this case, Cu content, also determined by EDX, in the alloy matrix phase were slightly higher. This indicates that only small amounts of these elements are necessary to induce anisotropy, or the right amount of alloying addi- tion is necessary for achieving high anisotropy. It is possible that the addition of large amounts of any element will create a large number of non-disproportionated regions and dilute the matrix phase with the appearance of new phases. The effect of Ti, V, Cr, Mo, Al, Si and P additions on the magneticproperties of bonded magnets have also been reported previously .
made from high purity elements by induction melting furnace, and then the techniques of making powder were ball-milling and jet-milling, respectively. The degassed powder compaction were sintered at 1200-1220 ℃ for 1 h and then homogenized at 1150-1180 ℃ for 1.5 h. The subsequent aging was at 800~860 ℃ for 10 h, followed cooling to 400 ℃ at a rate of 0.8 ℃/min, aging at 400 ℃ for 5 h and finally quenching to room temperature by water. Meanwhile, the magnets made of ball-milling and jet- milling hereafter designated as type-A magnet and type-B magnet, respectively.
powder sample was ﬁxed with vacuum grease on a copper sample holder. The diffraction data were taken at 20° ¯ 2ª ¯ 85° with a step size of 0.01°. We conﬁrmed that the powder sample was not removed by magnetic force until the measurement under magnetic ﬁ elds was completed. For determining the X-ray re ﬂ ection indices and the crystal structure, the observed diffraction patterns were analyzed by comparison with calculated patterns using a Rietveld program (RIETAN-FP 17) ).
glassy alloy has a unique glassy structure with the features of (1) a more highly dense random packed atomic configuration, (2) new local atomic configurations and (3) long-range ho- mogeneity with attractive atomic interaction. The new struc- ture typical for the bulk glassy alloys with a large supercooled liquid region has been pointed out 28) to exhibit a lower coer- cive force and a higher maximum permeability because of the more homogeneous glassy structure which leads to more easy movement of magnetic domain wall. The unique glassy struc- ture in the present Fe-based alloy may be another important factor for the achievement of the good soft magnetic prop- erties in the sintered bulk samples. The success in forming the bulk glassy alloy with good soft magneticproperties by the combination of the large supercooled liquid region before crystallization and the unique new glassy structure is encour- aging for future application as a new type of soft magnetic bulk material.
Cu40 mass%Zn0.52 mass% Cr (Cu40Zn0.5Cr) pow- der and 60 mass% Cu40 mass% Zn (Cu40Zn) powder were prepared by the water atomization process (Nihon atomized metal powders Co.). Microstructures of raw powders observed by scanning electron microscopy (SEM, JSM- 6500F: JEOL) are shown in Fig. 1. The particles of all raw powders show irregular shapes which have the typical morphology prepared by water atomization process. Figure 2 shows the particle size distribution of Cu 40Zn 0.5Cr powder and Cu 40Zn powder by using laser scattering particle size distribution analyzer (LA-950: HORIBA). Mean particle size of Cu40Zn0.5Cr and Cu40Zn were 120 and 171 µm, respectively.
The temperature dependence and the stability and cost of materials are to be considered besides their magneticproperties. The dc and ac properties provided characteristics suitable for different types of applications. Generally high electrical resistivity, high mechanical strength, good corrosion resistance, and absence of crystalline anisotropy, structural defects and grain boundaries characterize amorphous ribbons. The magneticproperties such as saturation flux density, Curie temperature, magnetostriction and induced anisotropy can be controlled by the alloy composition and a subsequent heat treatment. The high electrical resistivity and the small thickness of the melt-quenched ribbons lead to low eddy current losses. The low hysteresis losses, results in very low core losses are of interest for power electronics at high frequencies. For application in small electronic devices, the amorphous ribbons have somewhat poorer losses than the conventional Fe-Ni-B ribbon. The design optimization requires lower cost of amorphous ribbons, higher induction compared to Fe-Ni-B ribbons. Amorphous ribbons have many refined applications also like development of magnetic bubbles for computer memory, amorphous superconductors etc. Research in the theoretical understanding, development and application of amorphous ribbons can thus be profitable, especially at its present new phase.
