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We have produced powders of nanostructured and amorphous alloys as well as bulk amorphous alloys with composition Zr₆₄Cu₁₈Ni₁₀Al₈ by mechanical alloying and by quenching arc melted melts in water cooled cooper dies, respectively. The alloys were investigated by X-ray diffraction as well as by thermal analysis in order to determine the structure and thermal properties. The mechanical alloyed amorphous powders and bulk amorphous cylinders show the same thermal and X-ray characteristics. For the amorphous powders, we find that the glass transition temperature T_g is 657 K and the crystallization temperature T_x is 752 K. For bulk amorphous alloys with the same composition prepard by arc melting and liquid quenching T_gis 655 K and the T_x is 725 K. Moreover for the bulk amorphous alloys the supercooled liquid region Δ T_xg is 70 K, the reduced glass transition temperature t_g is 0.557, the Lu–Liu parameter γ which represents the glass forming ability for bulk metallic glasses is 0.396 and experimentally the critical cooling rate R_c takes the value 7 K s^-1.

We report on the effects of using various doping 3d, 4d and 5d transition metal elements on the stability of the supersaturated FCC Ag–Cu solid solution prepared by mechanical alloying. We find that the addition of W does not have any influence on the stability of the Ag–Cu solid solution. Moderate effects are observed for Ru, Fe and Co, while the addition of Ni partially destabilizes the Ag–Cu solid solution. The results are discussed in the framework of kinetic and thermodynamic processes.

The motivation of this research is to develop a process for producing Ti/Al composite powders that enable synthesis of a single-phase TiAl intermetallic bulk material, which is then used as a target for physical vapour deposition (PVD) coating. This study reports the effects of milling time, amount of process control agent (PCA) added as well as the powder-to-medium ratio on the microstructure of the Ti/Al composite powder. Optical microscopy and scanning electron microscopy (SEM) were used to evaluate the level of mixing and the resulting powder particle size. X-ray diffraction analysis and differential thermal analysis were used for determining the phase constituents and the solid state reaction temperature of the as-milled powders.

Mechanical alloying by high energy ball milling is a promising method for the production of bulk metallic glasses, amorphous alloys and nanostructured materials. Amorphous alloys reinforced by nanocrystals represent a big step in the optimization of new ultra high strength materials. Nano-scale W-Y solid solutions were synthesized by high energy ball milling. Only 1 at. % oxygen can stabilize the bulk metallic glassy state of Zr₅₄Cu₁₉Ni₈Al₈Si₅Ti₅O₁ to higher T_x and to large supercooled liquid range ΔT_xg.

High energy ball milling was performed on a mixture of titanium and aluminum elemental powders with a composition of Ti-48(at.%)Al. Stearic acid was added to this powder mixture as a process control agent (PCA) to study its effect on the microstructure evolution and crystallite size of the milled powder after various milling times. Phase compositions and morphology of the milled powders were evaluated using X-ray diffraction and scanning electron microscopy. Crystallite sizes of milled powders were determined by Cauchy-Gaussian approach using XRD profiles. It was shown that addition of 1wt.% of stearic acid not only minimizes the adhesion of milling product to the vial and balls, but also reduces its crystallite sizes. It has also a marked effect on the morphology of the final product.

The effects of mechanical alloying on the microstructure of binary and ternary powder mixtures with stoichiometric compositions of Mg₂Ni and Mg₂Ni_0.75Nb_0.25 were studied, respectively. Also, the electrode properties of the milled products were investigated in 6M KOH solution. X-ray diffraction and scanning electron microscopy of the milled products showed the formation of Mg₂Ni-based nanocrystallites after 15 and 10h of milling using the initial binary and ternary mixtures, respectively. It was found that partial substitution of Nb for Ni has beneficial effect on the formation kinetic of nanocrystalline Mg₂Ni. Longer milling times resulted in the formation of an amorphous phase. A relatively high discharge capacity of 350mAhg^-1 was measured for the electrode made up of the ternary milled product after 20h. Also, the ternary milled product showed longer discharge life. This ternary electrode showed a microstructure consisting of Mg₂Ni nanocrystallites and an amorphous phase. Nb substitution for Ni was found to be beneficial to electrode properties of the milled products.

