Papers by Keyword: Intermetallic Compound

Abstract: This study investigates the bonding properties of transient liquid phase diffusion bonding using Cu/Sn electroplated films. A Cu substrate was electroplated with Cu and Sn films, followed by TLP bonding with a Ni substrate at 280°C under air atmospheric conditions without bonding pressure. Bonding times of 1, 3, and 30 min were employed to evaluate the effect of bonding duration on interfacial microstructure and shear strength. Cross-sectional microstructural analysis using EPMA revealed the formation of a Cu–Ni–Sn reaction layer at the bonded interface, with the thickness of this layer increasing as bonding time increased. Voids were observed at all bonding times, particularly at 30 min, where extensive void formation led to incomplete bonding. Shear test showed that shorter bonding times yielded higher average strengths, while longer bonding times resulted in a reduction due to void-induced degradation. Fracture surface observations confirmed that failure occurred within both the Sn and reaction layer, regardless of bonding time.

Abstract: This study evaluates the fusion of 6061 Aluminum alloy with Mild Steel — materials known for their superior technical attributes yet distinct mechanical and physical properties — through Metal Inert Gas Arc Welding (MIG). The objective is to create a joint of dissimilar materials that boasts a robust strength-to-weight ratio, suitable for sectors like automotive, aviation, aerospace, and marine. A significant hurdle in this welding technique is preventing the creation of fragile intermetallic compounds (IMCs) that could compromise the joint's integrity and depth of penetration. The research outlines a method for adjusting welding parameters and setups to curtail the IMC thickness at the interface of the mild steel, which was observed to be between 2-6 μm in the conducted tests. The findings suggest that the MIG welding-brazing method can successfully form joints of dissimilar materials with mechanical strengths on par with other welding techniques. Additionally, variations in the maximum IMC layer thickness were noted with changes in welding parameters such as voltage, wire feed rate, gas shielding, and the configuration of the mild steel, as evidenced by the experiments. Notably, an increase in wire feed rate led to a more substantial IMC layer due to the higher heat input and prolonged arc time, facilitating more intense diffusion and interaction between the aluminum and steel. An exponential increase in the IMC layer thickness was recorded on the mild steel side with rising voltage, whereas the aluminum side's IMC layer thickness remained consistent.

Abstract: The paper presents a study of the formation process of cermet powders based on TiAl intermetallic with the addition of non-metallic refractory compounds. Non-metallic refractory compounds B4C, BN, SiC, and Si₃N4 were chosen as strengthening components, improving the mechanical properties and resistance to high-temperature oxidation of TiAl-type intermetallic coatings. The composition of the initial mixtures was selected based on thermodynamic analysis of the interaction between TiAl intermetallic and non-metallic refractory compounds. As a result of the mechanochemical synthesis of powder mixtures, 73TiAl-27B₄C, 69TiAl-31BN, 88TiAl-12SiC, and 83TiAl-17Si₃N4 (wt. %) cermet powders are formed, consisting of titanium aluminide (TiAl, Ti₃Al) phases and refractory compounds of aluminium (AlB2 and AlN) and titanium (TiB₂, TiC, TiN, Ti5Si₃). The conglomeration technology of produced cermet powders has been developed to enhance fluidity. Using conglomerated powders will provide their constant feed to the high-temperature jet and the formation of dense coatings during thermal spraying.

Abstract: Nitrides of ‘2:17’ - type based on rare earth metals and iron are of interest as promising magnetic materials for the development of high-energy permanent magnets. The magnetic properties and phase composition of the starting compound Sm_1.8Er_0.2Fe₁₇, nitride Sm_1.8Er_0.2Fe₁₇N_2.1 and its crushed powders have been investigated. The magnetic measurements of the samples were studied in magnetic fields up to 70 kOe at room temperature. It was found that the introduction of nitrogen atoms into the crystal lattice of the substituted composition (Sm,Er)₂Fe₁₇ in combination with the effect of high-energy milling of nitride leads to an increase in the saturation magnetization (σ_S) and coercive force (H_C).

Abstract: The different composition material of copper substrate significantly affects the intermetallic compound (IMC) formation and the solder joints durability. This study was conducted on the interfacial reaction between lead-free solder and the different copper substrates via reflow soldering. The selected substrate is copper (Cu) and copper-beryllium (Cu-Be). The lead-free solder involved is Sn-3.8Ag-0.7Cu (SAC3807) solder ball with a diameter of 700 μm. All the samples were subjected to the isothermal aging process. The material characterization and analysis on the IMC formation were examined by scanning electron microscopy (SEM), optical microscope (OM), and energy dispersive X-ray analysis (EDX). After the reflow process, the result revealed that Cu₃Sn, Cu₆Sn₅ IMC layer formed at SAC3870/Cu and SAC3870/Cu-Be interface. The changes to a rod-like shape Cu₆Sn₅ and irregular needle-shaped Cu₃Sn₄ occur after the aging treatment on SAC3870/ Cu. Meanwhile, the IMC layer for SAC3870/Cu-Be shows a rod-like shape transformed into a blocky-like shape Cu₆Sn₅ and Cu₃Sn₄ diamond-shape. This result indicates that Ag₃Sn nanosized was formed on the intermetallic surface during the aging process for both SAC3807/Cu and SAC3807/Cu-Be. The Ag₃Sn nanosized element at SAC3807/Cu-Be is many compared to SAC3807/Cu. In addition, IMC thickness for SAC3807/Cu-Be shows a thicker layer than SAC3807/Cu. Lastly, in this research, the element of Be in SAC3807/Cu-Be cannot be defined because the beryllium element is not easily detected as the percentage was very low.

