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The present work investigated the influence of TiC nanoparticles on the microstructure and corrosion performance of a cast superalloy K4169. The eutectic Laves phase is reduced and the as-cast grain size is refined by adding 0.02 wt.% TiC. The formation of δ phases (Ni3Nb) during heat treatments is also suppressed. Thus, the K4169 superalloy with TiC nanoparticles shows better corrosion resistance in sulfuric acid solution (10 vol.% H2SO4 solution). This work provides a strategy to effectively improve the corrosion resistance of conventional cast superalloys. [ABSTRACT FROM AUTHOR]

The addition of TiC nanoparticles induced a refined basket-weave structure, replacing coarse α colonies in cast Ti-2.5Al. Thus, the yield strength and elongation of Ti-2.5Al+TiC are increased by 46.3 % and 57.6 %, respectively. The effect of TiC nanoparticles on the grain refinement and tensile properties is more pronounced than the addition of elemental C. [ABSTRACT FROM AUTHOR]

The oxygen and nitrogen interstitial solutes strongly resist the motion of dislocations in titanium alloys, which accounts for the improvement of strength and the loss of ductility. In this study, compressive properties of L-PBF Ti64 with high oxygen and nitrogen content are improved by adding trace nanoparticles (0.1 wt% TiC + TiB) and CALPHAD-based design of heat treatments for the first time. The strength and plasticity of Ti64 increase by 8.8 % and 29.2 % respectively with the addition of nanoparticles before heat treatment. A good combination between strength and plasticity is obtained by solution treatment at 1040 °C and subsequently air-cooling (1040-AC) with the addition of nanoparticles. Compared to the L-PBF Ti64, the plasticity of TiC + TiB/Ti64 increases by 100 % without losing compressive strength after 1040-AC. A bi-modal structure including hard primary α phase and ductile secondary fine α lamellae, was obtained after 1040-AC, which is beneficial for its ductility and work-hardening. The addition of nanoparticles promotes the refinement and uniform distribution of the secondary α lamellae during cooling, which results in high strength and the distribution of α/α boundary being close to the theoretical random frequencies. Therefore, the TiC + TiB/Ti64 after 1040-AC exhibits excellent compressive strength and plasticity. [ABSTRACT FROM AUTHOR]

Al-5Cu-0.8Mn-0.1Zr strips produced during a twin-roll-casting process are investigated in this paper. Central segregation does occur in the alloy strip, and the segregation is a mixture of Al2Cu and Al20Cu2Mn3 eutectic phases. This mixture is difficult to be dissolved in solid solution heat treatment. In this paper, nano-sized TiC/TiB2 particles are introduced in the process of twin-roll-casting. It was found that after adding 0.3% nano-sized TiC-TiB2 particles, the composition distribution becomes more uniform, and the central segregation is eliminated, compared to the strip without nanoparticles. The tensile strength of T6-treated alloy increases from 350 MPa to 390 MPa when nanoparticles are added, and the goal of increasing the properties of twin-roll-cast Al-Cu-Mn-Zr alloy has been achieved. [ABSTRACT FROM AUTHOR]

A novel strategy for the rapid synthesis of high‐entropy carbide particles is proposed that involves the transformation of multicomponent intermetallic intermediates to multicomponent carbides (high‐entropy carbide precursors). (Ti0.25V0.25Nb0.25Ta0.25)C nanoparticles with a uniform solute distribution were successfully synthesized in an Al matrix by heating Al‐Ti‐V‐Nb‐Ta‐C powder mixtures at 1500°C for 10 minutes. The multicomponent aluminide intermediates led to the rapid formation of multicomponent carbides during heating to 1100°C, which transformed into a high‐entropy solid solution during heating to 1500°C. We developed a new rapid approach for the synthesis of high‐entropy ceramic particles. [ABSTRACT FROM AUTHOR]

