In the light of the property requirements to design microstructures will become an important develop direction of metal materials. Here, a new concept of microstructure tailoring is proposed. The main features of microstructure tailoring include designing mesoscale microstructure, establishing quantitative relation between microstructures and properties, accurately inverse-designing and fabricating microstructures to satisfy the property requirements. It means screening, multi-scale calculation, and quantification of the essential microstructural factors should be performed first. Second, the microstructures are purposefully fabricated after adjusting the thermodynamics and kinetics of phase transformation. Third, the microstructures are assessed and tailored through iterative optimization. Microstructure tailoring must be preceded by purification and homogenization of metals. Only when the purity problem of materials is solved first, the influence of inclusions and impurity elements can be eliminated. Only by eliminating the macro-segregation can the material achieve homogeneity. And then the intrinsic properties of the material be fully reflected. As an example of microstructure tailoring, this study investigates the expected fatigue-life requirements of M50 (G80Cr4Mo4V) steels used for bearings in aircraft engines. By controlling the macro-segregation and purification, it is found that the fatigue-life of M50 steel mainly depends on primary carbides. And then the size, type, and morphology of the primary carbides are quantitatively tailored to fulfill the fatigue-life requirement. With technological developments in the metallurgy industry, microstructure tailoring will become a mainstay of the development of metals. And, applying data science and modeling along with microstructure tailoring technology, the alloy design will be gradually optimized in the future. The expensive metal addition will be reduced gradually, so as to save resources and develop green materials.

Tianwen-1 is China's first planetary probe. Its core, the rover Zhurong, undertook the task of tour and survey, and had extended the mission over the designed 90-Martian-day period limit on Mars. The rover was equipped with various silicon-carbide-particle-reinforced aluminum matrix composites for its bearing structure, motion system, and detectors to meet design requirements, such as lightweight, wear resistance, impact resistance, and dimensional stability. The use of these composites has set a new record for the proportion of aluminum matrix composites used in Chinese spacecraft. This paper discusses the research and development process of the four types of aluminum matrix composites used for the rover Zhurong: property simulation, material design, preparation, and processing. Additionally, the paper introduces new research and development paradigms based on material genetic engineering and the use of synchrotron radiation or neutron scattering facilities. The future development of aluminum matrix composites for high-tech equipment is also discussed.

Stacking fault energy (SFE) can play a crucial role in plastic deformation and damage mechanisms of face-centered cubic (fcc) metals. This study mainly summarized the following results: (1) With the reduction of SFE, the slip mode of fcc metals gradually changes from a facile cross-slip wavy mode to a planar mode until deformation twinning occurs; (2) The concept of effective SFE is applied to investigate the variation of SFE with dislocation density in the fcc metals, with the increase in dislocation density, the effective SFE increases; (3) The reduction of SFE is not the only factor determining the formation of deformation twins in fcc metals. In terms of calculating the competition between simulated slipping and twinning using the first principles, the critical criterion for forming deformation twinning in fcc metals was established; (4) The fatigue dislocation configuration of high-, medium-, and low-SFE fcc metals were analyzed and the judgment conditions for forming regular persistent slip bands (PSBs) are proposed; (5) With the increase in Al content, the SFE of Cu-Al alloy decreases, resulting in a simultaneous increasing trend in the tensile strength and the uniform elongation due to the increasing planar slip degree; (6) The exponential strain-hardening model can accurately describe the tensile strain-hardening process of Cu-Al alloys. The quantitative relationship among yield strength, tensile strength, and uniform elongation of Cu-Al alloy with different alloy compositions and microstructure states was successfully predicted; (7) With the increase in Al content, the fatigue strength of Cu-Al alloy is improved. Increasing Al content at the same strain amplitude will enhance its low-cycle fatigue life. Based on the experimental results above, it is shown that the alloy composition affects the deformation and damage mechanisms, and the evolution process of microscopic defects (dislocations, twins) in fcc metals and alloys. Thus, it drastically affects the tensile and fatigue properties of the fcc metals and alloys. These results provide experimental evidence and a theoretical basis for improving the mechanical properties and service reliability of fcc metals and alloys via alloy designing.

