β-NiAl Phase Research Articles

Effect of laser remelting on the microstructures and properties of NiCoCrAlY-based coatings prepared by high-speed air fuel supersonic flame (HVAF)

In order to improve the oxidation resistance of the coating, laser remelting technology was used to remelt the HVAF multi-component modified coating. The influence of laser remelting technology on the phase state, microstructure characteristics, and isothermal oxidation behavior of coatings was studied. The experimental results indicate that a coating with complete morphology and no defects was obtained on the surface. There is a significant amount of metallurgical bonding and partial mechanical interlocking between the remelted layer and the substrate. The remelted layer is mainly composed of β-NiAl phase, accompanied by a small amount of γ′ phase and oxide phase. The microhardness test results show that the average hardness of the remelted layer is 1.1–1.42 times that of the prepared coating, and the bonding strength has increased by 23 %. After 100 h of high-temperature oxidation, the oxidation rate of the 4N3T4H remelted layer is the lowest, at 1.5 × 10−15 cm2/s, which is one order of magnitude lower than that of the as-sprayed coating. This is because after laser remelting, the remelted layer has the inherent hysteresis diffusion effect of HEA, which can improve the high-temperature oxidation resistance of the remelted layer and basically eliminate many pores and cracks contained in the HVAF coating. The coating density is significantly increased, which is conducive to hindering the diffusion of oxygen. Meanwhile, the oxide of HVAF coating mainly accumulates at pores and cracks, and there is no or late formation of uniform and dense oxide film on the surface. The surface of the remelted coating after oxidation forms a relatively uniform and dense oxide film, providing more effective protection for the substrate.

Effect of Ta on selective oxidation behavior and oxide film adhesion of alumina-forming austenitic alloys

The effects of Ta on the selective oxidation behavior and scale adhesion of Fe-45Ni-25Cr-4Al-1.5Nb-0.4C-xTa (x=0.6, 0.9, 1.2, 1.5 wt%) austenitic alloys at high temperature under low oxygen pressure were investigated. The FCC, MC-(Ta, Nb)C, M23C6 and B2-NiAl phases were found in the annealed alloy. Addition of Ta significantly promoted the formation of an external Al2O3 layer and inhibited growth of Cr2O3 and spinel at 850 °C under oxygen pressures of 10−18 atm and 10−24 atm. Similar oxidation behavior was observed in two-step oxidation process (650 °C for 8 hours and 1000 °C for 16 hours). Ta and Nb preferentially segregated at the interface between the oxide scale-matrix as well as grain boundary within the oxide scale during oxidation, and inhibited outward diffusion of Al and Cr. A large oxygen activity gradient was formed in the oxide film, resulting in the formation of columnar grains. Due to a significant decrease in oxygen activity at the front of the reaction, selective oxidation of alumina was promoted. Furthermore, the scratch test technique was used to quantify the adhesion of oxide scales. Peg-like structures formed by Ta and Nb positively influenced the adhesion properties of the oxide scale.

Preparation and high temperature oxidation resistance of AlSiY coating by arc ion plating

AlSiY coating with excellent antioxidant property was deposited using the arc ion plating technique on a nickel-base single crystal superalloy René N5. The microstructures and morphologies of the coatings, the elemental content and composition of the phases were analyzed by scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS), and X-ray diffractometer (XRD). The results showed that the AlSiY coating was primarily comprised with β-NiAl phase with well combined with the substrate after heat treatment. The average oxidation rate of the coating for 300 h oxidation at 1050 ℃ was 0.8570 mg/cm2, superior to that of the substrate with 1.0035 mg/cm2. The coating exhibited good resistance oxidation during 1050 ℃, and the main phase was β-NiAl phase with high Al content after 300 h oxidation, which suggested that the coating could form a dense Al2O3 layer. In the 1100 ℃ oxidation process, although the depleted aluminum zone of γ′-Ni3Al was formed under the oxide layer after 300 h oxidation, the coating still had a high Al content, which could generate a continuous oxide layer on the surface of coating. The average oxidation rate of coating and substrate was 1.4070 mg/cm2, 3.2730 mg/cm2, respectively, which could provide good oxidation resistance for substrate. The investigation could provide some guidance for the preparation and industrial production of aluminide coatings.

