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Some intermetallic compounds which contain uranium or cerium present heavy fermion characteristics. Take, for example, in the UM₂Al₃ (M=Pd, Ni) family, superconductivity and magnetism coexist and present heavy fermion behavior. This work presents the crystallographic characteristics and physical properties of a new compound of this family; the intermetallic compound UCo₂Al₃. Our initial crystallographic studies performed in a small single crystal show that the structure is hexagonal and similar to the UNi₂Al₃ and UPd₂Al₃ parent compounds. The space group is P6/mmm with a=5.125 Å and c=4.167 Å crystalline parameters. Measurements of resistivity and magnetization performed on the single crystal reveal that the compound is not superconducting when measured at about 1.8 K. The compound is highly anisotropic and features related to Kondo-like behavior are observed. A weak ferromagnetic transition is observed at a temperature of about 20 K.

The electronic structure of the Iridium based L1₂ intermetallic compounds (A₃B) such as Ir₃Ti, Ir₃Zr, Ir₃Hf, Ir₃V, Ir₃Nb and Ir₃Ta, which have wide applications as high temperature structural materials are studied by means of Self-Consistent Tight Binding Linear Muffin Tin Orbital (TB-LMTO) method. These compounds are found to crystallize in the Cu₃Au type structure. The total energies are calculated as a function of volume and fitted to Birch equation of state to find the equilibrium lattice parameter and the bulk modulus. They are tabulated and compared with the available experimental and other theoretical data. The partial number of electrons at A and B sites of these compounds are calculated as a function of volume. We find that there is a continuous transfer of d-electrons from A-site to B-site. The band structure and density of states histograms are plotted. From the DOS histograms, we find that the plots are similar for all the compounds except for Ir₃V. In the case of Ir₃V, we find that there are hybridization between Ir-d like and V-d like states at the Fermi level. Hence, it is predicted that under compression there may be a Lifshitz type of transition in Ir₃V. The cohesive energy, heat of formation and the electronic specific heat coefficient of the compounds are also computed.

Ni–Al intermetallic compounds nanocrystalline thin films were deposited by direct current magnetron co-sputtering from elemental Ni and Al targets. The integrity of the thin films and their elemental compositions were assessed using a scanning electron microscope (SEM) equipped with an energy dispersive spectroscope analyzer. The morphologies of thin alloy films are density and smoothing characterized by atomic force microscope and SEM. The preferred (111) orientation in both as-deposited and annealed films are identified using X-ray diffractometer (XRD). The electrical properties of the alloy films were studied, and show good metallic conduction characteristics. From room temperature to 200°C, the resistance of the thin films are assumed to be linear as a function of varying temperature. All the thin films show a positive temperature coefficient of resistance (TCR). As 1% O₂ was introduced into the vacuum chamber during sputtering, the root mean square roughness of the films increased, grain size turned out to be smaller, and the crystallization process was blocked. The amorphous Al₂O₃ phase was found in XRD patterns. The results of TCR measurement show a different electric conduction mechanism compared with alloy films.

Butt joining of AA6061 aluminum (Al) alloy and 304 stainless steel of 2-mm thickness was conducted using laser–MIG hybrid welding–brazing method with ER4043 filler metal. To promote the mechanical properties of the welding–brazing joints, two kinds of intermediate layers (Al–Si–Mg alloy and Ag-based alloy) are used to adjust the microstructures of the joints. The brazing interface and the tensile strength of the joints were characterized. The results showed that the brazing interface between Al alloy and stainless steel consisted of double layers of Fe₂Al₅ (near stainless steel) and Fe₄Al${}_{13}$ intermetallic compounds (IMCs) with a total thickness of 3.7 $\mu$m, when using Al–Si–Mg alloy as the intermediate layer. The brazing interface of the joints using Ag-based alloy as intermediate layer also consists of double IMC layers, but the first layer near stainless steel was FeAl₂ and the total thickness of these two IMC layers decreased to 3.1 $\mu$m. The tensile strength of the joints using Al–Si–Mg alloy as the intermediate layer was promoted to 149 MPa, which was 63 MPa higher than that of the joints using Al–Si–Mg alloy as the intermediate layer. The fractures occurred in the brazing interface between Al alloy and stainless steel.

