Thin-walled and large-sized magnesium alloy die castings for passenger car cockpit:Application,materials,and manufacture

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.

Ceramic particles reinforced copper matrix composites manufactured by advanced powder metallurgy:preparation, performance, and mechanisms

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.

Application of nanoparticles in cast steel:An overview

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.

Metallurgy and Solidification Microstructure Control of Fusion-Based Additive Manufacturing Fabricated Metallic Alloys:A Review

The metal-based additive manufacturing(AM),also referred to as metal 3D printing,has drawn particular interest because it enables direct creation,aided by computationally-directed path design,of intricate components with site-specific compositions and geometrical requirements as well as low buy-to-fly ratios.During the last two decades,the objective of this revolutionary technology has been shifting from only“rapid prototyping”to advanced manufacturing of special high-end products or devices,which,in many aspects,outperform conventional manufacturing technologies.For fusion-based AM,significant progress has been achieved in understanding the processing window of macroscopic scales,non-equilibrium metallurgy of mesoscale scales,and grain evolution of microscopic scales.Although the versatile capacity of AM facilitates new avenues for discovering advanced materials and structures,their potential has still not been fully explored.Given the unique non-equilibrium solidification during the AM process,coarse columnar grains with strong textures are usually developed along the build direction,which downgrades the mechanical performance.To push the limits of this digital manufacturing,this review attempts to provide in-depth and comprehensive overviews of the recent progress in understanding the evolution and control of the as-built microstructure that has been made recently and the challenges encountered during the AM process.

Extracting more light for vertical emission:high power continuous wave operation of 1.3-μm quantum-dot photonic-crystal surface-emitting laser based on a flat band

For long distance optical interconnects,1.3-μm surface-emitting lasers are key devices.However,the low output power of several milliwatts limits their application.In this study,by introducing a two-dimensional photonic-crystal and using InAs quantum dots as active materials,a continuous-wave,13.3-mW output power,1.3-μm wavelength,room-temperature surface-emitting laser is achieved.In addition,such a device can be operated at high temperatures of up to 90℃.The enhanced output power results from the flat band structure of the photonic crystal and an extra feedback mechanism.Surface emission is realized by photonic crystal diffraction and thus the distributed Bragg reflector is eliminated.The proposed device provides a means to overcome the limitations of low-power 1.3-μm surface-emitting lasers and increase the number of applications thereof.