Avoiding microstructural instabilities in high tungsten containing superalloys by adjusting Al content

The effects of Al contents on the microstructures and mechanical properties of superalloy with high tungsten content were studied. During solidification, Al was found to be enriched in the residual liquid, which led to the transformation of eutectic morphology from reticular to bulk-like. When the Al content increased to 8 wt%, β-NiAl phase formed in the inter-dendritic region, Thermo-Calc calculations confirms such the experimental phenomenon. The absolute value of the lattice misfit between the γ/γ' phases and the elastic strain energy increases, then the size of the γ' phase increases when the Al concentration rises from 7 wt% to 8 wt%. When the Al content increased to 7 wt%, the tungsten-rich α-W phase is precipitated and the volume fraction is 1.20%. The volume fraction of the α-W phase increases to 7.84% when the Al content reached 8 wt%, which is consistent with the Thermo-Calc calculation results. After the room temperature tensile and stress rupture life test at 975 °C / 235 MPa, it revealed that the precipitation of hard and brittle α-W and β-NiAl phases with high Al content, which resulted in the mechanical properties decreased due to the crack initiation at multiple locations and then interconnected. The higher density of γ' phase with 6 wt% Al makes it difficult for dislocations to bypass. The site of crack initiation is decreased due to the absense of brittle phase. The stress rupture life can reach 49.21 h of the alloy.

Effects of aluminizing on the microstructure and wear resistance of AISI 321 steel

To enhance the surface properties, particularly hardness and wear resistance, of AISI 321 steel, an aluminizing coating was introduced through pack cementation treatment. Microstructure characterization and wear resistance tests were conducted to elucidate the intricate relationship between the microstructure and wear behaviors. A thorough analysis on the structure and compositions revealed the incorporation of FeAl(Cr) phases, aluminum oxides, titanium compounds and B2-NiAl phases in the coating, which resulted in a remarkable 192 % increase on the surface hardness, elevating it from 226 HV to an impressive 662 HV. In comparison to the uncoated 321 steel, the aluminized counterpart exhibited a pronounced reduction in coefficients of friction (COFs), wear volume losses, and wear rates. The wear mechanisms of both the uncoated 321 steel and aluminized steel were intricately analyzed. The uncoated 321 steel endured severe adhesive and oxidation wear, characterized by pronounced plastic deformation, the presence of wear debris and flaking oxides. In contrast, the aluminized steel predominantly underwent abrasive wear, showcasing a relatively smooth worn surface and dense continuous oxides. These findings not only reveal the significant enhancement of tribological properties by aluminized coatings, but also provide valuable insights into their fundamental behavior during wear.

Investigation of the formation mechanism between β-NiAl and C14-Laves phases in laser additive manufacturing of nickel-based superalloy

The microstructure of laser additively manufactured nickel-based superalloy was analyzed using multi-scale characterization. The phase composition of the as-deposited sample was determined. The formation mechanisms of β-NiAl and C14-Laves phases were studied in depth. The crystallographic orientation relationship between the β-NiAl and C14-Laves phases was elucidated. The formation of the β-NiAl phase exacerbates the elemental segregation at the interface, leading to the generation of micro-strain and dislocations that provide nucleation sites for the C14-Laves phase. In addition, the effect of solidification rate on the precipitation of precipitated phases from the alloy was excluded. The present work contributes to understanding the precipitation behavior of β-NiAl and C14-Laves phases in nickel-based superalloys.

Deposition of a low-activity type cobalt-modified aluminide coating by slurry aluminizing of a pre-Co-electroplated Ni-based superalloy (IN738LC)

Incorporating the Co element into the β-NiAl phase as a third element enhances the hot corrosion and oxidation properties of aluminide coatings. The deposition of Co-modified aluminide coatings is limited to co-deposition by the pack cementation method or a two-step pack cementation process of Co and Al, so far. This study investigates the possibility of depositing a low-activity type of Co-modified aluminide coating by combining the electroplating process with the slurry aluminizing method. To accomplish this objective, different thicknesses of Co-electroplated layers, deposited by a Watts bath, ranging from 5 to 20 μm are slurry aluminized using a slurry consisting of Al particles as the Al source and a PVA aqueous solution as the binder at 1100 °C for 2 h. Formation mechanisms are discussed through slurry aluminizing of 5, 10, and 20 μm thick Co-electroplated layers at the temperature range of 700–1100 °C with 100 °C intervals at zero time. FE-SEM surface morphology, BSE-SEM cross-sectional observation, surface XRD characterization, and EDS elemental analysis are utilized to characterize the coatings. Results show a critical thickness of the Co layer is required to deposit a defect-free low-activity type of Co-modified aluminide coating, which is determined to be ∼10 μm in this study. The final aluminide coating thickness decreases from ∼140 to ∼65 μm by increasing the Co-electroplated layer thickness from 5 to 20 μm. The identified phases on the surface differ from β-NiAl to β-CoAl by increasing the Co-electroplated layer thickness up to critical value. The Void formation occurs by the Kirkendall effect in coatings with more Co-electroplated layer thickness than the critical value, segregating the coatings within the β-CoAl phase.

