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High entropy alloy (HEA) with shape memory effect (SME) has been the subject of great interest for the past few decades. However, with the increased demands for new materials for high thermal applications, the research activities on the multi elemental high entropy shape memory alloys (HESMA) have been increased by many folds recently. The nano crystalline HEA powder with shape memory effect developed in this study, HfZrTiFeMnSi, was produced by mechanical alloying (MA) for the first time. In this method equiatomic ratio of Hf, Zr, Ti, Fe, Mn, and Si were mixed together and milled by MA process for 100 h. The powder formed was of amorphous in nature. Elemental mapping of the powder from SEM-EDS revealed homogeneity of the alloying elements confirming successful fabrication of HfZrTiFeMnSi HEA powder. The DSC studies from ambient to 500 °C of the annealed alloy powders showed reversible austenitic to martensitic (A↔M) transformations. The A↔M transformation hysteresis seemed to vary with the milling time and annealing temperature. The enthalpy values, ΔH, for the transformation were calculated from the DSC plots using tangent method for peak area calculation. Regardless of the annealing temperature, the thermal analysis revealed that the ΔH, equilibrium temperature (T0), and crystallization temperature values decreased with the increasing milling time.

This paper delineates a single-step production method of nanostructured diiron boride (Fe2B) and its structural, magnetic and magnetothermal properties. Structurally Fe2B resembles the tetragonal copper aluminide, CuAl2. The samples of nanostructured Fe2B were synthesized by milling Fe and B powders without any pre-treatment. Single phase Fe2B nanoparticles were successfully produced with the crystallite sizes of 68 and 46 nm after milling the powders for 10 h and 20 h, respectively. The saturation magnetization of the samples was found to decrease with increased milling time indicating that the surface spin disorder plays a crucial role in the magnetic properties. The highest saturation magnetization (Ms) of 141 emu/g with low coercivity (Hc) of 48 Oe was obtained for the 10 h milled sample of Fe2B, whereas the 20 h milled sample exhibited Ms and Hc as 129 emu/g and 149 Oe. This paper also presents a detailed information on the total and atom projected densities of state functions as well as the magnetic moment contribution of the individual atoms of Fe and B in Fe2B explaining the strong room temperature ferromagnetic properties contributed by the large number of unpaired 3 d electrons in Fe. The magnetothermal properties of the as-made Fe2B nanocrystals of high magnetic moment were investigated by measuring the rise in temperature as a function of time in the presence of AC magnetic fields. The magnetic Fe2B nanocrystals show significant thermal response with the high specific absorption rate of 172 W/g, demonstrating the advantages of using Fe2B nanocrystals for the application in magnetic fluid therapy for hyperthermia.

This study aims to synthesize very pure form of LaB6 nanocrystals at low temperatures. The synthetic route employed involved low temperature magnesiothermic reduction process of La2O3 with a mixture of Mg, I2 and B2O3 at 90 °C. The powder mixtures were mechanically induced under Ar atmosphere for 3 h and then heat treated. The pure form of nano LaB6 powder produced by this technique is by far the most versatile route for the synthesis of nano-LaB6. From the XRD evidences of the synthesized powders, a correct reaction path for the reduction process has been elucidated. The average particle size of nano powder synthesized was estimated from SEM as well as XRD as 78 ± 12 nm and 61.3 ± 2.0 nm respectively, and the values were found to be in good agreement. The particle size determined by XRD was upon applying the Rietveld refinement method and using isotropic Lorentzian Scherrer particle broadening parameter (LX) of refined peak profiles. From the average size of the particulates and from the specific surface area of LaB6 (1.3 m2/g) as determined by BET method, the number of unit crystals that might have constituted a nano-particulate of size 61.3 ± 2.0 nm was estimated as 105 numbers from the crystallographic information of LaB6.

The soft ferromagnetic materials are of great industrial importance for their applications in magnetic cores for transformers, electric motors, inductors, and generators. In recent years, the trend has been to use magnetic high entropy alloys (HEAs) owing to their superior magnetic properties compared to the conventional magnetic materials. In this study, the traditional magnetic materials, (NiFeCo)95Mo5 and (NiFeCo)90Mo10 produced by conventional mechanical alloying method, were compared with the NiFeCoMo high entropy alloy produced by the sequential mechanical alloying method. Unlike conventional mechanical alloying, NiFeCoMo HEA was produced by mechanical alloying using sequential additions of Co and Mo to the preformed Fe-Ni alloy. Besides its magnetic properties, the effect of Co and Mo on the overall characteristics of the alloy was also investigated. In 60 h milled samples of the (NiFeCo)95Mo5 and (NiFeCo)90Mo10 alloys, the crystallite sizes were estimated as 10.5 and 10.8 nm respectively, whereas the crystallite size for the NiFeCoMo HEA was 15 nm. The presence of Mo in the alloy induced the formation of lamellar or layered structures of the particles. During the sequential milling to form NiFeCoMo HEA, it was noticed that the addition of Co into the preformed Fe-Ni alloy increased the magnetic saturation value due to the formation of FeCoNi alloy phase. However, further addition of Mo into the FeCoNi alloy phase reduced the magnetic saturation value of NiFeCoMo alloy significantly. After 60 h of milling the magnetic saturation value was dropped from 102.48 emu/g for the NiFeCo alloy to 60.52 emu/g for the NiFeCoMo alloy.