Porous titanium alloys have been used for biomedical implants owing to their low-modulus matching with that of human bones and interconnecting pores with suitable size, which facilitates bone in-growth and satisfies the requirement of a successful implant. Recently, additive manufacturing (3D printing) has emerged as an excellent technology for manufacturing porous implants with accurate designed pore parameters and overcoming processing difficulties caused by high melting temperatures of metals. In this paper, the microstructure and mechanical properties of porous Ti-6Al-4V, commercial pure titanium (CP-Ti), and low-modulus Ti2448 alloys produced by 3D printing, obtained mainly by the authors' group, are reviewed. For Ti-6Al-4V, its fatigue properties are affected by the type of mesh struts and post processing. The better fatigue life of CP-Ti compared to that of Ti-6Al-4V derives from its superior ductility and the strain hardening effect caused by deformation twins. The excellent fatigue life of the low-modulus Ti2448 alloy results from its superelasticity and the high toughness, which increases the crack nucleation life and fatigue crack propagation life, respectively. Future directions of corrosion-fatigue properties of materials in complex physiological environments, surface biological functionalization, and porous material of new metallic alloy systems are discussed.

This article reviews recent advances in the exact solution of ferromagnetic three-dimensional (3D) Ising model. First, the topological quantum statistic mechanism was introduced, which includes the time average, Jordan-von Neumann-Wigner framework, and the contribution of topological structures to thermodynamic properties of the system. Then, the Clifford algebra approach and the method of the Riemann-Hilbert problem were introduced to prove Zhang's two conjectures for the exact solution of the ferromagnetic 3D Ising model. The proof process verifies the correctness of the Zhang's exact solution for the ferromagnetic 3D Ising model. Based on these progresses, the origin of time was investigated and driven to the conclusion that in 3D many-body interacting particle (or spin) systems, time emerges spontaneously from many-body interactions.

Structural materials are one of the major factors that restrict the lead-cooled fast reactor construction due to metallic elements that can dissolve in the liquid lead-bismuth eutectic (LBE), which may affect the structure's safety. T91 steel and 316 stainless steel are the leading structural materials for critical equipment such as fuel cladding, reactor vessels, and reactor core internals. The environmental compatibility of those steels with the liquid LBE needs to be systematically evaluated. However, T91 steel and 316 stainless steel suffer from rapid oxidation corrosion in oxygen-saturated LBE at 550^oC. T91 steel's corrosion resistance in liquid LBE can be improved by decreasing the oxygen concentration (1.26 × 10^-6%, mass fraction), but dissolved corrosion occurred at dissolved oxygen concentration below 1 × 10^-6% for T91 steel and 316 stainless steel. T91 steel is sensitive to liquid metal embrittlement, significantly reducing its corrosion fatigue life in the liquid LBE. Compared to the standard (9%-12%)Cr ferritic/martensitic steel and 316 stainless steel, the microalloyed Si enhanced (9%-12%)Cr ferritic/martensitic steel (9Cr-Si and 12Cr-Si) and 316 stainless steel (ASS-Si) have good microstructural stability and comprehensive mechanical properties. The Si-rich oxide formation in liquid LBE improves the oxide film compactness and corrosion resistance. The dissolution corrosion was inhibited in static oxygen-saturation and oxygen-controlled (10^-6%-10^-7%) flowing liquid LBE (0.3 m/s) at 550^oC for 9Cr-Si, 12Cr-Si, and ASS-Si. These alloys are expected to meet the design requirements for a lead-cooled fast reactor.

Global nuclear power events are often caused by local corrosion, which starts at the surface. The effect of the surface state on corrosion and the interaction among corrosion, irradiation, and stress are important technical problems affecting the safety, reliability, and economy of nuclear power plants. In this paper, supported by a series of national projects in the last 10 years, the various surface state effects, for key structural materials used in nuclear power plants after surface finishing, grinding, machining, or scratching, on corrosion and stress corrosion behaviors in the simulated primary water of nuclear power plants are reviewed. The results show that surface grinding, scratching, or cutting can cause the formation of microstructures of different gradients near the surface and also cause large differences in surface deformation. For example, the residual compressive stress is greater than the yield stress in the superficial surface of the scratch; the different cutting parameters can cause the various gradient structures of the nanocrystalline and grain distortion zones to form along the depth of the cutting surface with similar surface roughness. Such microstructures and local stress-strain conditions lead to significant differences in corrosion resistance. For example, the number of stress corrosion cracks is positively correlated with scratch depth. Under the combined action of irradiation, corrosion, and stress, irradiation-assisted stress corrosion is further enhanced. Finally, the future research trend on the topic is forecast.