NiTi intermetallic with nanocrystalline structure was produced by mechanical alloying of the elemental powders and the effect of subsequent heat treatment was investigated. The products were characterized using X-ray diffraction and microhardness measurements. The results showed that after 60 h of mechanical alloying, disordered B2-NiTi phase can be obtained as a metastable phase at room temperature with grain size of 25 nm, lattice strain and high microhardness of 1.2% and 922 HV, respectively.

After heat treatment, disordered structure transformed to ordered NiTi and a small amount of NiTi2 and Ni3Ti phases. The long range order parameters of nanocrystalline NiTi were obtained to be 0.63 and 0.94 after annealing for 30 and 60 mins respectively. After 30 mins of heat treatment, 81.5% of Ni (or Ti) atoms were on the right sites and after 60 mins it increased to 97%. Grain growth and decrease of microhardness and lattice strain were also observed after heat treatment. After 60 mins of heat treatment the grain size, lattice strain and microhardness of NiTi were 95, 0.09 and 624 HV respectively.

Amorphous/nanocrystalline 50Ni–50Ti powders were synthesized from elemental Ti and Ni powders by solid state synthesis utilizing low energy mechanical alloying with times up to 100 h. The produced powders were investigated by X-ray diffraction and differential scanning calorimetry to study phase transformations that occurred during heating in the calorimeter. It was found that at the first stage of the heating process, a disordered NiTi phase was formed at temperature of about 400°C. Further investigations indicated that this phase transformed into the Ni₃Ti and Ti₂Ni intermetallic compounds after heating at a temperature of about 800°C.

An amorphous/nanocrystalline 50Ni–50Ti powder was produced from elemental Ti and Ni powders by solid state synthesis utilizing low energy mechanical alloying with times up to 100 h. The morphology, microstructure, and phase composition of the milling products were evaluated by using scanning electron microscopy and X-ray diffraction analysis. The results indicated that there was no chemical reaction between the elements during the milling process, which led to the direct formation of an amorphous/nanocrystalline structure without any intermediate phase (intermetallic and/or solid solution phase) formation. It seems that the second kind of amorphization process proposed by Weeber and Bakker is governed. It was shown that the formation of amorphous phase was started after 80 h and developed during the milling for 100 h.

A new magnetorheological (MR) fluid was synthesized by dispersing Fe₈₄Nb₃V₄B₉ nanocrystalline powders in a nonvolatile ionic liquid (N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate), which is stable from 282K to 573K. The structure, morphology, and magnetization of Fe₈₄Nb₃V₄B₉ nanocrystalline powders prepared by mechanical alloying were analyzed by using an X-ray diffractometer (XRD), a vibrating sample magnetometer (VSM), and a scanning electron microscopy (SEM), respectively. The magnetic clusters of the synthesized MR fluid were observed by using a digital microscope, and its MR properties were measured by using a cone-plate type viscometer. The experimental results showed that Fe₈₄Nb₃V₄B₉ nanocrystalline powders with an average grain size of 10–20 nm can be prepared by mechanical alloying. The MR fluid is magnetic-field-responsive, behaves like non-Newtonian fluids, and its magnetorheological properties are influenced by the applied magnetic flux density and the width of magnetic clusters.

Nanocrystalline FeNi and Ni₃Fe alloys were prepared by mechanical alloying of Fe and Ni elemental powders using a planetary ball mill under protection atmosphere. X-ray diffraction measurements were performed to follow alloy formation process in these alloys. A heat treatment of 1 h at 800°C was carried out to relax the internal stresses of the milled samples. Morphological evolution of powder particles was revealed by scanning electron microscopy. The value of lattice parameter was reached to 0.35762 nm and the hardness was found to be 686 HV at 30 h milled FeNi powder. In the case of Ni₃Fe the values of 0.3554 nm and 720 HV were obtained for lattice parameter and hardness, respectively.

