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For the development of new energy automobile industry and the trend of automobile lightweight have put forward a huge demand for high-strength lightweight materials, so developing high strength aluminum alloys is particularly momentous. As the most widely used aluminum alloy, 6000 series aluminum alloys (Al–Mg–Si alloys) have the advantages such as better mechanical properties, outstanding welding properties, excellent formability and fine processing capability, and therefore have obtained great attention as the structural materials. In addition, the Al–Mg–Si alloys with low density and corrosion resistance not only reduce the total weight of the car, but also extend the service life when subjected to chemical corrosion, which effectively achieve energy saving and emission reduction. This paper summarizes the research progress of 6000 series aluminum alloys, in particular, and reviews the methods of microalloying and particle strengthening, and their effects on the microstructure and properties of the alloy, thus providing a reference for the subsequent development of high-performance aluminum alloys in automobile and aerospace industries.

Rapid growth in industrial sectors such as automotive and shipbuilding has highlighted the significance of strip casting technology to produce lightweight alloys, particularly aluminum alloys widely used in both industrial production and daily life. Twin-roll casting (TRC), as an economically and environmentally friendly method for slab/strip production and processing, has attracted significant interest from researchers. However, the development of TRC aluminum alloys faces many challenges due to limited understanding of microstructural characteristics and control mechanisms. To further enhance comprehension of TRC aluminum alloys, this article reviews the influencing parameters, control methods, and existing issues related to TRC sub-rapid solidification (SRS) microstructure. It firstly summarizes TRC equipment types and their solidification characteristics, followed by a detailed analysis on key parameters affecting the evolution of TRC microstructure including rolling speed, roll separation force (RSF), and heat transfer coefficient (HTC). Finally, solutions to TRC defects are summarized and evaluated alongside their underlying mechanisms. This article provides a comprehensive review of the characteristics and control mechanisms of TRC microstructure while offering valuable insights for the future production of high-quality TRC aluminum strips.

In the global pursuit of energy conservation, reduction in consumption and emissions, as well as lightweighting, 5xxx-series aluminum alloys have emerged as a promising lightweight and high-strength material with a wide range of applications in aerospace, transportation, building structures, medical devices, and more. However, it is worth noting that 5XXX-series aluminum alloys belong to a category of non-heat-treatable reinforced aluminum alloys with limited means of enhancing their properties through heat treatment. Consequently, the development of high-performance 5XXX-series aluminum alloys poses a significant challenge. This paper provides an overview of the research progress on 5xxx-series aluminum alloys while discussing the current state of research regarding the influence of microalloying elements on their microstructure and properties. Furthermore, it elucidates the emerging trends in synergistic regulation between deformation processes and heat treatment processes for enhancing organizational refinement and improving alloy properties. Additionally, this study analyzes the reinforcement mechanism responsible for the exceptional properties exhibited by 5xxx-series aluminum alloys. Lastly, it discusses the exceptional properties exhibited by 5xxx-series alloys along with their primary areas of application. The findings presented herein can serve as a valuable reference for future advancements in advanced high-performance 5xxx-series aluminum alloys.

Rock breaking has always been a challenging problem that must be solved in projects such as excavating mountains, drilling wells, and constructing railways. Among the rock-breaking cutter steels, AISI H13 steel and wear-resistant high manganese steel have become the best choices. From the characteristics and failure modes of the two, rock-breaking cutter steels should simultaneously have high strength, high toughness and high wear resistance to avoid short-term fracture/damage and cost increase. Analyzing the problems existing in the molding process of rock-breaking cutter steels such as die casting, forging, and hot stamping, traditional strengthening technologies such as alloying optimization, heat treatment, and surface treatment can achieve certain performance enhancement. After reaching the limits of traditional strengthening technologies, a series of nanoparticle strengthening technologies came into being. The selection, addition amount, and addition method of nanoparticles all affect the microstructure, mechanical properties and wear. To this end, this article summarizes the research progress and challenges of rock-breaking cutter steels, and discusses traditional strengthening technologies and mainstream nanoparticle strengthening technologies. It provides a reference for the future development of high-quality and high-performance rock-breaking cutter steels, with aim to simultaneously expand their application potentials to other fields.