The increase in strength usually accompanies with ductility loss in structural materials. We proposed a novel approach to the design and fabrication of hierarchically structured Al-Mg-Si alloys/nanocomposites with improved strength and ductility. The layered distribution of TiC nanoparticles (TiCp), bimodal-sized grains and precipitates were produced in a laminated composite composed of Al-Mg-Si matrix alloy and TiCp/Al-Mg-Si composite by accumulative roll bonding (ARB), increasing yield strength from 380 MPa to 443 MPa with a uniform elongation from 5.0% to 6.4%, compared to the ARB TiCp/Al-Mg-Si composite. This work provides a new strategy for producing high strength composite sheets for industrial applications. A hierarchical structure with the layered distribution of nanosized TiC particles (TiCp) was obtained through the master alloy-casting process and accumulative roll bonding process. Significant improvement in strength was obtained with no loss in ductility. [ABSTRACT FROM AUTHOR]

In this work, Al-5Cu and TiC/Al-5Cu strips were fabricated by vertical-type twin-roll casting (TRC), and the effects of TiC nanoparticles on the Al-Cu strips were investigated. The minor addition of TiC nanoparticles refined the grain structure, increased the Cu concentration in the α-Al dendrites and effectively mitigated the center macro-segregation of the as-cast strip, which could be due to the heterogeneous nucleation effect and the solute diffusion control of the TiC nanoparticles. The yield strength, ultimate tensile strength, and uniform elongation of the as-cast, as well as T6 treated Al-5Cu strip with the addition of TiC nanoparticles were simultaneously improved owing to fewer residual Cu-rich phases, refined θ′ precipitates, and finer grain structure. This work provided a strategy for the effective control of macro-segregation and producing high-formability alloy strips by the TRC process. [ABSTRACT FROM AUTHOR]

In this work, a high strength–ductility Ti64 cast alloy, containing trace TiC-TiB2 nanoparticles, was fabricated by adding dual-phased nano-TiC-TiB2/Al master alloys to the molten Ti64 alloys. The trace addition of the TiC-TiB2 nanoparticles (0.1 wt%) simultaneously reduced the size of the β grains, the α laths, and the α colony size of the lamellar structure during casting and suppressed the coarsening of the α laths during heat treatment. The yield strength and the uniform elongation of TiC-TiB2/Ti64 were increased by ~130 MPa and 2%, respectively. The simultaneously improved strength and ductility of the TiC-TiB2/Ti64 were attributed to the decrease in the α colony size of the lamellar structure, the significant refinement of the grains and α laths, and the pinning effect of nanoparticles. [ABSTRACT FROM AUTHOR]

In this work, the effects of cooling rate and the addition of TiC nanoparticles on the as-cast microstructure, precipitation behavior during subsequent heat treatments and mechanical properties were investigated. The grain size (GS), secondary dendritic arm spacing (SDAS) and primary particle size are the function of cooling rate v , following a similar power law, D = Av -n (D is the size of grains/SDAS/primary particles, A and n are constants). The TiC addition reduced the A value for grain size and primary particles but increased A for SDAS. The addition of TiC nanoparticles promoted the coarsening of secondary dendritic arms, leading to the reduced microsegregation and smaller interdendritic/intergranular secondary phase (Al 2 Cu). Consequently, the precipitation of the θ′ phase during ageing treatment was promoted, and the precipitates were refined and more dispersive, contributing to the increased tensile strength. The improved ductility was ascribed to the combination of reduced secondary phases and micropores. With the combination of high cooling rate and TiC addition (cooling rate: 93 °C/s; 0.5% TiC addition), the yield strength, ultimate tensile strength and uniform elongation of the Al–5Cu cast alloy were simultaneously improved, and reached those of Al–5Cu rolled sheet. [ABSTRACT FROM AUTHOR]

