Intermetallic Composites Research Articles

Effect of Er content on the interfacial microstructure, shear properties and creep properties of Sn58Bi joints

The influences of Er content on the interfacial microstructure shear properties and creep properties of Sn58Bi joints were investigated in this study. The intermetallic compound composition of Sn58Bi-xEr/Cu was Cu6Sn5 compound. The addition of Er suppressed the activity of Sn element, decreased the driving force for the growth of Cu6Sn5 intermetallic compound and decreased the thickness of Cu6Sn5 intermetallic compound layer. The shear properties and creep durability of Sn58Bi-xEr/Cu welded joints were improved to a certain extent. At the Er content of 0.1%, the shear strength and creep durability properties of the solder alloy are relatively optimal. When wt%Er was more than 0.1%, with the increasing Er content of rare earth elements, the internal organization of the joint interface is coarsened, and the flatness of the IMC layer at the interface is reduced, which leads to the decrease of the creep performance of the final joint.

Changes in the microstructural state of Ti-Al-Nb-based alloys depending on the temperature cycle during spark plasma sintering

Abstract This article presents results of the study on the dependence of the structural-phase state of alloys based on Ti-12.52Al-43.08Nb system (wt.-%) on the temperature of spark plasma sintering. It has been established that spark plasma sintering of Ti-Al-Nb alloys under the temperature of 1500 °C resulted in melting the aluminum component of the mixture that, in turn, negatively affects the quality of ready products. It has also been shown that stepping up the sintering temperature from 1000 °C to 1300 °C leads to increasing volume fraction of O-phase up to 49.63 % due to rapid precipitation of O-phase from B2-phase and Ti3Al-phase. It has been revealed that intermetallic composites obtained under the temperature of 1300 °C are characterized by a dominant two-phase В2+О structure which is more suitable for strengthening sorption properties of hydrogen-storing materials based on Ti-Al-Nb.

Refractory Metal (Nb) Intermetallic Composites, High Entropy Alloys, Complex Concentrated Alloys and the Alloy Design Methodology NICE-Mise-en-scène † Patterns of Thought and Progress.

The paper reflects on the usefulness of the alloy design methodology NICE (Niobium Intermetallic Composite Elaboration) for the development of new Nb-containing metallic ultra-high-temperature materials (UHTMs), namely refractory metal (Nb) intermetallic composites (RM(Nb)ICs), refractory high entropy alloys (RHEAs) and refractory complex concentrated alloys (RCCAs), in which the same phases can be present, specifically bcc solid solution(s), M5Si3 silicide(s) and Laves phases. The reasons why a new alloy design methodology was sought and the foundations on which NICE was built are discussed. It is shown that the alloying behavior of RM(Nb)ICs, RHEAs and RCCAs can be described by the same parameters. The practicality of parameter maps inspired by NICE for describing/understanding the alloying behavior and properties of alloys and their phases is demonstrated. It is described how NICE helps the alloy developer to understand better the alloys s/he develops and what s/he can do and predict (calculate) with NICE. The paper expands on RM(Nb)ICs, RHEAs and RCCAs with B, Ge or Sn, the addition of which and the presence of A15 compounds is recommended in RHEAs and RCCAs to achieve a balance of properties.

Detailed investigation of TiN effect on hybrid intermetallic composites manufactured by combined sinter + forging method

Hybrid intermetallic composites (HICs-aluminum based matrix, new hybrid design) reinforced with titanium nitride (TiN) and alumina (γ-Al2O3) were designed and manufactured through the innovative combined method of sinter + forging. This method results in highly dense materials with, in general, improved mechanical properties. In the composites TiN content was varied (10, 20 and 30 wt %) but γ-Al2O3 content was kept constant at 10 wt%. Additionally, 5 wt% each of Cu and Ni were mixed in to improve processing of the composites. The mechanical properties were specified by different destructive test methods (wear performance, micro hardness, quasi-static compression, three-point bending tests). Wear performance was investigated by scratch experiments. Scanning electron microscopy (SEM) was used to determine the microstructure, interface characteristics and the fracture surfaces. The SEM analysis yielded that TiN powders were located at the grain boundaries and this can be attributed to the improvement observed in the mechanical properties and wear performance with the addition of TiN.

Bimetallic Pd/Sn-based Nanoparticles and their Catalytic Properties in the Semihydrogenation of Diphenylacetylene.