The explosive growth of wireless communications and electronic devices has brought electromagnetic radiation's harmfulness and hidden trouble to light, which has a major impact on electrical equipment's ability to function normally. MXene, a material with favorable features like conductivity, a unique two-dimensional multiple-layer structure and abundant surface functional groups, has made it a viable contender for high-performance microwave-absorbers. This article introduces the synthesis strategy of MXene/MXene-based materials and their parent phase MAX, comprehensively summarizes and analyzes the current progress in the study on the microwave-absorbing properties of MXene/MXene-based materials, analyzes the main problems and bottlenecks. Future research directions for MXene microwave-absorbing are discussed in detail.

The further development of lightweight and energy-saving engineering materials is a great challenge for scientists in the 21st century. Magnesium and its composites, as the metal materials with the lowest density among metal structural materials, have good thermal conductivity, good dimensional stability, high specific strength, good biocompatibility, which can meet the requirements of energy-saving, emission reduction, environmental protection. In recent years, magnesium and its composites have found the major applications in various fields such as aerospace, automotive industry, electronics and medical industry. However, the fabrication of magnesium matrix composites is difficult, and the deformation behaviors and strengthening mechanisms of particulate reinforced magnesium matrix composites have unique characteristics. This article reviews the recent research progress of the magnesium matrix composites, including different fabrication methods and strengthening mechanisms. According to the classification of solidification rate, the advantages and disadvantages of various techniques used to fabricate magnesium matrix composites were introduced. The traditional and novel fabrication techniques were discussed. The influence mechanisms of particulates on solidification microstructures, recrystallization behaviors, texture strength and twin behaviors of magnesium matrix composites during solidification and extrusion were summarized, and the roles of particulates in solidification and extrusion of magnesium matrix composites were analyzed. The strengthening mechanisms of particulates on the mechanical properties, corrosion resistance, fatigue resistance and creep resistance of magnesium matrix composites were revealed. Finally, the development prospect and research direction of magnesium matrix composites were prospected. It is hoped that this paper can provide a reference for the further development of magnesium matrix composites.

Magnesium alloys, acknowledged as the environmentally-friendly engineering material of the 21st century, are ideally suited to fulfill the requirements of lightweight manufacturing. However, the poor plasticity of magnesium alloys hampers their further application. Subsequently, development of nanoparticle-reinforced magnesium matrix composites has been proven to be a promising way to enhance the comprehensive performance of magnesium alloys. The exceptional performance achieved even by very small number of reinforcements stimulated innovation in preparation techniques and in-depth analysis of reinforcement mechanisms. This paper provides a review on key challenges related to their processing, the profound impact of different micro-nanoparticle reinforcements on the microstructure and properties of magnesium matrix composites during solidification and subsequent deformation machining. Additionally, the reinforcement mechanisms of the excellent mechanical performance of the composites are also discussed. This study can provide valuable insights for the understanding of the selection of appropriate reinforcements and processing to optimize the performance nanoparticle-reinforced magnesium matrix composites.

This paper focuses on the effects and mechanisms of rare earth and calcium on the flame retardancy of magnesium alloys. Rare earth elements form dense composite oxide films on the surface of the melt, effectively inhibiting the progress of oxidation reactions and significantly increasing the ignition temperature of magnesium alloys. The mechanisms and optimal compositional ranges of different rare earth elements on the flame retardancy of magnesium alloys. Calcium form CaO-rich oxide films in magnesium alloys, which can effectively prevent oxygen diffusion and enhance the flame-retardant resistance of the alloy. When rare earth elements are compounded with calcium, a notable flame-retardant effect is observed. Composite application can maximize the flame-retardant effect of alloy elements while balancing the influence on various properties. Additionally, the authors illustrate through their own research that precise compositional optimization design is required to efficiently exploit the synergistic effects of RE and Ca and mitigate their adverse impacts.