Effect of coatings on oxidation behavior of a fourth generation Ni-based single crystal superalloys at ultra high temperature

PtAl and MCrAlY coating were prepared on the fourth generation single crystal superalloy. The isothermal oxidation tests of superalloys with different coatings were performed at 1150 °C and 1200 °C in a muffle furnace with static air for 500 h. The isothermal oxidation behavior and mechanism of two coatings at 1150 °C and 1200 °C was investigated. MCrAlY coating improved oxidation resistance by forming adhesive oxide scales with pegs, and PtAl coating formed dense and coherent oxide scales on surface to hinder the diffusion of oxygen. Compared with two coatings, a smaller oxidize increasing weight of PtAl coating (0.54 mg/cm2) than MCrAlY coating (2.48 mg/cm2) indicated that PtAl coating presented a better oxidation resistance during oxidation test at ultra high temperature, although a significant interdiffusion behavior occurred between PtAl coating and substrate. Besides, the interactive behavior between Ru and coatings was also investigated. Ru in fourth generation single crystal superalloy could diffuse into β-NiAl phase of coatings, maintaining the integrity of coatings. The major difference between MCrAlY coating and PtAl coating came in the amounts of β-NiAl phase, which leading to the difference on the oxidation resistance between MCrAlY and PtAl. The mechanism about influence of temperature on the oxidation property on bare alloy, MCrAlY-DD91 and PtAl-DD91 was also discussed. Ultra high temperature would promote more elements to participate in the reaction with oxygen, change the compositions of oxide scale and phases, resulting to the spallation of oxide scale and decrease of oxidation resistance.

Oxidation and hot corrosion behaviors of NiAlTa protective material for turbine single crystal blade tips

NiAlTa alloys were prepared to improve oxidation and hot corrosion resistance of single crystal blade tips as well as the sealing performance of an engine. The oxidation and hot corrosion behaviors of NiAlTa alloys were investigated. The results showed that NiAlTa alloys exhibited low oxidative degradation rates at 1000–1100 ℃. τ1-NiTaAl and β-NiAl phases exhibited different oxidation behaviors. NiAlTa alloys were more resistant to attack by mixed salts than pure salts. NiTaAl phase accelerated the alloy failure by acting as a fast diffusion channel for corrosive media. The oxidation mechanisms, hot corrosion mechanisms, and the effects of Ta were discussed.

Precipitation of β-NiAl phase in a high Ru-containing Ni-based single crystal superalloy

The precipitation of β-NiAl phase in a high Ru-containing Ni-based single crystal superalloys was investigated. The β-NiAl phase is mainly distributed in the interdendritic region of the as-cast structure. And it was found parts of Ru elements were polarized in β-NiAl phase as the existence of strong bonds between Ru atoms and Al atoms. In addition, the solidification path of the experimental alloy passes through the region of the L → L1 + γ → L2 + γ + β-NiAl → L3 + γ + β-NiAl + precipitated γ′ → γ + β-NiAl + precipitated γ′ + γ/γ′ eutectics. It provides experimental data and theoretical guidance for the composition design of the novel Ru-containing high-generation Ni-SCs.

Variety of yield strength caused by precipitations of L12-Ni3Al and B2-NiAl phases in alumina-forming austenitic steel

Alumina-forming austenitic (AFA) steel exhibits excellent high-temperature properties and has attracted significant attention in thermal power generation industry. Microstructure evolutions and yield strengths of 20Ni-AFA steel during isothermal aging are investigated. The results show that five types of phases are found in 20Ni-AFA steel during isothermal ageing: NbC, L12-Ni3Al, M23C6, B2-NiAl and Laves phases. Addition of Cu causes precipitation of L12-Ni3Al phase in 20Ni-AFA steel at the early stage of isothermal aging. L12-Ni3Al phase grows and gradually transforms into B2-NiAl phase which possesses a more stable structure with the extension in isothermal aging time. The transformation leads to yield strengths of 20Ni-AFA steel to decrease anomalously during 24-120 h isothermal aging. Yield strengths of 20Ni-AFA steel increase again as isothermal aging time continues to increase.