Multimetallic nanoparticles often enhance the catalytic performance of their monometallic counterparts by increasing reaction rates, catalyst selectivity, and/or stability. A prerequisite for understanding structure‐ and composition‐associated properties, however, is the careful design of multimetallic nanoparticles with various structures and compositions. Here, bimetallic Pd/Sn‐based nanoparticles are prepared with a tunable composition and structure exploiting ionic liquids (ILs) as reaction medium (i. e., methyltrioctylammonium bis(trifluoromethylsulfonyl)imide). The nanoparticles are obtained in a one‐pot synthetic procedure by reducing the metal salt precursors with triethylborohydride in the IL. The results show that the reaction parameters, in particular the nature and ratio of the Pd2+/Sn2+ precursors as well as the reaction temperature, influence NP formation and composition. X‐ray diffraction with Rietveld analysis and transmission electron microscopy are employed to determine NP size and phase composition. Under optimized reaction conditions Pd2Sn or PdSn nanocrystals are formed as single‐phase products after introducing an additional annealing step at 200 °C. Nanocrystals with intermetallic composition reveal enhanced catalytic properties in the semihydrogenation of diphenylacetylene which was used as a model reaction.

Microstructural characterization of grade 300 and grade 350 maraging steels and electrochemical study in hydrofluoric solution

The electrochemical behavior of solution-annealed grade 300 and grade 350 maraging steels subjected to two different aging temperatures in an aqueous hydrofluoric acid (HF) medium was evaluated. The microstructural and hardness studies showed the effects of the chemical composition and heat treatments on the material properties. Although it is not possible to observe them, the fine intermetallic composites deposited during aging allow a significant increase in the hardness of materials, which was reduced when aged at 560 °C, where there was formation of reverted austenite. The results showed that, in both steels, solution-annealed samples that were not aged showed a better corrosion behavior than the aged samples. The reversion of austenite during aging at temperatures above 560 °C increases the phase limits and its susceptibility to corrosion. The greater amount of cobalt and titanium in grade 350 maraging steel increases the amount of fine intermetallic precipitate rich in molybdenum and titanium during aging, therefore improving its mechanical properties, but also reducing its corrosion resistance.

Manufacturing and research of complex Al-12Ti-8Zr master-alloy structure and efficiency

The paper presents a method of obtaining and further study of a complex master-alloy, based on aluminum, which contains a total 20 %wt. of modifying components – titanium and zirconium. The master-alloy was obtained under the conditions of electron beam casting technology by gradual fusion of metal components and subsequent casting in the mold under vacuum conditions. The obtained master-alloy is characterized by an inhomogeneous coarse-grained structure. Intermetallic phases Al3(Ti, Zr) are characterized by a tetragonal structure of the crystal lattice and occupy 50 % vol. of the resulting master-alloy. In the composition of intermetallics, zirconium replaces about 25 % of titanium. Modification of AlSi5Cu4 alloy by the obtained master-alloy showed that the modifying phase Al3(Ti, Zr) is able to decompose and dissolve in melts of such alloys and per-forms its germinating and grain-refinement function. In this case, in the rapidly crystallized sample of the modified alloy, the solid solution based on aluminum contains only titanium and a small amount of copper, and in the crystallized – slowly con-tains both titanium and zirconium. The grain sizes of the primary solid solution based on aluminum in both samples can be estimated as the same. Titanium is also present in small amounts in iron-containing Al5SiFe needle-like phases. Zirconium is found mostly in eutectic zones, which contain both silicon and copper-enriched zones. Wider and uniform zones of eutectic are observed in the sample, crystallized with slow speed. It is determined that large particles of the modifying phase during the staying in a melt can be partially dissolved, giving part of the titanium and simultaneously react with silicon, forming more refractory intermetallic particles Al4(Ti, Zr)3Si5. The obtained data indicates the potential suitability and simultaneous need to grind the structure of such master alloys.

Influence of Intermetallic Compounds on Age Hardening of Gasoline Pistons in Engine Operations

Intermetallic precipitates hold the tensile strength of alloy at elevated temperature along with enhanced mechanical and thermal properties. In this research work, we have implemented the new material development of Al-Si alloys with Fe-rich intermetallic precipitates for piston application in order to study the influence of intermetallic compounds (IMCs) on piston performance under engine operations in such a way that pistons with three different intermetallic compositions namely type A, type B and type C were developed to investigate the influence of IMC on age hardening. Three IMC pistons were installed in the engine and allowed to run for six consequent engine operations (1-6 hrs). After the designated hours of engine operation, piston was dismantled from the engine and cut sectioned for aging characterization. Hardness, an indicator of age hardening and thermal stability of the material, was measured at various piston zones such as crown, ring land, top land, skirt and gudgeon pin boss. These hardness values reflect the tendency of age hardening of pistons. It was found that higher IMC density piston alloys (type B and type C) showed the enhancement in tensile strength and hardness about 8 and 13%, respectively. Aging behavior of type B and type C piston zones has been predicted as better due to presence of high dense intermetallic compounds in comparison with type A piston. DSC testing showed that type B and type C have longer precipitation than that of type A piston. Type B and type C alloys have exhibited 20-40% higher specific heat capacity than type A piston. It was found that the high dense star-/Chinese script-like IMC has influenced the Al-Si piston alloy to enhance its properties and piston performance as well.