Cold/hot forming wrought Al components with the apparent advantage of lightweight, outstanding formability and strength-ductility synergy are promising in structural materials field. Recrystallization is an indispensable process during deformation or heat treatment, whose driving force and microstructures have great relevance with the mechanical properties. In recent years, reinforcement and intermetallic particles have attracted great interests in precise intervening and controlling of recrystallization microstructures due to their immense potentials in regulating the driving and retarding force of recrystallization. Nevertheless, optimizing recrystallization microstructures of particle tailored wrought Al alloys is highly challenging due to the numerous affecting factors of particles (e.g., particle addition method, size, morphology, spatial distribution, coherency, and content, etc.) and the different driving force of static and dynamic recrystallization. To further impel the progress of recrystallization process of wrought Al alloy, this review gives an in-depth cognition of the roles of intermetallic and ceramic particles in recrystallization process of wrought Al alloys. The potential relevance between the particle characteristics, recrystallization driving force, and recrystallization microstructures in wrought Al alloys are summarized. The influences of regulated recrystallization microstructures on mechanical properties of wrought Al alloy are also overviewed. This review contributes to the comprehensive understanding of mechanisms of particle manipulated recrystallization evolution, and the future research orientations and development opportunities are prospected.

There is an increasingly urgent need of lightweight components in aerospace industry, among which aluminum (Al) alloys have been the optimal materials of choice for aircraft structural parts since being used in the Junkers F.13 aircraft in the 1920s. Compared to other metal materials, Al alloys have a lower density, and the use of Al alloys reduces the total weight of the aircraft and improves fuel efficiency and load capacity. Meanwhile, the strength and hardness of Al alloys with alloying and heat treatment can be significantly enhanced for uses in high loads and vibration environments. Furthermore, in the harsh aerospace environment, aircraft may receive various climatic conditions and chemical corrosion. Due to good corrosion and fatigue resistance, Al alloys demonstrate excellent performance under these conditions, ensuring the long–term service life of aircraft. In addition, Al alloys have good recyclability, and they can be recycled to reduce resource consumption and environmental load, in line with the principle of sustainable development. In recent years, although composites have been widely used in aerospace, high–strength Al alloys are still in an indispensable position. Therefore, this article reviews the progress and applications of Al alloys commonly used in aerospace. The common strengthening methods and advanced manufacturing and processing technologies of Al alloy are also discussed, which can provide references for the development of advanced high–performance aviation Al alloys in the future.

The mechanical performance of metal matrix composites strengthened with particles is predominantly contingent upon the attributes of the incorporated particles. Attaining the optimal particle size, morphology, and interfacial bonding within the composites is paramount for improving the comprehensive properties. In this study, an experimentally congruent model was devised to validate the feasibility of the model predicated on the actual microstructure of the composite. The modeling procedure encapsulated matrix and particle failure, as well as surface-based cohesive damage at the interface, to precisely portray the mechanism of action for the particle characteristics. Additionally, the mechanical behavior and failure evolution mechanism of the composites were simulated by manipulating the pertinent particle factors, including size distribution, interfacial strength, and morphology. The findings demonstrated that an appropriate size distribution between particles and more rounded particles can mitigate stress and strain concentration within the matrix interstitial to particles, resulting in a considerable enhancement in the mechanical performance of the composites. As the interfacial strength decreases, the initial failure progression of the composite shifts from initial cracking within the matrix induced by stress-strain concentration to interfacial failure caused by interfacial debonding, ultimately accelerating the failure of composite. This research will bolster the comprehension of the correlations between microstructural features and mechanical performance in metal matrix composites strengthened with particles, providing an innovative simulation-assisted experimental approach for the rapid development and preparation of novel metal matrix composites.

