Complex Phase Composition Research Articles

Investigation on the mechanical and microstructure properties of masonry cement-red mud-carbide slag-based paste

The high alkalinity and complex phase composition of red mud pose significant challenges for its direct utilization. The construction industry is widely regarded as the most viable option for large-scale consumption of red mud to mitigate its continuous accumulation globally. Activation treatment is a crucial prerequisite for preparing cementitious materials from red mud, but traditional methods either require high-temperature calcination of red mud or the use of substantial amounts of strong alkaline substances as alkaline activators, thereby increasing costs and hindering the large-scale application of red mud. This paper presents an alternative method where 4% carbide slag is used as an activator to prepare cement-red mud-carbide slag-based composite pastes, substituting 10%-90% of masonry cement with red mud. As the red mud content increases, the compressive and flexural strengths of the hydrated pastes significantly decrease; the compressive strength of the material with 10% red mud is 13.4 times that of the material with 90% red mud. The addition of 4% carbide slag enhances the compressive and flexural strengths of the red mud-based cementitious material, with increases of 1.67%, 17.9%, and 34.6% in compressive strength at 3d, 7d, and 28d, respectively, and increases of 2.38%, 6.67%, and 7.36% in flexural strength. This indicates that carbide slag is beneficial for activating the reactivity of red mud. There is an incremental relationship between the flexural and compressive strengths of the cementitious material, and a fitting formula can be used to quantify the relationship between red mud content and these strengths. Microstructural analysis confirms that the addition of carbide slag significantly optimizes the pore structure, promoting the formation of Ca(OH)2 and C-S-H gel, which leads to improved mechanical properties of the red mud-containing composites. This study provides a feasible solution for the large-scale application of red mud in the cement industry.

High-temperature exposure of the high-strength 18Ni-300 maraging steel manufactured by laser powder bed fusion: oxidation, structure and mechanical changes

The present work describes the effect of long-term (8 weeks) high-temperature oxidation (500 °C) on the formation of an oxide layer as well as on the microstructure and mechanical properties of the 3D-printed 18Ni-300 maraging steel. For this purpose, samples produced by additive manufacturing in the as-built and the as-built + solution annealed and aging treated states were used. The as-built + solution annealed and aging treated material was found to be more prone to oxide layer formation due to a homogeneously distributed Ni3Mo intermetallic phase in the material matrix compared to the as-built material. The 8 weeks long exposure to a temperature of 500 °C has caused the formation of a thick oxide layer that exhibited a very bad adhesion with the metal matrix/oxide. The X-ray diffraction analysis confirmed the formation of a layer with a complex phase composition: martensite, austenite, Fe2O3, and Fe3O4. Moreover, the presence of CoFe2O4 was determined on the thin outer oxide layer using X-ray photoelectron spectroscopy. The phenomenon of over-aging was found to be the most significant after the first week of high-temperature oxidation. Then, a negligible change in the microhardness was observed throughout the entire experiment. X-ray diffraction analysis and energy dispersive spectroscopy confirmed the phase composition of the alloy corresponding to 75% of martensite + 25% of austenite as well as the change of Ni3Mo precipitate to Ni3(Mo, Ti) type after the long-term oxidation.

On the fatigue behavior of a tool steel manufactured by powder bed based additive manufacturing—a comparison between electron- and laserbeam processed AISI H13

In recent years, additive manufacturing (AM) techniques have gained increased attention. The most common AM technologies to realize complex parts are powder bed-based fusion processes, especially electron beam powder bed fusion of metals (PBF-EB/M) and laser-based powder bed fusion of metals (PBF-LB/M). Focusing on industrial applications, cyclic loading scenarios and fatigue properties of components produced by such techniques came into focus of research. The present work deals with a comparison between microstructure, hardness, density and fatigue properties of a high-alloy tool steel AISI H13 (1.2344, X40CrMoV5-1) manufactured by PBF-EB/M and PBF-LB/M. The investigated specimens are characterized by a complex phase composition containing ferrite, perlite, bainite and martensite, eventually resulting in different hardness values depending on the used AM technology. Fatigue data for PBF-EB/M AISI H13 are reported for the first time in open literature. It is shown that the fatigue behavior is significantly influenced by the specimen density. Accordingly, parts with a high density are characterized by superior fatigue strength.

The Remarkable Role of Indium in Synergistically Optimizing Carrier Concentration and Phase Distribution of AgCuTe-Based Materials.