Fatigue resistance and fracture toughness are essential to the reliability of castings during service. Reducing microporosity in cast alloys is a crucial issue for improving their fatigue strength and fracture toughness. Here we report a significant reduction in microporosity of a cast aluminum-copper alloy developed using in situ TiC nanoparticle additions coupled with a stir-casting method. The addition of TiC nanoparticles is found to improve the interdendritic feedability of liquid metal and as a result reduces the volume fraction of microporosity by two orders of magnitude compared to a conventionally cast Al–Cu alloy. This method, which is mechanistically associated with a pore-dominated process, acts to significantly improve the fatigue strength, fracture toughness and uniform elongation of the cast Al–Cu alloy to values which, to the best of our knowledge, represent the highest ever achieved for a cast aluminum alloy. Image 1 • A significant porosity reduction is achieved in Al cast alloy through an in-situ nanoparticle master alloy method. • This method serves to uniformly add nanoparticles into metal melt and improve the bonding between particles and matrix. • The addition of TiC nanoparticles impedes the formation of porosity and thus improves the mechanical property of Al alloy. • The fatigue strength, fracture toughness and elongation of the Al alloy are improved to 114 MPa, 55 MPa m1/2 and 12%. • The mechanism of the mechanical property improvement are revealed with the aid of finite element modeling. [ABSTRACT FROM AUTHOR]

In this work, Al-Mn-Si and TiC-TiB 2 /Al-Mn-Si strips were prepared by vertical-type twin-roll casting (TRC), and the effect of TiC-TiB 2 nanoparticles (NPs) on the microstructure and mechanical properties of TRC Al-Mn-Si strips were studied. The TRC strips had the characteristics of coarse grains near the surface and fine grains in the center. The introduction of NPs resulted in the formation of uniform and fine grain structures due to the grain refinement effect of NPs. The refining effect on the surface grains was much greater than that on the central grains because the larger thermal undercooling of the melt at the surface led to the improvement of the nucleation efficiency of NPs. TiC-TiB 2 particles could eliminate the central segregation of TRC Al-Mn-Si strips due to the control of solute diffusion by the uniform and fine grain structures, thereby reducing α-Al(Mn, Fe)Si formation in the central region. The mechanical properties of the TRC Al-Mn-Si strips were improved with the introduction of NPs. The yield strength at room temperature was increased from 79.0 MPa to 92.9 MPa, and the uniform elongation was increased from 7.2% to 10.1%, due to the fewer eutectic α-Al(Mn, Fe)Si, refined precipitates and grain structures caused by the addition of the TiC-TiB 2 particles. • The TRC strips had the characteristics of coarse grains near the surface and fine grains in the center. • The refining effect on the surface grains was much greater than that on the central grains of the TRC strips. • TiC-TiB 2 particles could eliminate the central segregation of TRC Al-Mn-Si strips. • The introduction of TiC-TiB 2 particles could improve the mechanical properties of the TRC Al-Mn-Si strips. [ABSTRACT FROM AUTHOR]

In this work, a Ni–Fe based cast superalloy (K214) containing 0.02 wt% TiC nanoparticles was fabricated by the vacuum induction melting, and the effects of TiC nanoparticles on the microstructure and tensile properties of the alloys were investigated. The trace addition of TiC nanoparticles effectively refined the as-cast grains, promoted the coarsening of secondary dendrite arms, and reduced microsegregation. The yield strength, ultimate tensile strength and elongation at room/elevated temperatures were simultaneously improved, which could be ascribed to reduced microsegregation and refined γ′ precipitates. This work provides a strategy for the effective improvement in the mechanical properties of cast superalloys fabricated by the conventional casting process. [ABSTRACT FROM AUTHOR]

The present work investigated the synergistic effects of the TiC nanoparticles (NPs) and cold rolling on the microstructure and mechanical properties of Al–Cu strips fabricated by twin-roll casting (TRC). The trace addition of NPs effectively promoted the columnar-to-equiaxed transition along with a refined grain structure, and the macrosegregation of the as-cast TRC strip was well mitigated. The introduction of the cold rolling further refined the grains and accelerated the dissolution of the coarse second phases after subsequent solution treatment, and combined with the effect of NPs, the precipitation kinetics was greatly promoted during the aging treatment. The precipitates were well refined and the distribution was more uniform. The yield strength, ultimate tensile strength, and uniform elongation of the TRC strips with the TiC addition and cold rolling were simultaneously improved after T6 heat treatment. This work aims to provide a strategy for producing high-strength alloy strips with the high-formability by the TRC process. [ABSTRACT FROM AUTHOR]