Al-Mg alloys are widely used as important engineering structural materials in aerospace engineering, transportation systems, and structural constructions due to their low density, high specific strength, corrosion resistance, welding capability, fatigue strength, and cost-effectiveness. However, the conventional Al-Mg alloys can no longer fully satisfy the demands of practical production due to difficulties caused by many defects. The high strength of Al-Mg alloys as non-heat treatment precipitation-strengthened alloys is achieved primarily by solid solution strengthening along with work hardening rather than precipitation strengthening. Therefore, severe plastic deformation (SPD) techniques can be often used to produce ultrafine-grained structures to fabricate ultra-high strength aluminum alloys. However, this approach often achieves the strengthening of material at the cost of reduced ductility. This paper comprehensively summarizes the various approaches of ultrafine/nanocrystalline materials for enhancing their plasticity, elaborates on the creation of a bimodal microstructure within the alloy, and discusses the formation of a nanotwin microstructure within the alloy and the incorporation of dispersed nanoparticles. The mechanisms underlying both the strengthening and toughening during large plastic deformation in aluminum alloys are summarized, and the future research direction of high-performance ultrafine crystalline and nanocrystalline Al-Mg aluminum alloys is prospected.

As an important part of die steels, hot-work die steels are mainly used to manufacture molds made of solid metal or high-temperature liquid metal from heating to recrystallization temperature. In view of the requirements for mechanical properties and service life for hot-work die steel, it is conducive to improve the thermal fatigue resistance, wear resistance, and oxidation resistance of hot work die steel. In this review, the main failure modes of hot-work die steel were analyzed. Four traditional methods of strengthening and toughening die steel were summarized, including optimizing alloying elements, electroslag remelting, increasing the forging ratio, and heat treatment process enhancement. A new nano-strengthening method was introduced that aimed to refine the microstructure of hot-work abrasive steel and improve its service performance by adding nanoparticles into molten steel to achieve uniform dispersion. This review provides an overview to improve the service performance and service life of hot work die steel.

Hot-work die steel with excellent strength and toughness can improve the precision of the die and prolong its service life. However, this is very difficult to achieve because of the opposing relationship between strength and plasticity. In this paper, we propose a combined approach of composition design and nanoparticle modification to overcome this difficulty. A novel hot-work die steel with reinforced trace nano-(TiC–TiB2) was fabricated using a traditional method. It had an improved microstructure, which consists of fine martensitic laths with high dislocation density, abundant small precipitates, and small and dispersed residual austenite. This expected microstructure improved the work hardening and uniform deformation ability of the steel, resulting in superior comprehensive mechanical properties. The yield strength and impact toughness of the novel hot-work die steel at room temperature were 1464 MPa and 597 J/cm2, respectively, increases of 121 MPa and 265 J/cm2, respectively, compared to the values for advanced and widely used traditional H13 steel. In particular, the impact toughness of the novel hot-work die steel at room temperature was approximately 42.5% and 33.0% higher than the impact toughness of H13 containing 0.01 and 0.02 wt% nanoparticles, respectively. Furthermore, the yield strength, ultimate tensile strength, and elongation of novel hot-work die steel at 500 °C were 1078 MPa,1103 MPa, and 40.4%, respectively, increases of 85 MPa, 86 MPa, and 4.2%, respectively, compared to values of the blank that was used in this work. This work shows new prospects for the development of hot-work die steel with excellent strength and toughness.

The optimal design of microstructure is the key to further improve the properties of particle reinforced metal matrix composites. In this study, in-situ TiB2 and TiC + TiB2 reinforced Cu matrix composites are used as examples to develop the microstructure-based representative volume element models to describe their damage evolution and strengthening mechanisms. The most critical features including size distribution and morphology of the particles as well as the fracture of metal matrix, brittle damage of ceramic particles and traction-separation debonding of the interface were integrated into the modeling. Simulation results show that the model could well predict the performance of the composite and reveal its damage mechanism. When the particle size is normally distributed, the composite exhibits higher strength due to the size effect of different particles, which is more consistent with the experimental result. Both matrix and ceramic particles in mixed-phase particle reinforced metal matrix composites can be subjected to higher stresses, which results in higher strength of (TiC + TiB2)/Cu composites. Additionally, the spherical TiC particles facilitate the relaxation of stress concentration within the composite, resulting in a synergistic enhancement of strength and ductility. Under compression, localized interface damage first appears around the sharp corners of the hexagonal particles and induces crack initiation toward the matrix. These microcracks are interconnected and propagate along the direction of high stress, eventually leading to the failure of the composite. This work provides the basis and new ideas to reveal the failure mechanism of composites and further optimize their configuration design.