Carrier regulation has proven to be an effective approach for optimizing the thermoelectric performance of materials. One common method to adjust the carrier concentration is through element doping. In the case of AgCuTe-based materials, it tends to form with cation vacancies, resulting in a high hole concentration and complex phase composition at low temperatures, which also hinders material stability. However, this also offers additional opportunities to manipulate the carrier concentration. In this study, the improved performance of AgCuTe through indium doping is reported, which leads to a reduction in hole concentration. In combination with a significant increase in the effective mass of the carriers, the enhanced Seebeck coefficient is also realized. Particularly, a notable improvement in power factor is observed in the hexagonal phase near room temperature. Furthermore, a lower electron thermal conductivity is achieved, contributing to an average figure of merit value of ≈1.21 (between 523 and 723K). Additionally, the presence of indium inhibits the formation of the second phase and ensures a homogeneous phase distribution, which reduces the instability arising from phase transition. This work significantly enhances the potential of AgCuTe-based materials for low to medium-temperature applications.

Microstructure, Phase Composition, and Mechanical Properties of Intermetallic Ni-Al-Cr Material Produced by Dual-Wire Electron-Beam Additive Manufacturing

Electron-beam additive manufacturing is one of the most promising methods for creating complex metal parts and structures. Additive manufacturing has already gained wide acceptance in the creation of various constructions from aluminum, copper, titanium, and their alloys as well as different classes of steels and other metallic materials. However, there are still many challenges associated with the additive manufacturing and post-production processing of intermetallic alloys. Thus, it is currently an urgent task for research. In this work, heat-resistant intermetallic alloys based on nickel, aluminum, and chromium were produced by dual-wire electron-beam additive manufacturing using commercial NiCr and Al wires. The microstructure, phase composition, and microhardness of the intermetallic billets are strongly dependent on the ratio of NiCr and Al wires, which have been fed during the additive growth of the material (NiCr:Al = 3:1 and NiCr:Al = 1:3). A metal-matrix composite material (Al3Ni-based intermetallide in Al-based matrix) was fabricated using the NiCr:Al = 1:3 ratio of the wires during the deposition. In tension, it fractures in a brittle manner before the plastic deformation starts, and it possesses a high microhardness of 6–10 GPa with a high dispersion of the value (the mean value is 8.7 GPa). This is associated with the complex phase composition of the material and the high fraction of a brittle Al3Ni intermetallic phase. In the material, obtained with the ratio NiCr:Al = 3:1, the ordered Ni3Al(Cr) and disordered Ni3Cr(Al) intermetallides are the dominating phases. Its microhardness turned out to be lower (4.1 GPa) than that in Al + Al3Ni-based composite, but intermetallic Ni3Al-based alloy demonstrates good mechanical properties in a high-temperature deformation regime (650 MPa, more than 10% elongation at 873 K). Microstructural studies, analysis of phase composition, and tensile mechanical properties of additively produced intermetallic materials show the perspective of dual-wire electron-beam additive manufacturing for producing intermetallic compounds for high-temperature applications.

Spectromicroscopy Studies of Silicon Nanowires Array Covered by Tin Oxide Layers.

The composition and atomic and electronic structure of a silicon nanowire (SiNW) array coated with tin oxide are studied at the spectromicroscopic level. SiNWs are covered from top to down with a wide bandgap tin oxide layer using a metal-organic chemical vapor deposition technique. Results obtained via scanning electron microscopy and X-ray diffraction showed that tin-oxide nanocrystals, 20nm in size, form a continuous and highly developed surface with a complex phase composition responsible for the observed electronic structure transformation. The "one spot" combination, containing a chemically sensitive morphology and spectroscopic data, is examined via photoemission electron microscopy in the X-ray absorption near-edge structure spectroscopy (XANES) mode. The observed spectromicroscopy results showed that the entire SiNW surface is covered with a tin(IV) oxide layer and traces of tin(II) oxide and metallic tin phases. The deviation from stoichiometric SnO2 leads to the formation of the density of states sub-band in the atop tin oxide layer bandgap close to the bottom of the SnO2 conduction band. These observations open up the possibility of the precise surface electronic structures estimation using photo-electron microscopy in XANES mode.

