Strain-Controlled Thermal-Mechanical Fatigue Behavior and Microstructural Evolution Mechanism of the Novel Cr-Mo-V Hot-Work Die Steel.

In response to the intensifying competition in the mold market and the increasingly stringent specifications of die forgings, the existing 55NiCrMoV7 (MES 1 steel) material can no longer meet the elevated demands of customers. Consequently, this study systematically optimizes the alloy composition of MES 1 steel by precisely adjusting the molybdenum (Mo) and vanadium (V) contents. The primary objective is to significantly enhance the microstructure and thermal-mechanical fatigue performance of the steel, thereby developing a high-performance, long-life hot working die steel designated as MES 2 steel.

Study on High-Temperature Constitutive Model and Plasticity of the Novel Cr-Mo-V Hot-Work Die Steel Forging.

In response to the increasingly strict performance requirements of large molds, a novel Cr-Mo-V hot-work die steel has been developed. In order to study the high-temperature hot deformation behavior and plasticity of the novel steel, hot compression tests were conducted on the Gleeble-1500D thermal simulation testing machine at a deformation temperature of 950~1200 °C and a strain rate of 0.001~5 s.

Effect of AlCu constituent layer thickness discrepancy on the tensile mechanical behavior of Cu/AlCu/Al layered composites: a molecular dynamics simulation.

Nano-polycrystalline Cu/AlCu/Al layered composites with different layer thicknessesof single-crystal AlCu constituent are constructed. The effects ofon the strength and fracture modes of nano-polycrystalline Cu/AlCu/Al layered composites are systematically investigated by molecular dynamics simulations. The uniaxial tensile results show that the ultimate strength and fracture mode of the nano-polycrystalline Cu/AlCu/Al layered composites do not change monotonically with the change of single crystal AlCu constituent layer thickness, the ultimate strength peaking at= 2.

Molecular Dynamics Study of Interfacial Micromechanical Behaviors of 6H-SiC/Al Composites under Uniaxial Tensile Deformation.

This paper investigated the micromechanical behavior of different 6H-SiC/Al systems during the uniaxial tensile loading by using molecular dynamics simulations. The results showed that the interface models responded diversely to the tensile stress when the four low-index surfaces of the Al were used as the variables of the joint surfaces. In terms of their stress-strain properties, the SiC(0001)/Al(001) models exhibited the highest tensile strength and the smallest elongation, while the other models produced certain deformations to relieve the excessive strain, thus increasing the elongation.

Low-dimensional transition metal sulfide-based electrocatalysts for water electrolysis: overview and perspectives.

Hydrogen prepared by electrocatalytic decomposition of water ("green hydrogen") has the advantages of high energy density and being clean and pollution-free, which is an important energy carrier to face the problems of the energy crisis and environmental pollution. However, the most used commercial electrocatalysts are based on expensive and scarce precious metals and their alloy materials, which seriously restricts the large-scale industrial application of hydrogen energy. The development of efficient non-precious metal electrocatalysts is the key to achieving the sustainable development of the hydrogen energy industry.

Numerical Simulation of Copper-Aluminum Composite Plate Casting and Rolling Process and Composite Mechanism.

This paper uses ANSYS Workbench platform to simulate the casting and rolling composite process, taking the horizontal type casting and rolling machine as the research object, and conducts the numerical simulation study of copper-aluminum composite solid-liquid casting and rolling heat-flow coupling, mainly to study different walking speed, aluminum pouring temperature, casting and rolling zone length, heat transfer coefficient on the temperature field, liquid phase rate influence law, and use it as a theoretical guide for copper-aluminum solid-liquid casting. The experiments of copper-aluminum solid-liquid casting-rolling composite were carried out to optimize the process parameters and to verify the experiments, so as to prepare a well-bonded copper-aluminum composite plate. The composite mechanism in the preparation of copper-aluminum composite plate was analyzed, and it was clarified that the interfacial layer was formed through four stages: contact between copper and aluminum surfaces, contact surface activation, mutual diffusion of copper and aluminum atoms, and reaction diffusion.

Effect of Secondary-Phase Precipitation on Mechanical Properties and Corrosion Resistance of 00Cr27Ni7Mo5N Hyper-Duplex Stainless Steel during Solution Treatment.

