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Titanium carbide (TiC) nanoparticles with well‐designed exposed crystal planes perform intriguing prospects for functional and engineering applications. In this study, a simple and controllable in situ synthesis strategy was proposed for the synthesis of TiC nanoparticles with specific morphology. Reaction behaviors suggested that most of TiC nanoparticles were formed by an instantaneous reaction between Al3Ti and Al4C3 in the Al‐rich melt and the resultant morphology was controlled by the discrepant growing rates of (100) and (111) crystal planes. In addition, a growth morphology control model was presented for the prediction and manipulation of the morphology of TiC nanoparticles by the doping of different alloying elements Me (Me = Cu, Mg, Mn, Zn, and Si). According to the morphological observations and density functional theory analyses including the interface energy, charge density differences, and orbital hybridization: Cu, Mg, and Zn atoms could stabilize the Al/TiC(111) interface, whereas Mn and Si atoms promoted the rapid growing and disappearance of the TiC(111) planes in the Al melt. This work provides a feasible way to intelligently design and manipulate TiC nanoparticles with desirable exposed crystal planes, and exhibits a promising prospect for personalized applications. [ABSTRACT FROM AUTHOR]

The morphology of TiC x nanoparticles is one of the most significant inherent factors that influence their comprehensive performances and extensional applications. However, the design of TiC x nanoparticles and their growth morphologies manipulating in the Al melt are always in challenges, while the stoichiometric ratios controlled synthesis will show a promising prospect. In this study, TiC x ceramic nanoparticles with different stoichiometric ratios (x = 0.5, 0.625, 0.75, 0.875 and 1.0) were fabricated successfully by combustion synthesis in Al-Ti-C reaction system. Based on the evaluation of nanosized TiC x specific exposed planes in the Al melt, the stoichiometric ratios manipulated the Al/TiC x interface performances, including interfacial stability, the nature of bonding and the interface electron transfer were analyzed via first-principle calculation. With the increasing stoichiometric ratios, the TiC x (100) exposed planes in the Al melt gradually stabilized and became exposed, while the TiC x (111) planes showed poor stability and gradually shrank and disappeared. The corresponding morphology will also evolve from octahedron to truncated-octahedron then spheroid with increasing x. Moreover, those interface performances can be selectively controlled by the stoichiometric ratio of TiC x nanoparticles. Finally, morphologies with specific exposed crystal planes in the Al melt can be effectively designed and manipulated for various applications. Unlabelled Image • TiC x nanoparticles with specific exposed surfaces were in-situ synthesized controllably in Al melt by combustion synthesis. • TiC x nanoparticles evolved from octahedrons, truncated-octahedrons to spheroids with the increasing of x from 0.5 to 1.0. • The morphology manipulating mechanism of TiC x nanoparticles was revealed by the first principle calculation of the Al/TiC x interface. • With x increasing, TiC x (100) in the Al melt gradually stabilized and exposed while (111) planes shrank and disappeared. [ABSTRACT FROM AUTHOR]

TiC/Al–Cu nanocomposites were fabricated in Al–Ti–C powder systems using carbon black, a mixture of C and carbon nanotubes (C + CNTs), and CNTs via an in-situ method involving combustion synthesis and hot pressing. As the carbon source changed from pure carbon black to the C + CNT mixture and pure CNTs, the size of the TiC nanoparticles decreased gradually. The nanocomposites synthesized based on the C + CNT mixture exhibited the most uniform dispersion of TiC nanoparticles. The 30 vol% TiC/Al–Cu nanocomposite prepared from the C + CNT mixture had the best comprehensive mechanical properties (yield strength (411 MPa), compressive strength (712 MPa), fracture strain (17.2%), hardness (206.8 HV), and wear resistance under the experimental conditions due to having the most uniformly dispersed TiC nanoparticles. The wear mechanism was a combination of plastic deformation, abrasion, and adhesion. This method may be a low-cost and convenient means to control the sizes of in-situ TiC nanoparticles and prepare high-performance TiC/Al–Cu nanocomposites. [ABSTRACT FROM AUTHOR]