An innovation technology for recovering silver and valuable metals from hazardous zinc leaching residue through direct reduction

Zinc leaching residue (ZLR) is a hazardous solid waste with complex phase composition, comprising high content of valuable metals, and sulfur. The extraction of silver is the key to harmless utilization of ZLR. In this paper, a short-flowsheet comprehensive recycling valuable metals method by direct reduction was proposed. During reduction, lead and zinc compounds were reduced to metallic state, which were volatilized and recovered in gas phase. Moreover, metallic iron in reduction product was recovered by magnetic separation. Silver was enriched in FeS phase, and it was beneficiated by flotation with hydrophobic FeS as carrier. Under the optimized conditions, silver concentrate with silver content and recovery of 601.43 g/t and 83.41 %, respectively; iron powder with iron content of 96.39 %; and lead and zinc volatilization rate of 78.65 % and 97.64 %, respectively, were obtained. Toxicity characteristic leaching procedure (TCLP) results indicated that tailings were harmless. The mechanisms were subsequently investigated by combining thermodynamics analyses and systematic characterizations. Especially, a one-step containing two-stage capture silver mechanism was ascertained in reduction with sulfur: formation of silver-lead alloys, and encapsulation of silver-lead alloys by FeS phase to decrease symbiotic relationship between valuable metals and slag. This entire recycling process can provide ideas for harmless recovering precious metals from hazardous waste.

STUDY OF LOW-TEMPERATURE OXIDATION OF CARBON MONOOXIDE ON Cu–Mn–Fe CATALYTIC OXIDE SYSTEMS OBTAINED BY THE SOL-GEL COMBUSTION METHOD

The oxidation of carbon monoxide was studied on oxide Cu–Mn–Fe catalytic systems with metal ratio Cu:Mn:Fe=1:1:1; 2:1:1; 1:2:1 and 1:1:2 obtained by the sol-gel method with combustion. The results of X-ray phase analysis showed that the catalytic systems have a complex phase composition. Along with double oxides of manganese and iron, ferrites of copper-, manganese, copper manganite, manganese-substituted copper ferrites were formed (CuFe2O4; Mn0.43Fe2.57O4, Mn0.98Fe2.02O4; CuMn2O4; Cu1.2Mn1.8O4; Cu0.5Mn0.5Fe2O4). It has been found that depending on the ratio of metals in the catalyst, the reaction start temperature is in the temperature range of 120–1700C. And after 3–5 minutes after the start of the reaction, the conversion begins to increase sharply, reaching 100% within the next 5 minutes

Structure and phase composition of electrically conductive carbon black

A comprehensive study of the structure and phase composition of a promising brand of electrically conductive carbon black was carried out. It is shown that the material under study has a complex phase composition, which, along with carbon, includes other elements and compounds, such as sulphur, oxygen, nitrogen, and vanadium oxides. The structural state of carbon black can be defined as amorphous. The presence of functional oxygen-containing groups in the material, presumably attached to the edge carbon atoms of graphene layers, has been proved. The interrelation of some characteristics of the structure and phase composition of the material and the properties of polymer composites is discussed.

Digital light processing porous TPMS structural HA & akermanite bioceramics with optimized performance for cancellous bone repair

In recent years, amorphous bioglass is used to improve the bioactivity of HA (Ca 10 (PO 4 ) 6 (OH) 2 ). Nevertheless, bioglass crystallizes and reacts with the matrix to form a complex phase composition during sintering, resulting in an unclear mechanism for tailoring the properties of HA bioceramics. In this work, TPMS structural HA ceramics fabricated by digital light processing (DLP) were doped by akermanite (Ca 2 MgSi 2 O 7 ) to better tailor the porosity, bioactivity and mechanical strength. After sintering above 1000 °C, Mg 2+ ions from akermanite substitute Ca 2+ ions in HA, leading to the decomposition of HA into β-TCP. This process increases the porosity of bioceramics. Additionally, liquid phases sintering caused by akermanite gives rise to the densification and enhancement of grain bonding, thereby reinforcing the mechanical strength of scaffolds. For in vitro bioactivity, as the content of akermanite increases from 0 wt% to 20 wt%, carbonated hydroxyapatite firstly deposits onto the surfaces of scaffolds and then disappears, because excessive Mg 2+ prevent the hydroxyapatite crystallization. Finally, bioceramics with 5 wt% and 10 wt% of akermanite and sintering at 1100 °C exhibit a high porosity of over 80% and an appropriate compressive strength of over 2 MPa, while achieving an enhanced in vitro bioactivity and good biocompatibility. After optimization, this kind of porous scaffolds can be well applied to the repair of cancellous bone defect.