High thrust-to-weight ratios and high propulsion are necessary requirements for revolutionizing the aviation technology. Emerging hot-section engine components are currently focused on SiC_f/SiC ceramic matrix composite materials, wherein the environmental barrier coatings (EBCs) are needed to protect the engine components from the harsh combustion environment. Due to their matched thermal expansion coefficient and good chemical compatibility with the SiC_f/SiC ceramic matrix composites substrates, rare earth (RE) silicates have been identified as promising EBC materials. However, they cannot provide reliable protection for the engine components when the working temperature rises over 1300^oC, mainly because of their poor resistance to the low melting point oxides CaO-MgO-Al₂O₃-SiO₂ (CMAS) melts. This review discusses the current state of research on the CMAS corrosion resistance of RE silicates. First, the interaction and degradation mechanisms of single-RE-component RE₂SiO₅ and RE₂Si₂O₇ are discussed, and the different roles of RE species in reacting with CMAS melts are summarized. Then, the concept of high-entropy design is introduced, enabling synergistic optimization of the effects of multiple RE species in terms of CMAS resistance, by delicately designing the multi-RE-component (nRE _x ) compositions. Such a strategy leads to enhanced CMAS corrosion resistance in some novel (nRE _x )₂SiO₅ and (nRE _x )₂Si₂O₇ materials. Finally, potential prospects, opportunities, and challenges for high-entropy RE silicates as EBC materials are discussed.

Owing to low spraying temperature and high particle velocity, cold spray is a rapidly developing solid-material deposition technology that has broad application prospects in areas of metal coating preparation, additive manufacturing, and component repair. The Institute of Metal Research, Chinese Academy of Sciences, has conducted extensive research on cold spray, including the exploration of bonding mechanism, strategies and methods of tailoring microstructures and properties of deposits, and application of the cold spray technology. This paper systematically introduces the research progress of cold spray by the Institute of Metal Research, Chinese Academy of Sciences.

Liquid oxygen (LOX)/kerosene rocket engines are the main power system of heavy launch vehicles around the globe, and the turbine materials are usually exposed to elevated temperatures, high pressure, and oxygen-enriched environment in gas generators. Metal combustion may occur under these working conditions. GH4061 is a newly developed Ni-based superalloy that is used in turbine materials because of its excellent mechanical properties. However, its combustion resistance property has rarely been studied. Recently, several studies on metal combustion have been conducted, but they mainly focus on exploring the rules of metal combustion. Furthermore, the domestically promoted ignition-combustion (PIC) experiment equipment only supports the test under 2 MPa pressure, which has significantly limited the study of metal combustion at higher pressure. Therefore, the analysis of the metal combustion mechanism remains incomplete. In this study, the 3.5-25 MPa high pressure and oxygen-enriched combustion experiments of GH4061 alloy were performed on the basis of independently-developed PIC equipment with a maximum pressure of 25 MPa. A high-speed camera was used to observe and record the combustion process. The postcombustion microstructure was characterized using SEM and EDS, and the combustion product was identified using XRD. The length and rate of burning increase as the oxygen pressure increases. The critical burning pressure of GH4061 under 99.5% oxygen (when igniting at 25^oC) is about 5 MPa, according to ASTM-G124. After testing, the transition zone, melting zone, ignition interface, and oxide zone in the samples were characterized. The burning process is due to elements with a higher heat of combustion. During combustion, lower-density molten oxides float up to the melting zone. After testing, small O/Al/Ti-rich particles and large complex oxide particles with dendritic morphology were observed in the melting zone. The effect of oxygen pressure was analyzed using thermodynamics.