The effect of process parameters of gas-dynamic spray on generation of brass-type coating structure

The study results have shown the effect of coating temperature and contact ratio on generation of phase structure of the coating based on the mixture of Cu and Zn particles and Al2O3 applied by cold gas-dynamic spray method. The x-ray diffraction and micro-spectral analyses have shown the presence of copper and zinc in the structure and generation of electronic compound based on CuZn3 (e – phase) and Cu5Zn (γ – phase), which is preconditioned by copper diffusion into zinc. The mass fraction of intermetallic compositions in the coating structure depends on the coating temperature and contact ratio, it reaches 12% and 33%. The analysis of surface processing by solid and plastic particles flow has shown the effect of copper particles deformation on diffusion rate.

Microstructure and Properties of As-Cast and Heat-Treated 2017A Aluminium Alloy Obtained from Scrap Recycling

The continuous increase in the consumption of aluminium and its alloys has led to an increase in the amount of aluminium scrap. Due to environmental protection, and to reduce the costs of manufacturing aluminum in recent years, a lot of research is devoted to recycling of aluminum alloys. The paper presents the results of research concerning the possibility of manufacturing standardized alloy 2017A from commercial and post-production scrap by continuous casting. Obtained from recycling process ingots were subjected to analysis of chemical composition and intermetallic phase composition. Based on the results of light microscopy (LM), scanning electron microscopy + electron dispersive spectroscopy (SEM + EDS), and X-ray diffraction (XRD) the following phases in the as-cast state were identified: θ-Al2Cu, β-Mg2Si, Al7Cu2Fe, Q-Al4Cu2Mg8Si7, and α-Al15(FeMn)3(SiCu)2. During solution heat treatment most of the primary precipitates of intermetallic phases, like θ-Al2Cu, β-Mg2Si, and Q-Al4Cu2Mg8Si7, were dissolved in the solid solution α-Al, and during natural and artificial aging they precipitate as strengthening phases θ-Al2Cu and Q-Al4Cu2Mg8Si7 with high dispersion. The highest hardness—150.3 HB—of 2017A alloy was obtained after solution heat treatment from 510 °C and aging at 175 °C. In the static tensile test the mechanical (Rm and Rp0.2) and plastic (A5) properties were determined for 2017A alloy in the cast state and after T4 heat treatment. The highest strength properties—tensile strength Rm = 450.5 MPa and yield strength R0.2 = 268.7 MPa with good relative elongation A5 = 14.65%, were obtained after solution heat treatment at 510 °C/6 h/water quenching and natural aging at 25 °C for 70 h. The alloy manufactured from recycled scrap is characterized by relatively high mechanical properties.

WEAR ANALYSIS OF ALUMINUM–NICKEL INTERMETALLIC SURFACE COMPOSITE FABRICATED BY FRICTION STIR PROCESSING

In low-strength metals, the main purpose of enhancing surface properties is to increase the abrasion resistance. One of the new methods for improving the microstructure of the surface layer of metals is the surface composite. In this research, the friction stir processing (FSP) was used to develop an aluminum–nickel intermetallic surface composite. Aluminum 2024 alloy and Ni powder were used as the matrix and reinforcement agent, respectively. Comparison of composite and non-composite FSP samples indicates that adding reinforcements improves the wear resistance of a monolithic metal in all condition. Also, the wear resistance of fabricated composites using activated Al–Ni powder is higher than the others due to the presence of Al3Ni2 and Al3Ni intermetallic compounds. At low traverse speed of the FSP, powder agglomeration occurs, and the powders are not uniformly distributed, as a result, the friction coefficient rises. SEM micrographs of scratched particles of activated composite confirm the delamination mechanism in the wear stable stage.