Abstract: Magnetic properties of the R₂Fe₁₇ compounds are sensitive to the atomic substitutions and interstitial absorption of nitrogen. In our work, both were combined and their effect on the magnetization behavior of Er₂Fe₁₇ compound in magnetic fields up to 58 T was studied. Er₂Fe₁₇N₂, Sm_1.2Er_0.8Fe₁₇N₂ and Sm_1.8Er_0.2Fe₁₇N_2.1 nitrides were prepared. Magnetization measurements were carried out, mainly on powder samples (excluding Er₂Fe₁₇ single crystal). Nanopowders of Sm_1.2Er_0.8Fe₁₇N₂ were obtained by mechanical grinding. The grinding time was varied from 0 to 60 minutes. The strength of the inter-sublattice coupling in samples is estimated by analyzing high-field magnetization data.

Abstract: The conditions for the synthesis of Al-Cr-W alloys during the aluminothermic reduction of a mineral tungsten concentrate - scheelite were considered. The alloys were identified as an aluminum matrix by the methods of elemental and X-ray phase analyzes. It is shown that the alloy synthesized from scheelite concentrate contains small amounts of iron and oxygen impurities (1.2 wt. %). It has been established that the alloys have a composite structure: inclusions of continuously solid solutions based on chromium and tungsten, as well as chromium aluminides Al₃(Cr, W, Fe)2, which have increased microhardness values (12.9 GPa) are distributed in the aluminum matrix.

Abstract: Nanocrystalline Ni₇₅Fe₂₅ (Ni₃Fe) powders were prepared by mechanical alloying process using a vario-planetary high-energy ball mill. The intermetallic Ni₃Fe formation and different physical properties were investigated, as a function of milling time, t, (in the range 6 to 96 h range), using X-Ray Diffraction (XRD) and Mössbauer Spectroscopy techniques. X-ray diffraction were performed on the samples to understand the structural characteristics and get information about elements and phases present in the powder after different time of milling. The refinement of XRD spectra revealed the complete formation of fcc Ni (Fe) disordered solid solution after 24 h of milling time, the Fe and Ni elemental distributions are closely correlated. With increasing the milling time, the lattice parameter increases and the grains size decreases. The Mössbauer experiments were performed on the powders in order to follow the formation of Ni₃Fe compound as a function of milling time. From the adjustment of Mössbauer spectra, we extracted the hyperfine parameters. The evolution of hyperfine magnetic field shows that the magnetic disordered Ni₃Fe phase starts to form from 6 h of milling time and grow in intensity with milling time. For the milling time more than 24 h, only the Ni₃Fe disordered phase is present with a mean hyperfine magnetic field of about 29.5 T. The interpretation of the Mossbauer spectra confirmed the results obtained by XRD.

Abstract: In order to weld dissimilar materials with dramatically different properties such as aluminum and steel, friction stir welding (FSW) offers many advantages over conventional fusion welding techniques. However, producing strong and durable FSW joints requires full characterization of these joints including metallurgical and mechanical characterization. In this work, many process parameters and two different tools are put to test and the resulting FSW joints are characterized. Their mechanical strength is investigated in tension with respect to intermetallic compounds content analyzed using SEM coupled to EDX. The soundest 2mm thick joints recovered 55% of the strength of the original un-welded metal whereas in the case of the 3mm thick joints 47% of the strength could only be recovered in the best case. It was revealed that as the content in intermetallic compound increases the strength of the joints decreases. Additionally, it was found that the higher the mechanical deformation, the more these compounds are abundant; in other words, intermetallic compounds were largely found in the middle and bottom sections of the 3mm thick samples which is where the threads of the pin do most of their work. The compositions of these intermetallic phases along the abutting surfaces is also proposed based on the elemental composition of Fe and Al as detected by the scanning electron microscopy.

Abstract: This study is dedicated to investigating contact melting, including cases of electrotransport is a Sn-Bi system after introduction of a small admixture of indium. It has been shown that the dopant ambiguously influences the rate of the contact melting. The structure of obtained alloys is strongly non-uniform and abounds with dendritic forms. An attempt is made to explain the results.