Current Status of Carbidic Austempered Ductile Iron

Grinding balls in wet ball mill are important consumables in mine grinding equipment, which have poor wear resistance and large consumption. It is imperative to find excellent wear-resistant materials for the grinding balls. Carbidic Austempered Ductile Iron (referred to as CADI) was used as small and medium-sized wet ball mills. This grinding ball has the advantages of less wear, low crushing rate, power saving and low noise. However, the CADI grain boundaries are distributed with net-like eutectic carbides, which seriously damage the continuity of the matrix. In addition, the mechanism of corrosion wear and impact fatigue is lack of research due to complex phase composition and unclear mechanism of phase properties on improving performance. So CADI can’t be applied to the grinding balls in large wet ball mill. Based on the above problems, this paper first analyzed the heteronucleation mechanism and adsorption mechanism of M3C type carbides by using the first principle of microalloying elements, and then verified it by combining with experimental results. Then the thermodynamics and kinetics of austenite homogenization and isothermal transformation of ductile iron containing carbides were analyzed by means of modeling calculation and experiment. On this basis, a new type heat treatment process comprising super-high temperature pretreatment and austempering treatment (S&A treatment) was used to process CADI, which provides a new idea for further improving toughness of CADI. Finally, the CADI corrosion wear and impact fatigue failure mechanism were revealed by analyzing the change rule of the sample surface and cross section after corrosion wear and impact fatigue.

Термическое разложение химически осажденного нанопорошка гидроксида алюминия

In this study, the phase formation of aluminum oxide nanopowder during thermal heating of chemically precipitated aluminum hydroxide was discussed. Nanopowders of aluminum oxide and hydroxide were characterized by X-ray diffraction and thermogravimetric analysis, electron microscopy, energy dispersive X-ray spectroscopy analysis. XRD analysis detected a complex phase composition consisting of different modifications of aluminum hydroxide. It was shown that the precipitated aluminum hydroxide has a flake morphology with an average particle diameter of 5.5 nm. The differential thermal analysis showed that as-deposited aluminum hydroxide undergoes a multiple stage phase transformation. The deconvolution of the experimental differential curve by the Gaussian function and comparison of the temperature intervals of mass change with the literature data revealed that the precipitated aluminum hydroxide powder consists of bayerite α-Al(OH)3 and aluminum oxyhydroxide AlOH. It was found that bayerite is transformed to boehmite in the temperature range of 100 – 400 °C. After that γ-Аl2O3 is formed during the thermal decomposition of boehmite in the temperature range of 400 – 530 °C. The second hydroxide phase formed during the chemically precipitated method has a single stage phase transformation from AlO(OH) to γ-Аl2O3 in the temperature range of 260 – 500 °C. The nanopowder of γ-Аl2O3 formed at the temperature of higher than 600 °C has an equiaxed particle shape and an average size of 7 nm.

STUDY OF PHASE TRANSFORMATIONS IN FERROELECTRICS BASED ON CALCIUM TITANATE.

The aim of this work is to study phase transformations kinetics in ferroelectrics based on calcium titanate. The relevance of this study is in the assessment of new methods for obtaining complex phase composition ferroelectrics, which have the potential for application in microelectronics, photocatalysis, and power engineering. The methods of scanning electron microscopy and X-ray diffraction were used as the main methods of analysis. Analysis of morphological features made it possible to establish the kinetics of changes not only in grain sizes, but also in their geometry. During the studies of phase transformations, the following dependence of the TiO2 – anatase/CaTi2O4 → TiO2– anatase /CaTi2O4/CaTiO3 → CaTiO3/TiO2 – rutile type was established depending on the annealing temperature. At the same time, at a temperature of 1000°C, a stable structure of ceramic with a perovskite-like structure of the CaTiO3 type and a high structural ordering degree (more than 92%) is formed.