In aluminum alloys, the most often utilized cast Al–Si alloy system, the microstructure often needs to be improved by modification and inoculation treatment. This study comprehensively examines the impact of nanocrystals produced by Fe–B–Si amorphous alloys on the solidification behavior and microstructure of hypoeutectic Al–Si7 alloy and hypereutectic Al–Si17 alloy. The nucleation temperature of α-Al is increased and the nucleation of α-Al is easier as well as crystallization platform becomes shorter. For primary Si, the nucleation temperature is decreased and the nucleation is inhibited. The eutectic transformation is promoted and the reaction time is shortened. For α-Al, in situ nano-Fe2B can act as its heterogeneous nucleation sites and promote its nucleation. Meanwhile, the growth of α-Al dendrites is constrained by nearby grains and nanocrystals that do not participate in nucleation, therefore refining the dendrites. Furthermore, nano-Fe2B promotes the eutectic transformation and refines the eutectic microstructure. At the same time, the microstructure of the eutectic groups is refined and the distribution is more dispersed due to the confinement of finer adjacent grains and the hindrance of nanocrystals that do not participate in nucleation.

Incident Ti–Si poisoning when applying traditional agents of microstructure manipulation in Al–Si alloys is always adverse to realize multilevel microstructure control. This work combined the manipulation by physically formed in-situ nano-ceramics from Fe79.58B11.26Si9.26 amorphous alloy and the micro-alloying to comprehensively improve the microstructure configuration of Al–7.0Si–4.0Cu alloy. It was suggested that micro-alloying of Mg and Sb prominently refined α-Al dendrites and eutectic silicon. Micro-alloying with Mg increased the nucleating temperature of α-Al, meanwhile Mg atoms can hinder the growth of α-Al and eutectic silicon. Sb atoms can also be adsorbed to the growth interfaces of eutectic silicon hindering the growth process. On this basis, trace Fe79.58B11.26Si9.26 amorphous alloy brought further optimization on α-Al dendrites and eutectic silicon, especially Al2Cu and Mg2Si, realizing the multilevel microstructure control. In-situ Fe2B and Fe3Si nano-ceramics were confirmed to have low lattice misfits with α-Al and silicon, serving as efficient nucleation sites and growth retardants. After combined micro-alloying and manipulation, the mean sizes of α-Al and eutectic silicon were significantly refined by 72.7% and 79.9%, respectively, meanwhile, the ultimate tensile strength (UTS) and plastic strain (δ) were improved to 480 MPa and 9.4%, corresponding to 30.1% and 77.4% improvement, respectively. This work provides new mentality to realize multilevel microstructure control and improvement of strength–toughness synergy in Al–Si alloys.

In the general environment of lightweight automobiles, the integrated die-casting technology proposed by Tesla has become the general mode to better achieve weight reduction in automobiles. The die-casting mold required by integrated die-casting technology has the characteristics of large scale and complexity. Hence, higher requirements are put forward for the comprehensive performance of the die steel. Despite the stagnation in the progress of conventional strengthening methods, enhancing the performance of die steel has become increasingly challenging. Indeed, it necessitates exploring novel die steel and optimizing heat treatment and reinforcement technologies. This article summarizes and analyzes the development status of die steel and corresponding heat treatment and microstructure manipulation as well as strengthening methods and elaborates on an excellent nano-strengthening technology. Furthermore, this review will aid researchers in establishing a comprehensive understanding of the development status of die steel and the processes utilized for its strengthening. It will also assist them in developing die steel with improved comprehensive performance to meet the high demand for mold steel in the integrated die-casting technology of the new era.