[Display omitted] • Trace nanoparticles stimulated nuclei of α -Al and weakened the micro-segregation. • Nano-TiC-TiB 2 was more effective stimulating nucleation of α -Al. • Nano-TiC-TiB 2 was more effective in promoting and hindering recrystallization. • The nucleation rate of Al 2 Cu was increased by trace nanoparticles during aging. In this paper, we took cold-rolled Al-Cu 5.0 -Mg 0.5 -Si 0.5 alloy as the research object. The roles of 0.1 wt% in-situ nano-TiC and nano-TiC-TiB 2 in solid–liquid and solid-state transformations (solution plus aging precipitation) were systematically investigated and compared. We found that trace in-situ nanoparticles can stimulate the nucleation of α-Al dendrites and hinder their growth, meanwhile serving as the heat storage and heat sustained-release carriers during solid–liquid transformation. In the process of solid-state transformation, recrystallization nucleation is promoted, and grain boundaries are pinned by nanoparticles. Meanwhile, the nucleation of Al 2 Cu is accelerated, and refined Al 2 Cu distributes more uniformly. Besides, similarities and differences in the manipulation mechanisms of nano-TiC and nano-TiC-TiB 2 during solid–liquid and solid-state transformations were analyzed. The mechanical properties and the responsible strengthening mechanisms were discussed in detail. [ABSTRACT FROM AUTHOR]

Abstract Relatively high strength and good ductility are rarely obtained simultaneously in aluminum matrix composites. In the present work, dual-phased TiC n -Al 3 Ti m (n: nanosized TiC particles and m: micron-sized Al 3 Ti particles) particles were in situ synthesized in an Al-Ti-C system via the combustion synthesis method. Subsequently, (TiC n -Al 3 Ti m)/Al hybrid composites were readily fabricated at high addition levels (0, 1, 3, 5 and 7 vol%) via the re-melting and diluting method assisted ultrasonic vibration. Then, the isolated influences of the dual-phased TiC n -Al 3 Ti m particles on the solidification behaviors, microstructure evolution and mechanical properties, at both ambient- and elevated-temperatures, of aluminum alloys were systematically investigated. The experimental results revealed that the α-Al dendrites were substantially refined with a reduction of up to 4 times when compared with that of the unreinforced base alloy. Furthermore, at ambient temperature, 5 vol% (TiC n -Al 3 Ti m)/Al exhibited the optimum comprehensive mechanical properties, and the yield and ultimate tensile strength were 124.3% and 165.2% higher than those of the unreinforced base alloy, whilst the fracture strain was not sacrificed. Theoretical calculations suggest that thermal-mismatch and Orowan strengthening effects contributed most to the yield strength increment, whereas the favourable fracture strain was achieved mainly due to grain refinement. Moreover, at elevated temperature (453 K), the yield strength and ultimate tensile strength were improved by 327.8% and 236.1%, respectively, whilst the fracture strain was still at a relatively high level of 29.2%. The improved thermal resistance primarily resulted from the pinning effects of the TiC n -Al 3 Ti m particles on the grain boundaries and dislocations. Highlights • Novel dual-phased TiC n -Al 3 Ti m particles were in situ synthesized. • TiC n -Al 3 Ti m exerted refinement by heterogeneous nucleation and inhibited growth. • TiC n -Al 3 Ti m enhanced strength at 298 K by thermal mismatch and Orowan effects. • TiC n -Al 3 Ti m enhanced strength at 453 K by pinning and retarding effects. [ABSTRACT FROM AUTHOR]

It is challenging to concurrently control the microstructure evolutions after undergoing casting, sheet forming and welding. This study successfully addressed this challenge via trace TiC–TiB 2 nanoparticles in the amelioration of solidification-rolling-welding microstructural evolution. Nanoparticles refined the solidified microstructures and significantly increased the net driving force for recrystallization, promoting the precipitation of nanoscale Guinier–Preston zones and β'' phases. The coarsening of the fusion and heat-affected zones was also effectively suppressed. The yield strength (YS) and ultimate tensile strength (UTS) of the rolled plates were enhanced by 31.3% and 16.3%, respectively, without significantly sacrificing ductility. Additionally, the YS and UTS of the as-welded welding joints were enhanced by 30.2% and 7.8%, respectively. The amelioration mechanism of TiC–TiB 2 throughout the microstructural evolution and strengthening process was systematically investigated. This study provides a typical model for the complete amelioration of microstructural evolution in aluminum alloys under multiple processing conditions. • The nucleation of solidified phases is promoted, and their growth is hindered. • Recrystallization and formation of coherent nanoscale precipitates are promoted. • Coarsening of fusion zone and heat affected zone is suppressed. • Building better microstructure configuration for improved properties. [ABSTRACT FROM AUTHOR]