A new approach to recover the valuable elements in black aluminum dross

Black aluminum dross (BAD) is a solid hazardous waste produced during the remelting of aluminum alloy scrap and contains a large amount of aluminum and other valuable elements. However, the extraction of its high-value components is challenging because of its complex phase and chemical composition. In this paper, a new process for recovering aluminum and other valuable elements from BAD is reported, which consists of three steps, i.e., catalytic hydrolysis of aluminum nitride, calcination of the obtained aluminum hydroxide, and molten salt electrolysis to prepare aluminum alloy. Under the established optimal conditions for the hydrolysis of aluminum nitride, 4 wt% NaOH, a temperature of 90°C, a liquid-solid ratio of 6 mL g−1, and a reaction time of 3 hours, the recovery rates of nitrogen and chloride salts are 88.8% and 97.57%, respectively. Bayerite and pseudo-boehmite generated by the hydrolysis of aluminum nitride present in BAD were converted into γ-Al2O3 when calcining the material at 800°C for 2 hours resulting in a multi-metal oxide with high alumina content. Aluminum alloy was prepared by electrolysis of the material in the Na3AlF6-AlF3-Al2O3 electrolyte system. This innovative technology can recover 97% of aluminum and other valuable metals (including silicon) in BAD and is a new route to achieve clean and high-value recycling of BAD.

Effect of chemical composition and T6 heat treatment on the mechanical properties and fracture behaviour of Al-Si alloys for IC engine components

The microstructural examinations of Al-Si alloys intended to manufacture IC engine components revealed a complex phase composition in all the samples. The polyhedral crystals of primary silicon were detected in the Al-12.5Si alloy, besides the ?-Al phase, eutectic silicon, and several intermetallic phases, identified in the cast samples of both alloys. Better tensile properties were found for the samples of Al-11Si. A predominantly intercrystalline fracture with features of ductile failure was observed in both alloys. In as-cast specimens of the Al-11Si alloy, the cracks were formed by the decohesion mechanism between the particles of the intermetallic phase AlCuFeNi and the ?-Al phase. The microcracks initiated on the interface were spread along the branches of the ?-Al15(Fe,Mn,Cu)3Si2 particles. After T6 treatment of the Al-11Si alloy, almost half of the intermetallics quantity presented the Al3Ni phase, while the iron-based phases were observed in a small amount. Spheroidized eutectic silicon, a smaller portion of Al5Cu2Mg8Si6, and a more considerable quantity of Al3(Fe,Mn,Cu,Ni,Co) were detected for T6 specimens of the Al-12.5Si alloy. The rounded crystals of eutectic silicon contributed to the improvement of their tensile properties. Larger and deeper dimples of mostly polygonal shapes were observed in the samples of the Al-11Si alloy after T6 treatment. The microcracks occurred at the boundary of the intermetallic phase/?-Al solid solution.

Microstructure and Phase Evolution Mechanism in Hot-pressed and Hot-deformed Nd-Fe-B Magnets with Nd85Cu15 Addition

Chemical composition and structure characteristics of the intergranular phases in Nd-Fe-B magnets play a key role in regulating the magnetic properties. However, it has still been a challenge to understand the evolution mechanism of grain boundary phases in hot-pressed and hot-deformed Nd-Fe-B magnets due to the complex phase composition and structure. In this work, grain boundary modification using Nd85Cu15 alloy has been applied to hot-pressed and hot-deformed Nd-Fe-B magnets. The structure evolution mechanism of the grain boundary phase during hot-pressing was studied by TEM analysis, which shows that an overall reaction, Nd + Nd26Ga7Co10 + Nd2Fe14B → Nd3Co + Nd5Fe2B6 + Nd6(Fe,Co)13Ga, occurs at 600°C in hot-pressed magnet with Nd85Cu15 addition. When the hot-deformation was conducted at 675°C abnormal grain growth was observed in hot-deformed magnets with or without Nd85Cu15 addition. In contrast, as the hot deformation temperature decreased to 630 °C, the uniform and ultra-fine Nd2Fe14B grains formed in the Nd85Cu15 doped magnet, which shows a significantly improved coercivity of 2.03 T and a squareness factor of 0.93.

Electrochemical synthesis, structure characterization and magnetic properties of TbxFe7Co3 (x=0, 0.6, 0.8) nanowires