It is well known that the development of lightweight alloys with improved comprehensive performance and application value are the future development directions for the ultra-high-strength 7xxx series Al-Zn-Mg-Cu alloys used in the aircraft field. As the lightest metal element in nature, lithium (Li) has outstanding advantages in reducing the density and increasing the elastic modulus in aluminum alloys, so Al-Zn-Mg-Cu alloys containing Li have gained widespread attention. Furthermore, since the Al-Zn-Mg-Cu alloy is usually strengthened by aging treatment, it is crucial to understand how Li addition affects its aging precipitation process. As such, in this article, the effects and mechanism of Li on the aging precipitation behavior and the impact of Li content on the aging precipitation phase of Al-Zn-Mg-Cu alloys are briefly reviewed, and the influence of Li on the service properties, including mechanical properties, wear resistance, and fatigue resistance, of Al-Zn-Mg-Cu alloys are explained. In addition, the corresponding development prospects and challenges of the Al-Zn-Mg-Cu-Li alloy are also proposed. This review is helpful to further understand the role of Li in Al-Zn-Mg-Cu alloys and provides a reference for the development of high-strength aluminum alloys containing Li with good comprehensive properties.

Copper matrix composites doped with ceramic particles are known to effectively enhance the mechanical properties, thermal expansion behavior and high-temperature stability of copper while maintaining high thermal and electrical conductivity. This greatly expands the applications of copper as a functional material in thermal and conductive components, including electronic packaging materials and heat sinks, brushes, integrated circuit lead frames. So far, endeavors have been focusing on how to choose suitable ceramic components and fully exert strengthening effect of ceramic particles in the copper matrix. This article reviews and analyzes the effects of preparation techniques and the characteristics of ceramic particles, including ceramic particle content, size, morphology and interfacial bonding, on the diathermancy, electrical conductivity and mechanical behavior of copper matrix composites. The corresponding models and influencing mechanisms are also elaborated in depth. This review contributes to a deep understanding of the strengthening mechanisms and microstructural regulation of ceramic particle reinforced copper matrix composites. By more precise design and manipulation of composite microstructure, the comprehensive properties could be further improved to meet the growing demands of copper matrix composites in a wide range of application fields.

In this paper, we took cold-rolled Al-Cu5.0-Mg0.5-Si0.5 alloy as the research object. The roles of 0.1 wt% in-situ nano-TiC and nano-TiC-TiB2 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 Al2Cu is accelerated, and refined Al2Cu distributes more uniformly. Besides, similarities and differences in the manipulation mechanisms of nano-TiC and nano-TiC-TiB2 during solid–liquid and solid-state transformations were analyzed. The mechanical properties and the responsible strengthening mechanisms were discussed in detail.

High power semiconductor disk lasers (SDLs) were demonstrated based on the thermal management using pre-metalized diamond heat-spreader. The processing of pre-metallization using Cu-Sn alloy was developed. The resultant and influence of pre-metallization on the thermal performance of SDLs were investigated. It was found that the pre-metalized diamond heat-spreader was able to improve effectively not only the thermal resistance but also the bonding quality. 38% decrease on the thermal resistance of SDL was realized. The CW power exceeding 27 W, limited by the available pump power, was demonstrated.

The morphology of TiCx nanoparticles is one of the most significant inherent factors that influence their comprehensive performances and extensional applications. However, the design of TiCx 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, TiCx 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 TiCx specific exposed planes in the Al melt, the stoichiometric ratios manipulated the Al/TiCx 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 TiCx(100) exposed planes in the Al melt gradually stabilized and became exposed, while the TiCx(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 TiCx nanoparticles. Finally, morphologies with specific exposed crystal planes in the Al melt can be effectively designed and manipulated for various applications. Keywords: TiCx nanoparticles, Stoichiometric ratio, Al/TiCx interface, Growth mechanisms, Morphology evolution manipulation