Zastosowanie technologii wybuchowego platerowania metali do wytwarzania nowych zaawansowanych materiałów warstwowych na przykładzie połączenia tytan Ti6Al4 – aluminium AA2519

Explosive metal cladding technology has been extensively developed since the mid-20th century. It is an area with the largest use of explosives for civil purposes, apart from mining. The global production of these materials runs at tens of thousands of square metres annually. Explosive bonding enables the production of a wide range of intermetallic compositions where, in many cases, no alternative methods are available. As an example, layered products include clad plates made of light metals, e.g. titanium, aluminium, magnesium showing different melting points, densities and hardness. Each new material combination requires an adaptation of the technology used by selecting suitable bonding parameters and new modified explosives. Several variants of Ti6Al4V/AA2519 explosive alloy bonding technology were created. The clad plates were tested using destructive and non-destructive techniques to determine bond strength and integrity. The study aimed to create new materials with improved ballistic resistance for structures used in the aviation and space industry.

Self-lubricating materials for extreme temperature tribo-applications

Abstract Growing demand in the materials working at extreme environmental conditions has raised a serious concern for lubricating mediums in the field of tribology. Limitations of conventional liquid based lubricants to decompose beyond 300 °C and its associated human health and environmental hazards have compelled to look for an alternative. Self-lubricating materials are new generation materials utilizing the benefits of incorporated solid-lubricating compounds to minimize friction and wear over a wide range of temperatures. This paper is an effort to summarize the existing solid-lubricating materials (polymer based, soft metal based, intermetallic composites, metal oxides and fluorides, TMDs, hBN based) for tribological applications under cryogenics (-269 °C) to high temperature (upto 1000 °C) environment. Their lubricating mechanisms and associated reason behind friction reduction is discussed. The paper also introduces the key characteristics of a futuristic ‘smart’ tribo-material.

A Study on Material Properties of Intermetallic Phases in a Multicomponent Hypereutectic Al-Si Alloy with the Use of Nanoindentation Testing.

The paper concerns modeling the microstructure of a hypereutectic aluminum-silicon alloy developed by the authors with the purpose of application for automobile cylinder liners showing high resistance to abrasive wear at least equal to that of cast-iron liners. With the use of the nanoindentation method, material properties of intermetallic phases and matrix in a hypereutectic Al-Si alloy containing Mn, Cu, Cr, Ni, V, Fe, and Mg as additives were examined. The scanning electron microscope equipped with an adapter for chemical composition microanalysis was used to determine the chemical composition of intermetallics and of the alloy matrix. Intermetallic phases, such as Al(Fe,Mn,M)Si, Al(Cr,V,M)Si, AlFeSi, AlFeNiM, AlCuNi, Al2Cu, and Mg2Si, including those supersaturated with various alloying elements (M), were identified based on results of X-ray diffraction (XRD) tests and microanalysis of chemical composition carried out with the use of X-ray energy dispersive spectroscopy (EDS). Shapes of the phases included regular, irregular, or elongated polygons. On the disclosed intermetallic phases, silicon precipitations, the matrix, values of the indentation hardness (HIT), and the indentation modulus (EIT) were determined by performing nanoindentation tests with the use of a Nanoindentation Tester NHT (CSM Instruments) equipped with a Berkovich B-L 32 diamond indenter. The adopted maximum load value was 20 mN.

Mechanical Properties of Mechanical Alloyed and Spark Plasma Sintered NiAl-Based Intermetallic Composites

The mechanical and microstructural properties of NiAl-based intermetallic composites reinforced with graphene nanoplates (GNPs) were investigated. Three different graphene contents, 0.5, 1 and 1.5 wt.%, were considered to investigate its effect on the nanocomposite properties produced by mechanical alloying and spark plasma sintering. The results showed that in the presence of graphene, the bending strength improved by almost 52.7% compared to the pure NiAl due to homogenous distribution of GNPs, the grain refinement and strength of the graphene. Among all the produced samples, NiAl-1 wt.% GNPs exhibit the highest mechanical and microstructural properties such as toughness (6.21 GPa√m), microhardness (6.71 GPa) and bending strength (83.88 ± 4 MPa). The perovskite phase (Ni3AlC0.5) was formed by increasing the graphene up to 1.5 wt.%, which reduced the mechanical properties compared to the other samples.

Formation of an intermetallic GdCo2 alloy on controlled annealing of a Gd/Co multilayer

One of the prospective routes for the formation of intermetallic composites is considered to be via annealing of heterostructures, which allows formation of alloys at a much lower temperature than the melting points of the individual elements. In this study, a binary alloy, GdCo2 was produced on the rapid annealing of a Gd/Co multilayer at 600 °C. Reflectivity measurements revealed that the entire Co layer intermixed with a large part of the Gd layer and formed a thick GdCo2 alloy layer with a magnetization of ~225 emu/cc at room temperature. It was achieved due to the high interdiffusion of elements across interfaces of the Gd/Co multilayer upon annealing.