Highly ordered TbxFe7Co3 (x = 0, 0.6, 0.8) nanowires were synthesized in alumina templates by electrochemical deposition method. Here, the effects of Tb content and annealing treatment on the phase composition, morphology, crystalline structure and magnetic properties were investigated. The as-deposited Tb0Fe7Co3 nanowires comprise Fe7Co3 phase. While after adding Tb, the diffraction peaks slightly shift left, indicating the infiltration of Tb atoms into Fe7Co3 phase. After annealing, Tb0Fe7Co3 nanowires still consist of Fe7Co3 phase with a slight enhancement on coercivity. While the annealed nanowires with Tb doped present a complex phase composition containing Fe3Tb, Fe2Tb, Co3Tb, Co17Tb2, TbFeO3 and Fe2O3 phases distribute in the central portion, and Co0.72Fe0.28 at the nanowire outer walls. The annealed TbxFe7Co3 (x = 0.6, 0.8) nanowires show higher magnetic performance owing to the formation of hard magnetic phases, the interfacial elastic coupling between hard and soft phases and the coherent Fe3Tb/Co3Tb interface which restrain the domain wall motion. To be specific, the coercivity and remanence ratio of TbxFe7Co3 (x = 0.6, 0.8) nanowires significantly enhance with increasing Tb content.

Polymer‐derived Co2Si@SiC/C/SiOC/SiO2/Co3O4 nanoparticles: Microstructural evolution and enhanced EM absorbing properties

AbstractIn this work, porous core‐shell structured Co2Si@SiC/C/SiOC/SiO2/Co3O4 nanoparticles were fabricated by a polymer‐derived ceramic approach. The in situ formation of mesopores on the shell, microstructural, and phase evolution of resulting nanoparticles were investigated in detail. The obtained nanoparticles‐paraffin composites possess a very low minimum reflection coefficient (RCmin) −60.9 dB, broad effective absorption bandwidth 3.50 GHz in the X‐band and 15.5 GHz in the whole frequency range (from 2.5 to 18 GHz). The results indicate outstanding electromagnetic wave (EMW) absorbing performance among all the reported cobalt‐based nanomaterials, due to the reasons as follows: (a) The unique core‐shell structure as well as complex phase composition of SiC/C/SiOC/SiO2/Co3O4 in the shell, result in a large number of heterogeneous interfaces in the nanoparticles; (b) Nanoparticles have both dielectric and magnetic loss; (c) Mesopores in the shell prolong the propagation path of EMW, thereby increasing the absorption/reflection ratio of EMWs. Thanks to the material structure design, the resulting core‐shell structured cobalt‐containing ceramic nanoparticles have great potential for thin and high‐performance EMW absorbing materials applied in harsh environment.

Structural-Phase State of the Interphase Boundary at Thermal Diffusion Metallization of Diamond Grains by Fe, Ni and Co

Structural-phase state of the diamond-metallized coating interphase boundary after thermal diffusion metallization of diamond grains by transition metals Fe, Ni and Co were studied. Metallization were conducted under temperature-time mode corresponding to the sintering of cemented carbide matrices with Cu impregnation. The structural-phase state of the metallized coating and diamond-coating interphase boundary was studied by scanning electron microscopy, X-ray phase analysis and Raman spectroscopy. A metallized coating strongly adhered to the diamond forms during thermal diffusion metallization of diamond by iron. The metallized coating has a complex structural phase composition of iron, a solid solution of carbon in iron and graphite phases. Nickel and cobalt cause intense catalytic graphitization of diamond with the formation of numerous traces of erosion on its surface under the heating conditions specified in the experiment. The observed weak adhesive interaction of these metals with diamond is probably due to the high melting temperatures of the Ni-C and Co-C eutectics, which does not allow the metals to react with diamond under given experimental conditions.

Optimization of the heat treatment of additively manufactured Ni-base superalloy IN718

Additive manufacturing (AM) of Ni-base superalloy components can lead to a significant reduction of weight in aerospace applications. AM of IN718 by selective laser melting results in a very fine dendritic microstructure with a high dislocation density due to the fast solidification process. The complex phase composition of this alloy, with three different types of precipitates and high residual stresses, necessitates adjustment of the conventional heat treatment for AM parts. To find an optimized heat treatment, the microstructures and mechanical properties of differently solution heat-treated samples were investigated by transmission and scanning electron microscopy, including electron backs-catter diffraction, and compression tests. After a solution heat treatment (SHT), the Nb-rich Laves phase dissolves and the dislocation density is reduced, which eliminates the dendritic substructure. SHT at 930 or 954°C leads to the precipitation of the δ-phase, which reduces the volume fraction of the strengthening γ′- and γ″-phases formed during the subsequent two stage aging treatment. With a higher SHT temperature of 1000°C, where no δ-phase is precipitated, higher γ′ and γ″ volume fractions are achieved, which results in the optimum strength of all of the solution heat treated conditions.