It is widely known that the special performances and extensive applications of the nanoscale materials are determined by their as-synthesized structures, especially their growth sizes and morphologies. Hereinto, titanium carbides, which show brilliant comprehensive properties, have attracted considerable attention from researchers. How to give full play to their potentials in the light-weight manufacture, microwave absorption, electromagnetic protection, energy conversion and catalyst areas has been widely studied. In this summarized article, the synthesis methods and mechanisms, corresponding growth morphologies of titanium carbides and their further applications were briefly reviewed and analyzed according to their different morphological dimensions, including one-dimensional nanostructures, two-dimensional nanosheets and three-dimensional nanoparticles. It is believed that through the investigation of the crystal structures, synthesis methods, growth mechanisms, and morphology characterizations of those titanium carbides, new lights could be shed on the regulation and control of the ceramic phase specific morphologies to meet with their excellent properties and applications. In addition, the corresponding development prospects and challenges of titanium carbides with various growth morphologies were also summarized.

The nonlinearity of semiconductor quantum dots under the condition of low light levels has many important applications. In this study, linear absorption, self-Kerr nonlinearity, fifth-order nonlinearity and cross-Kerr nonlinearity of multiple quantum dots, which are coupled by multiple tunneling, are investigated by using the probability amplitude method. It is found that the linear and nonlinear properties of multiple quantum dots can be modified by the tunneling intensity and energy splitting of the system. Most importantly, it is possible to realize enhanced self-Kerr nonlinearity, fifth-order nonlinearity and cross-Kerr nonlinearity with low linear absorption by choosing suitable parameters for the multiple quantum dots. These results have many potential applications in nonlinear optics and quantum information devices using semiconductor quantum dots.

Bimodal hybrid in-situ nano-/micro-size TiC/Al composites were prepared with combustion synthesis of Al-Ti-C system and hot press consolidation. Attempt was made to obtain in-situ bimodal-size TiC particle reinforced dense Al matrix composites by using different carbon sources in the reaction process of hot pressing forming. Microstructure showed that the obtained composites exhibited reasonable bimodal-sized TiC distribution in the matrix and low porosity. With the increasing of the carbon nano tube (CNT) content from 0 to 100 wt. %, the average size of the TiC particles decreases and the compressive strength of the composite increase; while the fracture strain increases first and then decreases. The compressive properties of the bimodal-sized TiC/Al composites, especially the bimodal-sized composite synthesized by Al-Ti-C with 50 wt. % CNTs as carbon source, were improved compared with the composites reinforced with single sized TiC. The strengthening mechanism of the in-situ bimodal-sized particle reinforced aluminum matrix composites was revealed.

The nano-sized SiCp/Al–Cu composites were successfully fabricated by combining semisolid stirring with ball milling technology. Microstructures were examined by an olympus optical microscope (OM), field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). Tensile properties were studied at room temperature. The results show that the α-Al dendrites of the composites were strongly refined, especially in the composite with 3 wt. % nano-sized SiCp, of which the morphology of the α-Al changes from 200 μm dendritic crystal to 90 μm much finer equiaxial grain. The strength and ductility of the composites are improved synchronously with the addition of nano-sized SiCp particles. The as-cast 3 wt. % nano-sized SiCp/Al–Cu composite displays the best tensile properties, i.e., the yield strength, ultimate tensile strength (UTS) and fracture strain increase from 175 MPa, 310 MPa and 4.1% of the as-cast Al–Cu alloy to 220 MPa, 410 MPa and 6.3%, respectively. The significant improvement in the tensile properties of the composites is mainly due to the refinement of the α-Al dendrites, nano-sized SiCp strengthening, and good interface combination between the SiCp and Al–Cu alloys.