Cobalt–nickel ferrite (Co_0.5Ni_0.5Fe₂ O₄) were prepared using a high energy milling and sintering. The starting raw materials of NiO, Co₃O₄ and Fe₂O₃ were subjected to 12 hr milling using a Spex8000D mixer/mill. The resulting material was molded into samples of toroidal/disc shape and subsequently sintered at various temperatures from 600 to 1000° C, at 100° C interval. The effect of sintering temperature on microstructure, saturation magnetization (M_s), and coercivity (H_c) was reported. The frequency dependence of the magnetic and dielectric properties such as permittivity, loss tangent, permeability and loss factor were investigated in the frequency range of 10 MHz–1.8 GHz. The results show that the real part of the permittivity at individual temperatures was constant within the measured frequency, while the loss tangent values decreased gradually with increasing frequency. The real permeability on the other hand remained fairly constant over certain frequency (around 1.0 GHz), and thereafter increases towards saturation thereby showing a good potential in the microwave frequencies region.

In this paper we have tried to develop a semi-empirical formula for estimation of starting time of reactions during mechanical alloying process according to self-propagating high temperature synthesis (SHS) mechanism. For this purpose, three SHS systems containing Ti–C, Mo–Si and Si–C were selected and their behaviors were observed. Aforementioned systems were milled in a planetary ball mill equipped with temperature sensor detector of cups. Samplings were done at different times of discontinuously milling. To change mills' energy, stainless steel and tungsten carbide balls were used. In order to detect the phases and characterizations of milled powder, XRD instrument was utilized. Results showed that all productions were synthesized after sudden increase in temperature. Maximum measured temperature and critical time had up and downtrends for production of TiC, MoSi₂ and SiC, respectively. Crystalline size of milled powder had nano-meter scale. By using experimental data along with theoretical equations, a semi-empirical formula between critical time for transformation of raw materials to productions, type of milled system and ball mill parameter can be presented with high accuracy. According to calculated formula, critical time was related to ball mill energy and Gibbs free energy of milled system with direct and inverse proportionality, respectively.

Pure SnO₂ based wide band gap semiconductors were prepared by mechanical alloying method by using steel and tungsten carbide vials. They were further annealed at 900°C. The XRD patterns could be refined by using P4₂/mnm space group with typical lattice parameters a = b = 4.7322 Å and c = 3.1848 Å. The as milled powders obtained from both the vials exhibit room temperature ferromagnetism (FM) without any transition element doping. However upon annealing, the FM was destroyed in one of the samples. The observed FM is explained in terms of oxygen vacancy and defects induced electrons and exchange interaction between them. The ferromagnetic transition temperature obtained from the temperature variation of magnetization was found to be 915 K. The initial magnetization data could be analyzed in terms of bound magnetic polaron model. The resonance field shift in electron spin resonance spectrum is explained in terms of observed ferromagnetism.

The effects of carbon nanotubes (CNTs) on mechanical and tribiological properties of the NiFe/CNT composites prepared by high energy mechanical alloying and hot pressing, were investigated. Bulk samples were prepared by sintering of cold pressed (300 MPa) samples at 1040°C for 1 h. X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and optical microscopy were employed for evaluation of the phase composition, surface morphology and porosities of the samples. The microhardness of as-milled Ni₃Fe and NiFe powders reached to 720 and 650 VHN, respectively. The hardness of NiFe and Ni₃Fe bulk samples reduced to 190 and 270 Vickers because of the grain growth during sintering and remaining porosity. The hardness of NiFe-CNT and Ni₃Fe-CNT bulk samples reached to 360 and 400 Vickers, respectively. The friction and wear properties of the bulk samples were investigated under dry conditions using a pin-on-disk test rig under an applied load of 8 N. The wear rate, mass loss and friction coefficient of the composite samples remarkably reduced in comparison with NiFe and Ni₃Fe matrix alloys which demonstrate effects of the CNTs on mechanical and tribiological behavior of the composites resulting from the excellent mechanical properties and unique topological structure of the CNTs.