Spin-polarized density functional calculations are performed to study the correlation and spin-orbit coupling (SOC) effects in scandium intermetallic compounds viz. ScTM (TM=Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag and Au) using FP-LAPW+lo method. The LDA, LDA+U and LDA+U+SOC exchange-correlation functionals are used to calculate the structural parameters and we found that the LDA+U results are consistent with the experiments. The electronic properties reveal that these compounds are metallic in nature. Correlations effects are determined using the U/W ratio and we found that ScCo, ScIr, ScPd, ScPt, ScCu and ScAg are highly correlated compounds, whereas ScRh, ScNi and ScAu are intermediately correlated compounds. Furthermore, stable magnetic phase for each compound is optimized, which reveals that ScCo, ScRh, ScPd, ScPt and ScCu are stable in ferromagnetic phase, ScIr, ScNi and ScAu are anti-ferromagnetic, whereas ScAg is a nonmagnetic material.

In this paper, thermodynamic and elastic properties of the AlNi and AlNi₃ were investigated using density functional theory (DFT). The full-potential linearized augmented plane-wave (APW) in the framework of the generalized gradient approximation as used as implemented in the Wien2k package. The temperature dependence of thermal expansion coefficient, bulk modulus and heat capacity in a wide range of temperature (0–1600 K) were investigated. The calculated elastic properties of the compounds show that both intermetallic compounds of AlNi and AlNi₃ have surprisingly negative Poisson’s ratio (NPR). The results were compared with other experimental and computational data.

We butt-welded AA6061 aluminum alloy to Ti6Al4V titanium alloy, dissimilar light metals, by using laser-MIG hybrid welding–brazing without grooves. The parameters of the laser and arc were optimized to produce sound joints with good formation and mechanical properties. The microstructure of the layer of intermetallic compounds (IMCs) was investigated by scanning electron microscopy and energy dispersive spectroscopy. We also tested the tensile strength of the joints with and without reinforcement. The morphology and thickness of the IMCs varied throughout the joints. A continuous thin layer of TiAl₃ appeared on the top surface of the Ti6Al4V, on which some rod-like IMCs grew toward the fusion zone. In the upper region of the butt plane, because more heat accumulated there from the high-power laser coupled with the MIG arc, double-layer IMCs with a thickness of $\sim$10.0 $\mu$m formed, composed of TiAl (near the Ti alloy) and TiAl₃ (near the fusion zone). In the lower region of the butt plane, the double-layer IMCs became continuous and uniform, the serrated morphology disappeared, and the thickness of the IMC layer decreased to 4.0 $\mu$m. On the backside of the joint, the thickness of the compound layer (TiAl₃) was about 1.0 $\mu$m. The average tensile strengths of the reinforced and unreinforced joints were 226 MPa and 210 MPa, respectively, which are up to 88% and 81% of the AA6061 tensile strength, respectively.

In this study, the effects of Cu nanoparticles on the melting characteristics, wettability, interfacial reaction and mechanical properties of $\mathrm{\text{Sn}}$–$\mathrm{\text{xCu}}$$(x=0$, $0.3$, $0.7$, $1.0$, $1.5$, $2.0)$ composite solders were investigated. Results show that the properties of the composite solder containing Cu nanoparticles were improved effectively. With the addition of Cu nanoparticles, the melting point of $\mathrm{\text{Sn}}$–$\mathrm{\text{xCu}}$ solder decreased significantly, and the spreading area and the shear strength were increased by 10.3% and 23.2%, respectively. For the performance, the optimal addition of Cu nanoparticles was 0.7%. In addition, the growth of interfacial intermetallic compounds in $\mathrm{\text{Sn}}$–$\mathrm{\text{xCu/Cu}}$ solder joints was inhibited by adding Cu nanoparticles.

Diffusion bonding is an effective method for joining dissimilar materials. In this study, dissimilar metals of MA956 steel and tungsten (W) were diffusion bonded with Ni/Nb composite interlayer. The experiments were carried out at $1050^{\circ }\mathrm{\text{C}}$, 20 MPa for 20 min in vacuum by spark plasma sintering (SPS) technique. The microstructure and mechanical properties of the bonded joints were evaluated. SEM images and the results of elementary composition indicate that no intermetallics formed at Ni/MA956 steel and Nb/W interfaces, but ${\mathrm{\text{Ni}}}_6{\mathrm{\text{Nb}}}_7$ and ${\mathrm{\text{Ni}}}_3\mathrm{\text{Nb}}$ formed at the Nb/Ni interface. Compared with the directly bonded joint between W and MA956 steel, the average shear strength of the joint with Nb/Ni composite interlayer significantly increased to 270 MPa. Although the result of joint residual stresses simulation shows that the maximum residual stress was near the W substrate, the joints with composite interlayer in shear experiments fractured at Nb/Ni interface. The hardness changes along joint interfaces indicate the formation of intermetallic compounds and solid solution phases in the diffusion layers.