The eﬀect of magnetic ﬁeld on deformation properties was investigated by placing compression specimens between paired NdFeB permanent magnets (8 mm or 14 mm in diameter) in a parallel conﬁguration of magnetic ﬁeld with respect to the compression direction. Figure 1 is a schematic illustration of compression test apparatus showing the parallel conﬁguration, where paired magnets were mounted on the top and bottom compression grips. Two-dimentional distributions of magnetic ﬁelds created by paired NdFeB magnets were measured and the results were drawn in Fig. 2. In this ﬁgure, the position of specimens is indicated by dotted lines. As seen, magnetic ﬁelds applied are center-symmetric, ranging (a) from 0.2 to 0.5 T for paired magnets of 8 mm in diameter and (b) from 0.4 to 0.6 T for paired magnets of 14 mm in diameter. When compression specimens are set between the paired magnets, as seen in Fig. 2, large portion of the specimens are under a ﬁeld of 0.2–0.3 T for 8-mm magnets and under that of 0.4–0.5 T for 14-mm magnets. After compression, specimens were all unloaded and de- magnetized followed by heating up to 423 K for shape recovery.
There has been intensive research on the characterisation and application of carbon nanotubes for next-generation electronic devices . Ballistic conduction along single- walled metallic nanotubes is predicted theoretically and has been experimentally verified. Clearly, this has enormous impact for electronic devices fabricated using these remark- able materials, but there are problems in characterising the electronic properties using conventional (i.e. DC) techni- ques. This is mainly due to the need to make electrical con- tacts with the ends of the nanotube, which suppresses the measured conductivity, and is further complicated by inter- tube contacts. For example, it has been found that thin film samples have sheet resistances limited by the large junction resistances between adjacent nanotubes .
boric acid, 1 gr.l -1 ascorbic acid at 30 º C. Electrodeposition was performed in a simple electrochemical cell with two electrodes; the sample and a graphite rode were used as working and counter electrodes, respectively. The reduction/oxidation voltage, reduction/oxidation time and off-time between pulses were chosen to be 13V, 2.5 ms and 20 ms, respectively. The length of nanowires was adjusted by controlling the deposited charge. Figure 1 shows current/voltage variations during the deposition process. The effect of length variation (~ 1.9, 7.12, 8.3, 9.5 and 13.3 µm ) on the magneticproperties of the electrodeposited nanowires were studied .
After laser cladding, the specimen is cut into a plurality of samples along the scanning direction, with No. 400, No. 800 and No. 1200 sandpaper for pre- grinding and polishing. The microstructure and properties of modified layers were studied by XRD, SEM, micro hardness tester and electrochemical worksta- tion, and compared with the untreated samples. Hardness of the load is 50g and the loading time is 15 s, between the spacing of 250 μm; corrosion electrochemi- cal workstation is 3.5% (mass fraction) NaCl solution, a constant temperature of 25˚C, the system adopts saturated calomel electrode as reference electrode, pla- tinum electrode as auxiliary electrode, the sample for 1 hours in the static me- dium. Until the system is stable, determinate electrochemical polarization curves, the initial potential scanning potential for −2 V, scan termination poten- tial is 1 V, the scan rate is 1 mV/s. When measuring the electrochemical imped- ance spectrum, choose the measurement under the self-corrosion potential, the frequency range is set to 0.01 - 100,000 Hz.
Owing to the deformation, the morphology of the powder changes from a spheroidal shape to an irregular shape. The deformed powders also weld together to form large powder particles. Moreover, ball-powder collision and ball-ball sliding can increase the powder temperature, which results in dissolution of the eutectics towards the primary ¡-Al phase, and consequently decreases the eutectic amount. The ball-milled powders possess high-density dislocations, which result from the plastic deformation during the ball milling. 3) These dislocations provide convenient channels for further dissolution of the eutectic phases. The powders are merely mechanically consolidated during cold pressing, and thus, it is dif ﬁ cult to eliminate pores from the green compacts (Fig. 1). Therefore, the pore evolution during partial remelt- ing should be examined.