Diffusion-controlled growth and microstructural evolution between Pt and Pd containing B2-NiAl bondcoats and Ni-based single crystal superalloy

Pt-modified NiAl bond coats are used to extend the lifetime of blades in gas turbine engine applications. However, they suffer from the growth of deleterious precipitates within the interdiffusion zone. Partial substitution of Pt by Pd is advantageous in reducing the interdiffusion zone thickness between the bond coat and the superalloy, providing comparable oxidation properties, and critically reducing the propensity to form brittle (Pt,Ni)Al2 precipitates. In this study, we utilize the pseudo-binary diffusion couple method to estimate the interdiffusion coefficients of Ni and Al in Pd, Pd-Pt and Pt-modified nickel aluminides. Additionally, the main and cross-interdiffusion coefficients are estimated in the ternary diffusion couples. The estimated diffusion coefficients in the β-NiAl phase reflect on the thickness of the β phase in the superalloy bond coat interdiffusion zone. Pd reduces the pseudo-binary interdiffusion coefficients of Ni–Al and also decreases the main and cross-ternary interdiffusion coefficients. This correlates with the reduction of the interdiffusion zone thickness by Pd. The diffusion process is strongly assisted by point defects in this phase. Ab initio-informed defect calculations are done to explain diffusion retardation in the presence of Pd (compared to Pt) with decreased defect concentrations. Furthermore, through in-depth microstructure characterization performed by electron probe micro analyser, transmission electron microscopy, and atom probe tomography, the presence of σ, R and μ phases as TCP precipitates in the interdiffusion zone are identified. The results give insights into the coatings’ diffusional properties that influence the service life of the product.

Cyclic oxidation-induced deleterious effects of Ru on the surface rumpling of a Pt-modified aluminide coating

Generally, surface rumpling is detrimental to high temperature protective coatings as it leads to adhesion losses and Ru can suppress rumpling behaviour in most Pt-modified aluminide (Pt-Al) coatings during the cyclic oxidation. However, in this study, we found that this suppression is related to the cyclic oxidation cycles of Pt-Al-coated superalloys: Ru suppresses rumpling behaviour with cyclic oxidation for more than 200 cycles at 1100 °C but aggravates it with cyclic oxidation from 50 to 150 cycles. The aggravation of rumpling behaviour was turned out to be associated with coating oxidation. Microstructure observation indicated that Ru participates in oxidation and deteriorates the oxidation resistance via destroying the integrity of the Al2O3 oxide film. More Al atoms are depleted owing to oxidation degradation, attributing to partial β-NiAl phases transformation towards the L10 martensitic phases, which exacerbates volume shrinkage and the driving force of rumpling behaviour. The Ru diffusion process during cyclic oxidation has also been studied. Furthermore, the relationship among martensite transformation, rumpling behaviour and cyclic oxidation in Pt-Al coated Ru-containing superalloy was ascertained to provide a guideline for integrated design of Pt-Al coating/high-generation SX superalloys and propose an investigation strategy for rumpling behaviour of the Pt-Al coating.

Transforming microstructures and mechanical properties of (CoCrNi)93-xAl7Ndx medium entropy alloy films by annealing

In this context, we aim to investigate the effects of Nd content and annealing on the microstructures and mechanical properties of a series of (CoCrNi)93-xAl7Ndx (x = 0, 0.22, 0.56, 1.05, 1.73, 2.55, 3.53) medium entropy alloy films. The results showed that doping with Nd resulted in grain refinement and triggered a transition from a single FCC solid solution to nanocrystalline and amorphous structures. The mechanical properties, evaluated using nanoindentation and micropillar compression tests, showed that 0.56 at.% Nd doping yielded the optimum outcome due to the formation of a solid solution and grain refinement. However, the mechanical properties dropped sharply with further increases in Nd content due to the inverse Hall-Petch effect and the transition from an FCC to an amorphous matrix. The annealing treatment (550 °C for 10 min) was found to enhance atomic diffusion and migration, facilitating lattice rearrangement and the formation of a large number of precipitates, including BCC Cr-rich, B2 NiAl, L12 Ni3Al, and HCP NdNi5 phases. In addition, we also found that annealing resulted in an increase in strength and a decrease in ductility, which was contrary to the behavior of conventional metal materials.