We review the complementary roles that ¹¹⁹Sn Mössbauer spectroscopy and neutron diffraction are playing in developing a complete description of magnetic ordering in the R₃ Cu₄Sn₄ and R₃Ag₄Sn₄ intermetallic compound series. We show that the two techniques yield consistent pictures of the order, and in many cases both are essential to obtaining a complete description. The recent neutron diffraction work on Sm₃Cu₄Sn₄, Sm₃Ag₄Sn₄ and Gd₃Ag₄Sn₄ is highlighted.

The structural and magnetoelastic properties of polycrystalline samples of Y₃Fe_27.2Cr_1.8 and Ce₃Fe₂₅Cr₄ intermetallic compounds are investigated by means of X-ray diffraction, thermomagnetic, thermal expansion and magnetostriction measurements in the temperature range of 77–500 K under applied magnetic fields up to 1.5 T. The well defined anomalies observed in the linear thermal expansion coefficient curves are associated with the magnetic phase transitions and presence of small amounts of 1:12 phase in the Ce₃Fe₂₅Cr₄ sample; the latter is also confirmed by AC susceptibility measurements. For Y₃Fe_27.2Cr_1.8, saturation behavior is observed in the anisotropic magnetostriction isotherms near the magnetic ordering temperature (T_C), whereas for Ce₃Fe₂₅Cr₄ compound, saturation starts well below T_C. The additional anomalies observed in the volume magnetostriction isotherms of both compounds are explained based on the anisotropy field in the a–b plane and along the c-axis of the unit cell.

A series of binary rare-earth metal germanides RE₅Ge₃ (RE = La, Ce, Pr and Nd) adopting the Mn₅Si₃-type hexagonal structure is studied. These intermetallic phases show a complex magnetic behavior. Using a modification of the local density approximation (LSDA + U) the magnetic and electronic properties of these compounds are calculated. The spin-orbit coupling (SOC) was included using a full relativistic basis. Besides the structural parameters, bonding characters, total and partial densities of state and band structures are analyzed and compared with the experimental findings.

The structural and temperature reliance manner of the thermodynamic parameters of Ni–Al intermetallic compounds with different pressures is comprehensively studied by executing first-principles calculation using the density functional theory (DFT). The calculated optimized volume and bulk modulus are in good agreement with the experimental and theoretical results at zero pressure. Quasi-harmonic Debye model is adopted to find out the bulk modulus, volumetric thermal expansion coefficient, Debye temperature, Gibbs free energy and enthalpy of Ni–Al intermetallic compounds in different pressure ranges from 0 MPa to 600 MPa and temperature ranges from 0 K to 1200 K. Additionally, special attention is paid to calculate the mutual relationships between the thermodynamic parameters with different pressures and temperatures.

This research is an effort to understand the morphology of the coating produced during hot dipping process in pure zinc bath based on iron–zinc phase diagram. In this investigation, zinc coating on low-alloy steel AISI 4340 samples was applied by hot dipping method followed by an annealing process. Morphological characterizations of the steel surface layer were accomplished by optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectrometry (EDS). Results revealed that the coating is bonded to the steel surface through a sequence of Fe–Zn layers namely alpha ($\alpha )$, delta ($\delta )$ and zeta ($\zeta )$ with uniform sloping hardness profile.

Magnetometry and atomic force microscopy (AFM) were used to study the magnetic and structural properties of the R–Fe–B-type (R = Y, Nd, Gd, Ho) alloys. The alloys were synthesized by means of induction melting. The nanocrystalline state of the R–Fe–B-type alloys was reached, mainly, by melt spinning (MS). A multistage treatment of R–Fe–B-type alloys, which included severe plastic deformation of melt-quenched ribbons and subsequent heat treatment, was also used. The surface morphology of samples was studied in detail to interpret the observed magnetic hysteresis loops of the samples. It was found that the type of rare earth ion and treatment methods had the most important influence on the microstructure and magnetic properties.

Chemical reaction and formation of intermetallic compounds at the interface are widely believed to have a beneficial effect on the wetting in metallic systems. However, we demonstrated in this study that it might be an erroneous or at least imperfect viewpoint, which is misled by the presence of native oxide film of metals. Using a dispensed sessile drop technique together with substrate pre-annealing treatment in high vacuum, we found that the wetting of clean Cu, Ni and Fe surfaces by clean Sn droplets is almost independent of interfacial reaction; whereas, for oxidized surfaces, the interfacial reaction plays a significant role in the wetting through the disruption of the oxide film covering the liquid or/and solid surface(s), making their intimate contact possible.