MnBi nanoparticles can be used to produce hybrid magnets such as MnBi/NdFeB leading to the high coercivity, thermal stability and large operating temperature range for the magnets. 9,10) However, the formation of the single MnBi low temperature phase is very difﬁcult, because of the segregation of Mn from the MnBi liquid at the temperature of 719 K and the slow diffusion of Mn through MnBi in solid state. Therefore, the optimization of fabrication technology to create a pure MnBi low temperature phase is still concerned to study. Several methods, which have been utilized to fabricate the Mn-Bi magnetic materials, include arc-melting, spark plasma sintering, melt-spinning and high energy ball milling. 1116) Among them, the high energy ball milling method can be used to create desired microstructures for the material. In this work, we investigated inﬂuence of technological conditions such as milling environment, mill- ing time, annealing temperature+ on structure and magneticproperties of Mn 55 Bi 45 nanoparticles prepared by high energy
In this article effect of coating time and incorporation of WC nano-particle in nano-composite PEO coatings fabricated on AZ31B Mg alloy is studied. Samples coated in nano-particle suspension had 10 to 17 volts lower sparking potentials. Addition of nano-particles decreased mean pore diameter of coatings from 8.48 to 6.57 µm and average porosity fraction from 18.80% to 12.85 % for coatings without and with nano-powders respectively. There was no agglomeration of nano-powders in structure of coatings. Time pass during coating process in samples containing nano-powders increased nano-powder absorption from 0.99 % to 2.68%. Addition of WC nano-powders to coatings caused only slight improvement in corrosion behavior of samples. Addition of nano-powder increases average COF up to 0.19. Nano-powder presence not only decreases wear track width, but also decreases wear rate from 30.65 to 20.43 mg/(m.N) for samples without and with nano-powder respectively. Particle agglomeration or oxidation in wear track was not observed. With addition of nano-powder average roughness increses from 1.28 to 1.60 µm for samples without and with nano-powder respectively due to nucleator role of nano-powders.
This review on the nano-biomedical applications of nano- particles focuses on tailoring new materials through facile synthetic methods or refining conventional synthetic routes to obtain reproducible MHAp nanoparticles with optimum morphology (shape and size), stability, and biocompatibility, in addition to superior magnetic saturation. The ultimate goal of using MHAp in biomedicine is to help patients, by introducing selective treatments through guided drug delivery systems. In addition to drug delivery, the use of multifunctional MHAp in simultaneous imaging, hyper- thermia, and gene/plasmid delivery is going to drastically improve the diagnosis and therapy of diseases. HAp coating over magnetic nanoparticles offers several advantages such as excellent biocompatibility and high stability in a broad pH and temperature range; moreover, it protects nanoparticles such as polymers from agglomeration. The stability of HAp at high pH range helps in regulating drug release kinetics during a pH-mediated drug delivery inside the body sys- tem. In regenerative tissue engineering applications, using MHAp nanoparticles to prepare scaffold materials stimulates remote actuation for regulating bioactive molecules and magneto-mechanical cell stimulation, cell seeding, and cell patterning. Besides the advances, the exhilarating milestones made in these areas seek attention for critical evaluation before being regularized in the medical sector. However, we trust that the coming few years will see huge advances in the number of MHAp-based diagnostics and medicines being used in the clinics. This review critically revealed the recent status, efficiency, and future prospects of MHAp nanomaterials in biomedical applications.
The same change of pseudo yield stress is followed also by other stresses: true yield stress and tensile strength. Higher mechanical resistance of the alloy treated at lower temperatures is the consequence of an interactive action of several factors. The strength of a two-phase structure that apart from α-phase also contains mechanically- induced martensite, is determined, among other things, by the hardness of structural constituents, their share, distribution and size. Since the hardness of martensite depends on the hardness of austenite, and at lower betatisation temperatures, austenite is somewhat harder, the alloy also shows higher mechanical resistance additionally contributed by reinforced precipitation processes i.e. numerous boundaries of anti-phase areas as well as the formation of sub-boundaries within austenitic crystals.