The Effect of Replacing Ni with Mn on the Microstructure and Properties of Al2O3-Forming Austenitic Stainless Steels: A Review.

Al2O3-forming austenitic steel (AFA steel) is an important candidate material for advanced reactor core components due to its excellent corrosion resistance and high temperature strength. Al is a strong ferrite-forming element. Therefore, it is necessary to increase the Ni content to stabilize austenite. Ni is expensive and highly active, and so increasing the Ni content not only increases the costs but also damages the radiation resistance. Mn is a low-cost austenitic stable element. Its substitution for Ni will not only help to improve the irradiation resistance of austenitic steel, but also reduce the cost. In order to explore the feasibility of Mn-substituted Ni-stabilized austenite in AFA steel, this paper summarized the research progress of Mn-added AFA steels, whilst the research status of traditional Mn-added austenitic steels are also referred to and compared herein. The effect of the addition of Mn on the microstructure and properties of AFA steel was analyzed. The results show that Mn can promote the precipitation of the M23C6 phase and inhibit the precipitation of the B2-NiAl phase and secondary NbC phase. With the increase in Mn content, the strength of AFA steel at room temperature and high temperature decreased slightly, the room temperature elongation increased slightly, while the high temperature elongation and creep resistance decreased obviously. In addition, for austenitic steel free of Al, the addition of Mn will destroy the oxide layer of Cr2O3, which will decrease the oxidation resistance of the steel. But the preliminary study shows that Mn has little effect on the Al2O3 oxide layer. It is worth studying the effect of Mn-substituted Ni on the oxidation resistance of AFA steel. In summary, more efforts are necessary to investigate the optimal Mn content to balance the advantages and disadvantages of introducing Mn instead of Ni.

Phase equilibria, thermodynamic assessment, and the mechanical property of B2 phase of the Al-Ga-Ni ternary system

Ni-based alloys, known for their exceptional mechanical properties and high corrosion resistance in harsh environments, are extensively utilized in gas-turbine engines for propulsion and energy generation. Of particular interests are the L12-Ni3Al and B2-NiAl phases in Al-Ni alloy, which can be the strengthening phases for superalloy and high temperature structural materials, respectively. After Ga addition in the Al-Ni system, these promising intermetallic compounds form a continuous compositional range encompassing the L12-Ni3(Al, Ga) and B2-Ni(Al, Ga) phases. They exhibited distinct mechanical properties contingent on the ratio of Al to Ga. Additionally, Ni and Al are the commonly used substrates in the electronic package and Ga has been used as a filler material for interconnection. Hence, the Al-Ga-Ni phase equilibria are of practical importance for designing L12-Ni3(Al, Ga) and/or B2-Ni(Al, Ga) phase-dispersed Ni-based alloys as well as for evaluating interfacial reactions in the Al/Ga/Ni contacts. However, the Al-Ga-Ni ternary system remains relatively unexplored. In this study, Al-Ga-Ni isothermal sections at 600 (Ni-lean), 900, and 1000 (Ni-rich) °C were experimentally constructed based on equilibrated alloys. Additionally, a CALPHAD-type thermodynamic assessment for the Al-Ga-Ni ternary system was comprehensively performed based on all available experimental information. Furthermore, the Young's modulus and hardness of four B2-Al(Ga, Ni) compounds were determined, revealing that the addition of Ga to B2-NiAl phase would lead to a significant decrease in Young's modulus but a notable enhancement in hardness.

Oxidation and dissolution behavior of FeCrNiAl based high entropy alloy and alumina-forming austenitic steel exposed to lead-bismuth eutectic (LBE)

Developing corrosion-resistant alloys is essential for the application of lead-cooled fast reactors. Herein, two types of FeCrNiAl alloys (high entropy alloy, HEA and alumina forming austenitic steel, AFA) are fabricated and their long-term corrosion (up to 3000 h) in lead-bismuth eutectic (LBE) at high temperature are investigated. Both alloys illustrate oxidation and dissolution behaviors, a Cr-Al enriched layer forms on AFA and the B2-NiAl phase in HEA demonstrates outstanding oxidation resistance and stability in LBE. This work offers guidelines for alloy design, especially optimizing the phase distribution of new nuclear materials that to be used in LBE.

