structures of irregular and layered morphologies. The observed increase in the lattice parameters and lattice strain in the solid solution phases of all-alloy systems studied was mainly due to the lattice distortion and intense plastic deformations. The maximum saturation magnetization obtained from the room temperature hysteresis loops was 150.4 emu/g for the FeCoNi alloy after 10 h of milling. The additions of non-magnetic Cr, Nb, and both into FeCoNi, caused a significant decrease in the saturation magnetization. The coercivity of the as-milled alloys was also found to decrease with the reduction in the nano-crystallite sizes, which elucidated that the crystallite sizes of the alloys were smaller than the magnetic exchange length. The high-temperature magnetization curves revealed that all alloys studied had Curie temperature higher than 700 K.

The development of soft magnetic materials is fundamentally important for improving operational efficiencies of the ever-growing field of power electronics, electrical motors, and generators. It requires to meet the challenges of constantly changing fields of modern areas of applications starting from spaceships to day-to-day electronics. Many new materials with soft magnetic properties, viz. ferrous alloys, soft ferrites, amorphous and nanocrystalline magnetic alloys, have been continuously evolving since the inception of electromagnetic induction. The main drive for the continuous improvements of soft magnetic materials is primarily to enhance energy efficiency, to reduce size and weight, and to boost the power of high-frequency power electronics and electrical machines of high rotational speed. Despite some predicaments, the amorphous and nanocrystalline soft magnetic materials have become a field of major research interest since their invention four decades ago. It has been observed that the amorphous and nanocrystalline alloys exhibit better magnetic properties than the conventional soft magnetic alloys. This group of materials is produced adapting various production techniques. In this review, amorphous, nanocrystalline, and high entropy alloys (HEA) are discussed as soft magnetic materials and their electromagnetic properties are assessed. However, this review will particularly focus on the mechanically alloyed amorphous, nanocrystalline, and HEA soft magnetic materials. The soft magnetic alloys of interest for this review are grouped on the basis of Fe, Co, Ni, and FeCoNi. Furthermore, the effect of MA parameters and subsequent annealing processes on the magnetic properties is also assessed. This review brings forth a great promise in the field of soft-core magnets for high-end applications.

This study investigates the effect of adding boron as a ternary addition to binary FeCo alloys. Fe–Co–B ternary alloys with varying boron concentrations between 0 and 2 wt% were synthesized through mechanical alloying. The study aims to analyze the structural, morphological, and magnetic properties of the Fe–Co alloy matrix with the inclusion of boron. The XRD results showed a single solid solution phase of Fe–bcc structure for all alloys, regardless of the boron concentration. It was seen that the low solubility of boron in Fe–Co caused the formation of hard structures at the grain boundaries, resulting in an increase in hardness with an increase in boron concentration. On the other hand, a decreasing trend was observed in coercivity, which is ascribed to the formation of FeB at the grain boundaries, as proved from XRD analysis. An increase in boron concentration did not seem to significantly affect the saturation magnetization, which remained in the range of 190 ± 10 emu/g for all Fe–Co–B alloys. The experimental data was cross checked and further insights were gained; DFT calculations were performed using Vienna Ab Initio Simulation Package.

In this study structural, morphological, thermal and magnetic properties of equiatomic CoNiMnGaSi (base), CoNiMnGaSiCu, CoNiMnGaSiSn and CoNiMnGaSiSb alloys are discussed. The formation of solid-solution nanocrystalline bcc structure of the alloys was determined by XRD and DTA techniques. SEM–EDS analyses also revealed the homogeneous distribution of the elements. The room temperature magnetic hysteresis loops showed that as-casted alloys reached saturation easily with coercivity less than or equal to 35 Oe. As the Cu and Sn were added to the alloy, the saturation magnetization was decreased from 112 emu/g to 50 emu/g, which was mainly due to the substitution of non-magnetic atoms to the magnetic Co in the base CoNiMnGaSi alloy, whereas the addition of Sb to the base alloy did not have a significant effect on the M s . The CoNiMnGaSiSb was found to have the highest Curie Temperature of 670 K, which makes the alloy a promising candidate for power industry-related applications.

This study focuses on synthesizing and characterizing mechanically alloyed refractory high entropy alloys (RHEA) containing TiMoNb, Cr, W, and Cr + W. Analytical techniques including XRD, SEM, EDX, DTA, and TGA were employed to explore the influence of Cr and W on the alloys' structure, morphology, and thermal stability towards oxidation. XRD analysis confirmed the formation of a single-phase bcc solid solution in TiMoNbCr, TiMoNbW, and TiMoNbCrW alloys. Crystallite size decreased as milling progressed, yielding average sizes of approximately 7.2 nm, 7.4 nm, and 9.7 nm, with lattice strains of 1.143%, 1.148%, and 1.15%, respectively. Both experimental and calculated values of lattice parameters converged to around 3.1685  ± 0.002 and 3.1791  ± 0.010 Å for all three alloys. The synergy of Cr and W in TiMoNb was observed for the first time, impacting dislocation density, hardness, and oxidation stability. TiMoNbCrW exhibited reduced dislocation density and the highest hardness (502 HV). TGA indicated enhanced oxidation resistance up to 400 °C for TiMoNbCrW compared to the most vulnerable TiMoNbCr alloy.

To improve mechanical properties of S2355JR carbon steel, pre-synthesized ZrB2 nanocrystals were used to coat the metal surface by laser cladding using 2000 W CO2 laser. ZrB2 nanocrystals were synthesized by mechanochemical process. The effect of laser power on the coating layers was examined for optimizing the most effective coating conditions. Microstructural studies were carried out using optical microscope, scanning electron microscope and X-ray diffraction to analyze phase structures of the coated layers. Mechanical characteristics of the laser coated layers were evaluated by studying microhardness, wear and scratch resistance properties. Maximum hardness of the coated layers was observed while cladding with 75 and 125 W laser powers, when other processing parameters and conditions were kept at optimum levels. EDS analysis of these laser cladded layers indicated the formation of complex boro-nitrides, nitrides and carbides of Zr and Fe that contributed to vast increase in hardness of the laser-clad coating on S2355JR steel. Depending upon the laser powers used, the thickness of the coated layers was found to be in the range of 15–37 µm. The wear and micro-scratch tests results revealed significant improvement in wear properties.

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