In this work, the effect of secondary-phase precipitation on the microstructure, mechanical properties, and corrosion resistance of 00Cr27Ni7Mo5N hyper-duplex stainless steel (HDSS) during solution treatment was investigated. The results reveal that σ-phase precipitates at the interface between the α and γ phase when the solution treatment temperature is lower than 1070 °C. It is not only brittle, but also prone to create a Cr-depleted zone, which significantly deteriorates the mechanical properties and corrosion resistance.

Investigation on the In Situ TiAlC/TiAl Composite with a Homogenous Architecture by Adding Graphene Nanosheets.

The TiAlC/TiAl composite with a homogenous architecture was fabricated via spark plasma sintering (SPS) using Ti/Al/GNSs composite powders, after ultrasonic mechanical stirring, as raw materials. The phases, microstructure, compressive properties and Vickers hardness of the composite were methodically characterized. We observed the transformation of graphene nanosheets from multi-layer to few-layer by the ultrasonic dispersion and the uniform distribution of few-layer graphene nanosheets in composite powders by ultrasonic mechanical stirring.

Effect of CeO Content on Microstructure and Properties of SiCp/Al-Si Composites Prepared by Powder Metallurgy.

The effect of CeO content on the microstructure and properties of SiCp/Al-Si composites prepared by powder metallurgy was studied, and the mechanism of CeO in composites was deeply analyzed. The results show that the addition of the appropriate amount of CeO can refine the Si particles and improve the tensile properties of the SiCp/Al-Si composites. As the CeO content increases from 0 to 0.

Effects of Transition Element Additions on the Interfacial Interaction and Electronic Structure of Al(111)/6H-SiC(0001) Interface: A First-Principles Study.

In this work, the effects of 20 transition element additions on the interfacial adhesion energy and electronic structure of Al(111)/6H-SiC(0001) interfaces have been studied by the first-principles method. For pristine Al(111)/6H-SiC(0001) interfaces, both Si-terminated and C-terminated interfaces have covalent bond characteristics. The C-terminated interface has higher binding energy, which is mainly due to the stronger covalent bond formed by the larger charge transfer between C and Al.

Effects of CeO Content on Friction and Wear Properties of SiCp/Al-Si Composite Prepared by Powder Metallurgy.

SiCp/Al-Si composites with different CeO contents were prepared by a powder metallurgy method. The effect of CeO content on mechanical properties, friction and wear properties of the composites was studied. The results show that with the increase in CeO content from 0 to 1.

Effects of CeO on the Si Precipitation Mechanism of SiCp/Al-Si Composite Prepared by Powder Metallurgy.

SiCp/Al-Si composites with different CeO contents were prepared by a powder metallurgy method. The effect of CeO content on the microstructure of the composites was studied. The mechanism of CeO on the precipitation of Si during sintering was analyzed by theoretical calculations.

Hot-Deformation Behavior and Microstructure Evolution of the Dual-Scale SiCp/A356 Composites Based on Optimal Hot-Processing Parameters.

Hot deformation at elevated temperature is essential to densify particle-reinforced aluminum matrix composites (AMCs) and improve their performance. However, hot deformation behavior of the AMCs is sensitive to the variation of hot-processing parameters. In this paper, optimal processing parameters of dual-scale SiCp/A356 composites were determined to explore the control strategy of the microstructure.

Hot Deformation Behavior and Strain-Compensated Constitutive Equation of Nano-Sized SiC Particle-Reinforced Al-Si Matrix Composites.

The hot deformation behavior of nano-SiCp/Al-Si composites was studied by isothermal compression tests at 470-530 °C and strain rates of 0.01-5 s. A strain-compensation constitutive model was developed with a Z parameter and an Arrhenius function, and its accuracy was verified by error analysis.

Effects of Heating Mode and Temperature on the Microstructures, Electrical and Optical Properties of Molybdenum Thin Films.

In this paper, molybdenum (Mo) thin films are deposited on soda-lime glass (SLG) substrates by direct current magnetron sputtering and heated in three different modes at different temperatures, including substrate heating, annealing treatment, and both substrate heating and annealing treatment. The effects of heating temperature and heating mode on the structures, morphology, optical and electrical properties of Mo thin films were systematically investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM), atomic force microscope (AFM) and UV-visible spectrophotometer (UV-vis spectra). It is shown that as the substrate and annealing temperature increase, the crystallinity of Mo thin films is improved, and the grain sizes become bigger.