Effect of aluminium addition on the oxidation and carburization behaviour of austenitic stainless in high-temperature SCO2 environments

The AFA stainless steels with 2.5 and 5 wt% Al were developed, and Al addition had a great influence on intermetallic compounds in AFA alloys, especially resulting in increasing of B2-NiAl phase. After 3000 h exposure in SCO2, the thickness of oxide scales for two AFA alloys was 5–7 times thinner than that of ASS without Al, and the structure of formed oxide scale significant changed, i.e., from single Cr2O3 to double-layer with Fe/Cr oxide and Al oxide. As for AFA-2.5%, the formed Al-riched oxide inner layer was amorphous and unstable, resulting in the severe internal oxidation and carburization occurrence.

Influences of Cu on microstructure and mechanical properties in Fe–Ni–Al ultra-strong maraging steels

Although the influences of Cu on microstructure and mechanical properties have been extensively studied in low-alloy steels, the aging behavior of high-alloy maraging steels with Cu remains elusive. In this work, we systematically investigated the nanoprecipitation behavior and their effects on mechanical properties in Fe–Ni–Al ultra-strong maraging steels by introducing different amounts of Cu. Structural analyses with atom probe tomography (APT), transmission electron microscopy (TEM) and small angle neutron scattering (SANS) indicate that the addition of Cu promotes the precipitation of nanoscale B2–NiAl phases in the Fe–Ni–Al ultra-strong maraging steels. The primarily precipitated Cu-clusters can serve as the nucleation sites for the precipitation of B2–NiAl at the early stage of aging, and then are dissolved into the B2–NiAl nanoprecipitates, which increases the lattice misfit between the B2–NiAl and the matrix and thereby the growth rate of B2–NiAl. As a result, the addition of 0.6 wt% Cu significantly improves the ductility of the Fe–Ni–Al ultra-strong steel without sacrificing strength. With 0.6 wt% Cu added to the Fe–Ni–Al ultra-strong steel, the elongation increased from 3.2% to 8.7% while the strength remained 2.0 GPa, due to the high-density precipitation of Ni(Al, Cu) nanoparticles. The underlying mechanisms for the precipitation behavior and the precipitation strengthening effect were discussed in terms of lattice misfit, Cu segregation and stress field.

A novel ODS high-entropy composite with improved strength and ductility

Body-centered cubic (BCC) structured high-entropy alloys (HEAs) usually exhibit excellent strength, thermal stability, irradiation tolerance and corrosion resistance but low ductility. In this study, a novel oxide dispersion strengthened (ODS) AlCrFeNi high entropy composite (with BCC-structure reinforced by face-centered cubic (FCC) ODS-CoCrFeNiMn HEA reinforcement was designed and prepared by mechanical alloying and spark plasma sintering. The effects of sintering temperatures (950 °C, 1000 °C, 1050 °C and 1100 °C) and reinforcement amount (5%, 10%,15% and 20%) on microstructure and mechanical properties were investigated. The results showed that the optimal sintering temperature of the ODS AlCrFeNi composites is 1100 °C. The hardness decreases with the increase of the reinforcement content (from 5% to 20%). Compared to the reference alloy (RA) without the addition of reinforcement, the compressive strain of the composite with 15% reinforcement (B–15%F) increases significantly from 8% (RA) to 18%, while the compressive strength increases from 2823 MPa (RA) to 3078 MPa. The B–15%F is composed of matrix, reinforcement and intermediate transition regions. The thickness of transition regions increases with increasing sintering temperature. The matrix consists of fine BCC FeCr phase and B2 NiAl phase, due to spinodal decomposition, together with high-density nanoscale oxides Y4Zr3O12 and a small amount of Y–Al–O. Surprisingly, the crystal structure of reinforcement transforms from FCC into the BCC during SPS. Meanwhile, the mutual diffusion of Al elements in the matrix and Co and Mn elements in the reinforcement also results in similar spinodal decomposition in the reinforcement. The domain size of spinodal decomposition in the reinforcement is coarser than that in the matrix. The reinforcement is mainly distributed on the prior particle boundaries (PPBs), which can effectively reduce/suppress the formation and propagation of micro-cracks along the PPBs, and thus improve both the strength and ductility of the composite.