Iron-rich intermetallics in high pressure die cast A383 aluminum alloys

This work describes the composition and crystal structure of Fe-rich intermetallics that form during the high pressure die casting (HPDC) process of alloy A383. Engine castings were produced using the HPDC process with A383 material with a nominal iron content of 1 wt %. Quantitative energy dispersive X-ray spectroscopy (EDS) was used to measure the chemical composition of Fe-rich intermetallics that formed during the process, and electron backscattered diffraction (EBSD) was used to identify their corresponding crystal structures and space groups. The results revealed that there were two types of Fe-rich intermetallics: sludge particles with a polygonal morphology and α-Fe with a Chinese-script shape. No needle-like β-Fe intermetallics were observed. Sludge and α-Fe had the same crystal structures, indexed as body-center cubic (bcc) with the same space group of Im3¯(No. 204). Sludge contained more Mn and Cr than α-Fe, whereas there was a larger concentration of Cu in α-Fe than sludge. ThermoCalc software was used to estimate the formation temperature of Fe-rich intermetallics, and the results suggested that α-Fe (Al8Fe2Si) with the bcc crystal structure and sludge were the same phase but formed at different temperatures during solidification process.

Effect of severe plastic deformation on evolution of intermetallic layer and mechanical properties of cold roll bonded Al-Steel bilayer sheets

In this study, evolution of intermetallic layer of the cold roll bonded bilayer of Aluminum-Steel sheets, during severe plastic deformation (SPD) followed by annealing has been investigated. The effect of such evolution on mechanical properties has been discussed. For this purpose, Constrained Groove Pressing (CGP) was used as a SPD process. Field emission scanning electron microscope equipped with energy dispersive spectroscopy and optical microscopy were used for examination of intermetallic compounds morphology and composition. Meanwhile, tensile properties of the bilayer sheets were evaluated. According to microstructural observations, continuous intermetallic layer was formed during rolling and annealing processes. This intermetallic layer was completely cracked into very fine particles after the first pass of CGP. Some of these intermetallic compounds were pushed into the base layers by the shear stress and some of them remained at the interface. Moreover, it was observed that during the CGP process, at the interface and between remaining intermetallic compounds and fresh surfaces of both Al and steel, new bonds were formed. After formation of such new bonds and during the second step of the CGP process, flattening process, mechanical interlocks were created. However, after the second CGP pass, no intermetallic compound was observed at the interface yet delamination was seen. Due to formation of intermetallic compounds at the bonding area and the vicinity of it, reinforced area, mechanical interlocks and higher dislocation density in that region, the ultimate tensile strength (UTS) increased after the first pass of CGP, but due to delamination, it decreased in second pass. The effect of evolution of bond structure on the tensile strength was measured by using bonding portion (BP) criterion defined as the difference in the UTS of the bonded versus non-bonded samples undergone similar deformation and annealing treatment. The BP values show similar trend to the UTS data, increased at the first pass and decreased at the second pass. In the following study, the CGPed samples have been annealed in order to recover the intermetallic layer. The CGPed samples were annealed at 350 °C, 400 °C and 450 °C for 30, 60 and 90 min. The optimum thickness of 2.6 μm was observed at the 450 °C in 30 min annealing treatment. The UTS, BP and elongation to break increased 7%, 32% and 60%, respectively, in comparison to those of the as-CGPed sample.

RESEARCH OF THE CORROSION RESISTANCE OF BIMETALLIC TRANSITION ADLEMENTS AD1 + ST3

The corrosion resistance of AD1 + St3 bimetal and a layered intermetallic composite of the same system was studied. It has been established that under the influence of an aggressive environment simulating the effect of a moist marine atmosphere, the presence of intermetallic inclusions and interlayers at the junction boundary helps to slow down corrosion processes.

Microstructure characteristics of a high-entropy-alloy intermetallic laminate composite

The multi-principal elements CoCrFeNi/aluminide high-entropy-alloy intermetallic laminate composites (HILC) was prepared by solid diffusion welding method. The results showed that three intermetallics layers formed between CoCrFeNi and Al sheets. The intermetallic phases in the layers were identified to be Al5(FeCoCrNi)2 multi-principal elements ordered solid solution, Al13(FeCoNiCr)4 ordered solid solution, and Al13(FeCoNi)4 ordered solid solution + Al13Cr2 intermetallics, respectively. The hardness of intermetallic layers was much higher than that of CoCrFeNi alloy, which obeyed the design concept of metal-intermetallic laminate composites (MILC). The research and development of HILC broadened the MILC family.