In order to effectively reduce energy consumption and increase range mile, new energy vehicles represented by Tesla have greatly aroused the application of integrated magnesium (Mg) alloy die casting technology in automobiles. Previously, the application of Mg alloys in automobiles, especially in automotive cockpit components, is quite extensive, while it has almost disappeared for a period of time due to its relatively high cost, causing a certain degree of information loss in the application technology of Mg alloy parts in automobiles. The rapid development of automotive technology has led to a higher requirement for the automotive components compared with those traditional one. Therefore, whatever the components themselves, or the Mg alloy materials and die casting process have to face an increasing challenge, needing to be upgraded. In addition, owing to its high integration characteristics, the application of Mg alloy die casting technology in large-sized and thin-walled automotive parts has inherent advantages and needs to be expanded urgently. Indeed, it necessitates exploring advance Mg alloys and new product structures and optimizing die casting processes. This article summarizes and analyzes the development status of thin-walled and large-sized die casting Mg alloy parts in passenger car cockpit and corresponding material selection methods, die casting processes as well as mold design techniques. Furthermore, this work will aid researchers in establishing a comprehensive understanding of the manufacture of thin-walled and large-sized die casting Mg alloy parts in automobile cockpit. It will also assist them in developing new Mg alloys with improved comprehensive performance and new processes to meet the high requirements for die casting automotive components. [ABSTRACT FROM AUTHOR]

The innovative and environmentally friendly methodologies for comprehensively enhancing the performances of high-strength steels without damage to plasticity, toughness and heat/corrosion/fatigue resistance are being developed. In recent years, nanoparticles elevate the field of high-strength steel. It is proposed that nanoparticles have the potential to replace conventional semi-coherent intermetallic compounds, carbides and alloying to optimize the steel. The fabrication process is simplified and the cost is lower compared with the traditional methods. Considerable research effort has been directed towards high-performance cast steels reinforced with nanoparticles due to potential application in major engineering. Nanoparticles are found to be capable of notably optimizing the nucleation behavior and precipitate process. The prominently optimized microstructure configuration and performances of cast steel can be acquired synchronously. In this review, the lattice matching and valence electron criterion between diverse nanoparticles and steel are summarized, and the existing various preparation methods are compared and analyzed. At present, there are four main methods to introduce nanoparticles into steel: external nanoparticle method, internal nanoparticle method, in-situ reaction method, and additive manufacturing method. These four methods have their own advantages and limitations, respectively. In this review, the synthesis, selection principle and strengthening mechanism of nanoparticles in cast steels for the above four methods are discussed in detail. Moreover, the main preparation methods and microstructure manipulation mechanism of the steel reinforced with different nanoparticles have been systematically expatiated. Finally, the development and future potential research directions of the application of nanoparticles in cast steel are prospected. [ABSTRACT FROM AUTHOR]

The nano-sized SiCp/Al-Cu composites were successfully fabricated by combining semisolid stirring with ball milling technology. Microstructures were examined by an olympus optical microscope (OM), field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). Tensile properties were studied at room temperature. The results show that the α-Al dendrites of the composites were strongly refined, especially in the composite with 3 wt. % nano-sized SiCp, of which the morphology of the α-Al changes from 200 μm dendritic crystal to 90 μm much finer equiaxial grain. The strength and ductility of the composites are improved synchronously with the addition of nano-sized SiCp particles. The as-cast 3 wt. % nano-sized SiCp/Al-Cu composite displays the best tensile properties, i.e., the yield strength, ultimate tensile strength (UTS) and fracture strain increase from 175 MPa, 310 MPa and 4.1% of the as-cast Al-Cu alloy to 220 MPa, 410 MPa and 6.3%, respectively. The significant improvement in the tensile properties of the composites is mainly due to the refinement of the α-Al dendrites, nano-sized SiCp strengthening, and good interface combination between the SiCp and Al-Cu alloys. [ABSTRACT FROM AUTHOR]

The transient gain-absorption properties of the probe field in vertical triple quantum dots assisted by double tunneling and incoherent pumping are investigated. With a proper intensity value and detuning of the second tunneling, the transient gain in triple quantum dots with incoherent pumping can be completely eliminated. In addition, the incoherent pumping affects both the amplitude of the transient absorption and the steady-state value. The dependence of transient behaviors on other parameters, such as the radiative decay rate and the pure dephasing decay rate of the quantum dots, is also discussed. The scheme may have important applications in quantum information networks and communication. [ABSTRACT FROM AUTHOR]