Fe_xCu${}_{100-x}$ binary alloys attracted much attention owing to their rich magnetic phase diagram and the challenges of achieving single phases in these systems. Despite early efforts put toward studying the physical properties of low-Cu doping in Fe–Cu alloys, a detailed understanding of the magnetic, structural and electrical properties of high Cu doping in Fe–Cu alloys remains not clear. In this report, we use X-ray diffraction (XRD), scanning electron microscopy, electrical transport and magnetic measurements to gain more insight into Fe${}_{15}$Cu${}_{85}$ single-phase alloy system. Experimental findings show that the samples exhibit a second-order phase transition, which is consistent with the classical mean-field model. Moreover, negative magnetoresistance is observed at all temperatures and explained through classical models.

Ball milling technique has been extensively used to prepare different metastable states with nanocrystalline microstructures from intermetallic compounds. The present study was made on the identification of the changes in magnetic and electronic properties as a result of high-energy ball milling of Fe-50 at.%Al alloy samples. The phase formation and physical properties of the alloys were determined as a function of milling time by means of Mössbauer and X-ray photoelectron spectroscopy (XPS). The Mössbauer results show the formation of nanostructured body-centered cubic (BCC) FeAl alloy only after 5 h of mechanical milling and the same is also confirmed by Scanning electron microscope (SEM) and Transmission electron microscopy (TEM) studies. Mössbauer studies further confirm that there is magnetic behavior retention in the FeAl alloy samples even after 5 h of milling but magnetization decreases as the milling time increases. The reason for the same is due to the shocks and fracturing of the Al atoms embedded in the sites of Fe and as a result of which Fe–Fe nearest neighbors decreases. Secondly, with the increase in milling time, the particle size and the number density of equiatomic BCC Fe₅₀Al₅₀ grains decrease while the volume of grain boundary containing a solid solution of BCC FeAl and concentration of Al in a solid solution of BCC FeAl at the grain boundary increases as a result of which magnetization decreases. The shift in the binding energy of Fe_2p and Al_2p core level towards higher binding energy also supports the alloy formation after milling.

Bi-Sr-Ca-Cu-O superconductors have been prepared from the constituent pure metals by mechanical alloying in air and succeeding sintering at high temperatures in flowing oxygen. X-ray patterns from the milled powders indicate that the dissolution of excess Cu and Bi in the Bi-Sr-Ca-Cu matrix occurs progressively with milling. However, a prolonged milling resulted in amorphous-like diffraction patterns with the first peak centered around 30°. The particle size rapidly asymptotes to a fixed value near 30 h milling. The X-ray patterns of the sintered materials are in good agreement with those of the orthorhombic structure reported in the superconducting Bi-base oxides. The low T_c phase in the Bi-base oxides was identified from the resistivity and susceptibility measurements. The superconducting temperature appears to be sensitive to the milling conditions.

Mechanical alloying (MA) has been utilized to synthesize many equilibrium and/or nonequilibrium phases. During the MA process, alloys are formed by the solid-state reaction. Solid solution has been obtained by MA, strain occurs due to the dissolution one component in the binary system. An understanding of the strain in mechanical alloyed Ti–Al, Fe–Al, Ni–Al from the electronic level has remained elusive. In this communication, atomic strain behavior of Ti–Al, Fe–Al, Ni–Al systems is analyzed on the basis of the TFDC (abbreviation of the name of Thomas, Fermi, Dirac, and Cheng) electron theory. Lattice strain of Ti, Fe, Ni, and Al are compared with available experimental results. A very good coincidence was found.

Ti-addition to hydroxyapatites [Ca₁₀(PO₄)₆(OH)₂–HA] with 5.0 wt.% Ti content, was successfully deposited on titanium substrate by mechanical alloying (MA) method. The X-ray Diffraction (XRD) data indicated that some changes take place in the HA lattice as well as in the Ti substrate. The coating thickness of the as-synthesized sample was about 91.1 μm. Ti incorporation into the apatite structure caused lattice shrinkage. The heat treated sample shows that dominant phase was HA up to 600°C. The Ti-doped HA steadily transformed to β- and α-tricalcium phosphate at 800°C. Scanning Electron Microscopy (SEM) observations revealed cracks above the temperature of 600°C. The presence of cracks could be due to the difference in coefficients of thermal expansion of Ti-doped HA and Ti-alloy substrate.