Nanostructured (FeCoNi)70Ti10B20 (at%) alloy was synthesized by mechanical alloying from elemental powder mixture of Fe, Co, Ni, Ti and B using ball milling. The effect of ball milling time on the evolution of structure and morphology was investigated by X-ray diffraction, scanning and transmission electron microscopy and differential thermal analysis. It was observed that the formation of solid solution of (FeCoNi)70Ti10B20 started from the very onset of the milling process. Crystallite size and lattice strains seemed to be leveled off after 20 h of milling with no further major changes. The milling process for longer periods introduced severe plastic deformations causing formation of amorphous phase of (FeCoNi)70Ti10B20. The amorphous alloy composition was confirmed by energy dispersive X-ray spectroscopy analysis that showed an excellent homogeneity of the alloying elements. The phase stability of the mechanically alloyed amorphous sample was further verified by employing high-temperature and high-pressure studies. The alloy samples heat-treated at 700 °C revealed crystallization of the amorphous phase. However, synchrotron-based high-pressure ambient temperature X-ray diffraction studies confirmed that the amorphous phase of the alloy remained stable up to the pressure of 30 GPa. The 50 h milled sample after being annealed at 350 °C showed improvement in the soft magnetic properties of the alloy, which was due to the probable elimination of the residual stress in the amorphous phase of the alloy powders.

In this paper a few hot pressed as well as sintered boron carbide (BC) systems are reviewed that showed super-high strength, which are able to withstand pressures well above Hugoniot Elastic Limit. Regardless how small it might be, BCs are known to have carbon impurities. Probably the presence of a small amount of suitable third element that can combine with the free carbon and simultaneously influence the crystal structure through migration across the grain boundary is the key to improve strength. This paper also delineates the selectivity of the third element to be able to migrate and substitute in the BC crystals.

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 A mu m. The wear and micro-scratch tests results revealed significant improvement in wear properties.

In this study, iron sulfate heptahydrate (FeSO 4. 7H 2 O) and sodium borohydride (NaBH 4 ) were used to synthesize Fe-Fe 2 B nanocrystals via the solvothermal route. Synthesis of Fe-Fe 2 B nanocrystals was carried out under Argon (Ar) gas atmosphere with aqueous solutions of FeSO 4 .7H 2 O and NaBH 4 at various concentrations and reaction time. The phases and microstructures of nanocrystals thus formed were characterized by X-Ray diffraction (XRD) spectroscopy and scanning electron microscopy (SEM). Surface areas of nanocrystals were measured by a surface area and pore-size analyzer using nitrogen adsorption-desorption method together with Brunauer-Emmett-Teller (BET) equation. The vacuum dried nanoparticles were calcined under both Ar and air at 500 oC. Nano-cylindrical structures Fe-Fe 2 B were observed while calcinating under Ar atmosphere; whereas more irregular shaped particles were obtained by calcination under air. The surface areas of nanocylinders were determined as 12 m 2 /g, 5.5 m 2 /g and 16.5 m 2 /g, for vacuum dried, Ar-calcined and O 2 -calcined products respectively. The catalytic effect of those nanocrystals for hydrogen generation were studied by determining reaction rates in aqueous alkaline solutions of NaBH 4 . Their catalytic activities were investigated by varying the amount of catalysts, and the concentrations of NaBH 4 and NaOH. The effect of temperature on the catalytic activity was also studied by varying the temperatures from 25-70 °C. It was noticed that the catalytic activity of vacuum dried nanocrystals was the highest, and it decreased with the increase in NaOH concentration. With 0.01 g of Fe-Fe 2 B catalyst in 1 % w/w NaBH 4 concentration at 25 °C, the hydrogen production rate was 570 mL of H 2 .g -1 .m -1 , which reached to 1230 at 50 °C and 2700 mL at 70 °C.

This paper relates to the study of several combinations of pre-alloyed forms of aluminium such as Al-Cu, Al-Mg, Al-Si, Si-Mg, Cu-Si, and Cu-Mg in combination with aluminium powders of a known percentage of oxide content.

Uniform hydrogenated oligo(isopcene)carboKylic acid N-alkanolamides were prepared in high yields by living anionic oligomerizalion of isoprene, followed by carboxylaliou with dry ice, hydrogcnaiion, then amidauon with several commercial alkanolamincs.

Surfactants from either polyisobutylene or alkylsuccinic anhydrides derivatized with diethanolamine in a 1:1 molar ratio with hydrocarbon and polyisobutylene chains of similar length formed lamellar liquid crystals in situ and also with added water. The repeat distance between layers was determined using low angle X-ray diffraction (LAXD), and the water penetration into the hydrocarbon space in the lamellar structure was calculated. The results revealed a significantly increased repeat distance for the polyisobutylene chain surfactants compared to the alkyl analogues. The water penetration was significantly greater for a surfactant with a decyl chain compared to the one with a dodecyl chain and was intermediate for the polyisobutylene based surfactant.