Products made from metallurgy powder process are considered good products if they have high density and low porosity values. It means that the products have experienced good densification so that it increases their mechanical properties. However, because the bronze bearings were applied to porous materials that wear-resistant, the porous was needed as a place to store a lubricant to reduce friction between components [1, 2]. The higher sintering temperature made the tendency of mechanical properties such as density also increased . From the Figure 3, it can be seen a relationship between density and sintering temperature in which the density increased to the optimum temperature (800°C). It was because when liquid phase sintering, there was rearrangement in liquid phase of Sn and
Dependence of the tensile properties of hot extruded Cu0.5Ti/CNTs composite on CNTs contents was shown in Fig. 3, where the result of P/M extruded pure copper was also shown. Cu 0.5Ti without CNTs had 308.3 MPa UTS, 202.1 MPa yield stress (YS) and 38.9 % elongation. YS and UTS of extruded Cu0.5Ti/CNTs decreased with increasing CNT contents compared to the monolithic Cu0.5Ti alloy. In case of the conventional high strength copper alloys, the elongation was decreased with increasing the tensile strength by aging precipitation behavior of alloying elements. On the other hand, the elongation of Cu0.5Ti/CNTs composites was over 30%. It was almost same as that of the monolithic Cu0.5Ti alloy. Cu0.5Ti with 0.19 mass% CNTs had 308.3 MPa UTS, 202.1 MPa YS and 38.9% elongation. Y of Cu0.5Ti/0.19CNTs composite was 2 times as that of pure copper. The electrical conductivities of the monolithic Cu 0.5Ti and Cu0.5Ti/CNTs composites were shown in Fig. 4. Monolithic Cu 0.5Ti had 42.5 IACS % almost same as Cu 0.5Ti materials by ingot metallurgy (I / M) (39.8 IACS % ). This result showed that powder bonding of monolithic Cu 0.5Ti sintered material was strong and the effect of oxide ﬁlms of primary particle boundaries on electrical conductivity
The latter 0%Cu alloy rod exhibits a sequent change in glass transition, supercooled liquid and then crystallization. On the other hand, the former 1%Cu-containing alloy exhibits dis- tinctly separated exothermic peaks, indicating that the crys- tallization proceeds through at least two stages in the absence of the supercooled liquid state. The temperature interval be- tween the main two exothermic peaks is as large as 105 K. The multi-stage crystallization mode is in agreement with that for the Fe 73 . 5 Si 13 . 5 B 9 Nb 3 Cu 1 (FINEMET) alloy 22) with differ-
Nowadays, the usage of adhesive bonding in the industries such as automotive, aerospace, construction and marines are frequently been heard. Before the development of adhesives bonding, other traditional metal working methods have been used to attach the surface of structural, material and component of a substance. The examples are welding, bold and nut, fastener, rivets and brazing. Adhesives bonding on fatigue analysis have not been discovered deeply since before. In this study, I will do a research on adhesives bonding by fatigue analysis which the type of adhesives is epoxies with an addition of aluminium powder at the epoxy. The fatigue analysis will be determined by using S-N Curve, in terms of nominal stress (S) vs number of cycles to failure (N). The fatigue life is the number of cycles to failure at specified stress level and the fatigue strength is the stress below which failure does not occur. Only the fatigue life will be observed throughout this study.
The sample surface and grain structures after molding were observed by SEM. The crystal structure appeared relatively uniform and compact after molding (Fig. 3a). However, there were also visible flaws under 1000X magnification, like the local area uplift phenomenon seen in Fig. 3b. The reason for this was that, during the forming process, impurities were present in the powder, which rendered the powder uneven or led to the formation of tiny masses, resulting in local volumes that lack sufficient density. The microstructural orientation of the CoCr alloy showed no obvious macro-defects, such as pores and cracks on the surface of the sample (Fig. 3c). This showed that densification of the formed part or piece under this method was high.