The effect of long-period stacking ordered (LPSO) structure/solute-rich element laminar stacking faults (SFs) on the intersection of co-zone {\mathrm{10}\overline{\mathrm{1}}\mathrm{2}} twin variants was uncovered at the atomic scale by TEM. The results show that a basal-prismatic (BP) boundary is generally formed at the intersection of LPSO/SFs and twins, bending the twin boundaries (TBs) into a bow shape between the adjacent LPSO/SFs. The co-zone {\mathrm{10}\overline{\mathrm{1}}\mathrm{2}} twin variants and LPSO/SFs intersect with each other, introducing a basal-basal (BB) boundary and prismatic-prismatic (PP) boundaries, associated with a triangular matrix near the LPSO/SFs. More Zn atoms than Y atoms were segregated into the TBs. Also, when the LPSO structure is kinked, the {\mathrm{10}\overline{\mathrm{1}}\mathrm{2}} twin generates and grows on one side of the kink boundary, and the local kink boundary transforms into TB. The growing TB intersects with the residual kink boundary, leaving a triangular matrix near the LPSO/SFs. Multiple twin variants nucleate between the LPSO/SFs/TSFs (twinned stacking faults), and the associated Hall-Petch effect is brought by the segmentation introduced by the intersecting of variants, which can improve the Mg alloy hardening rate. Introducing different twin variants by regulating the LPSO structure's spacing and thickness in magnesium alloy may shed new light on optimizing their performance.

Laminated metals have the potential for achieving better mechanical properties, such as higher strength, ductility, and work hardening ability. The mechanism that leads to these advances stems from the inhomogeneous plastic deformations between soft and hard components where geometrically necessary dislocations (GNDs) are produced while the two adjacent components are mutually constrained. Many structural factors have already been extensively investigated during the optimization of the laminated structure, such as the effect of layer thickness and the strength differential between components on the overall resulting properties. However, the effect of component composition percentage, an important factor for laminated structures, on the mechanical properties and its underlying mechanism remains elusive. To unravel the effect of component composition percentage on the mechanical properties, we used stable nanotwinned structures as components to build laminated nanotwinned (LNT) Cu materials. Three LNT Cu samples with hard components on the surface layers and soft components in the core layer were designed and prepared by direct-current electrodeposition. The soft component percentages were set as 10%, 50%, and 90%. The mechanical behaviors of LNT Cu were explored by uniaxial tensile tests at room temperature. Yield strengths for all three LNT Cu were higher than that estimated by the rule of mixture, indicating an extra strengthening effect from the LNT structure. The LNT Cu containing 50% soft component (LNT-50%) demonstrated the greatest extra strengthening. Interestingly, full-field strain measurements and microstructure characterizations further indicated that the strain localization of LNT-50% was well suppressed and the lateral strain difference between the soft and hard components was obviously reduced. This indicated that the strong mutual constraint between the two components contributed to the greatest extra strengthening.

Ni-Ti alloys are used widely as a self-expanding vascular stent material because of their unique shape memory effect and superelasticity. However, after implantation, there is a risk of in-stent restenosis (ISR) because of insufficient endothelialization and coagulation problems. As a biological functional metal element, the proper addition of Cu endows vascular stent materials, such as stainless steel and cobalt-based alloys, with significant endothelialization promotion and anticoagulant effect, which can effectively inhibit the occurrence of ISR. Based on the alloying strategy, a biofunctional Ni-Ti-Cu alloy was prepared by adding the proper amount of Cu into medical Ni-Ti alloys. The inhibition effect of ISR and corrosion resistance of the Ni-Ti-Cu alloy were studied via OM, SEM, XRD, surface free energy test, electrochemical test, and in vitro cell experiment. Results showed that compared with the Ni-Ti alloy, the Ni-Ti-Cu alloy promoted the transformation of an equiaxed austenite grain structure to fine lath martensite, reduced the surface free energy, and improved corrosion resistance in simulated human blood. In addition, the extract of the Ni-Ti-Cu alloy could promote the proliferation, migration, and tube formation of human umbilical vein endothelial cells. Furthermore, compared with the Ni-Ti alloy, the Ni-Ti-Cu alloy decreased the blood coagulation rate, presenting better anticoagulation ability, which has an application potential for inhibiting the occurrence of ISR.