Usually，the initial microstructure of hot-rolled and quenched medium-manganese experimental steel is composed of lath martensite matrix and a small amount of tiny granular austenite， also existing apparent Mn-segregation bands. Using double intercritical annealing （holding 60 min at 750 ℃ followed by 60 min at 700 ℃）， austenite reversion transformation in Mn-rich and Mn-lean regions are modulated by stages， which efficiently promoting the refinement of retained austenite grains and the optimization of mechanical stability distribution without apparent variation of volume fraction of retained austenite. The results show that adequate and sustained strain-induced martensite transformation is favored and boosted during uni-axial tensile deformation. Due to synergistic toughening of transformation and twinning induced plasticity effects， excellent combination of strength and ductility， such as the ultra-high total elongation of 85.3% and product of strength and plasticity （PSE） of 73.4 GPa∙% are obtained eventually.

This paper focuses on the problems of uncoordinated microstructure in each layer and difficult control of interfacial microstructure during the hot roll-bonding process of 316L stainless steel and Q370qE carbon steel. The influence of the final rolling temperature on the microstructure and properties of the stainless steel clad plate is investigated. The microstructure of the clad plate is analyzed by metallographic microscope， scanning electron microscope， transmission electron microscope， and energy dispersive spectrometer. The mechanical properties are performed based on the interface tension-shear and tensile tests. The results show that the higher the final rolling temperature， the larger the thickness of the decarburization layer and carburization layer in the interface area of the clad plate， while the diffusion distance of Cr and Ni elements first increases and then decreases. When the final rolling temperature is 840 ℃， the carbon steel layer is composed of proeutectoid ferrite， bainite， and sorbite， and the stainless steel layer is composed of austenite with several fine recrystallized grains. The thickness of the decarburization layer is 40 μm， and the thickness of the carburization layer is 35 μm. With the increase of the final rolling temperature， the interface tension-shear strength of the clad plate first increases and then decreases， while the yield strength and tensile strength both increase， and the increase rate slows down at high temperatures. The tension-shear fracture position of the clad plate is located in the decarburization layer of the carbon steel， and the fracture morphology of tensile shows interface delamination. Therefore， the clad plate final rolled at 840 ℃ achieves the best mechanical performance， with the interface tension-shear strength of 339 MPa， the yield strength of 497 MPa， the tensile strength of 594 MPa， and the elongation after fracture of 18.6%， respectively.

At room temperature， the predominant plastic deformation mechanisms in industrial pure titanium TA2 encompass dislocation slip， twinning， and interfacial interactions. This study combines mechanical analysis performed during roll-forming experiments and utilizes electron backscatter diffraction and optical microscopy to investigate the microscale deformation mechanisms on both the inner and outer surfaces of TA2 sheets during roll forming from 0° to 30°.The research results demonstrate that during the forming process， as the bending angle reaches 20°， a differential stress is exerted on the axis of the hexagonal close-packed structure on the inner and outer sides. On the inner side， the plastic deformation mechanism shifts from the previously dominant pyramidal slip and basal slip to mainly ｛1012｝ tension twinning， which is due to the distinct stress acting on the axis. On the outer side， where the axis is under compressive stress， dislocation slip remains the primary deformation mechanism because the occurrence of ｛1122｝ compression twinning is hindered by its high critical resolved shear stress and the fine-grained nature of the material. As a result， ｛1122｝ compression twinning functions as an auxiliary deformation mechanism on the outer side. These findings offer critical insights into the plastic deformation behavior of TA2 during the roll-forming process.

The ship's anchor chain rings， sliding bearings， and other components exposed to seawater are subjected to long-term corrosion and wear， collectively referred to as tribocorrosion. The tricoborrosion resistance of these materials directly affects the operational safety of marine equipment. In this study， the in-situ electrochemical testing method for corrosion and wear are employed to investigate the tribocorrosion resistance of six commonly used materials in artificial seawater environments： anchor chain steel （CM690）， bearing steel （GCr15）， high-strength marine steel （AH36 steel）， cast iron for diesel engine cylinder liners （HT350）， tin bronze for plain bearing bushings （QSn8）， and steel most commonly used in mechanical structures （45 steel）. The objective is to analyze their corrosion resistance and damage resistance mechanisms. The results show that under pure corrosion conditions， QSn8 exhibits a significantly higher self-corrosion potential compared to other iron-carbon alloys， and has the lowest corrosion rate （0.09 mm/a）. However， under corrosion wear conditions， HT350 demonstrates a relatively low wear loss rate （6.28×10^-6 mm³/（N·m））， second only to QSn8 （3.47×10^-6 mm³/（N·m））. This is attributed to its high hardness and the lubricating effect of graphite flakes within the cast iron matrix. The other four materials exhibits higher wear rates，around （1.22-1.88）×10^-5 mm³/（N·m）. QSn8 shows excellent resistance to both corrosion and wear in simulated seawater conditions， making it a promising candidate for tribocorrosion-resistant components. However， its relatively high cost may limit its widespread application. If other mechanical performance requirements are met， HT350 can serve as a cost-effective alternative.

The characteristics of palladium layer on the surface of copper wire are important factors affecting the quality of free air ball （FAB） and bonding during chip packaging. In this paper， palladium-coated copper wires with different coating speeds and coating temperatures are prepared by halogen-free direct coating process. The effects of coating speed on the morphology of the coating and the characteristics of FAB are studied. The results show that with the increase of coating speed， the coating time decreases， and the uniformity of the distribution of palladium particles on the surface of the copper wire becomes worse. The agglomeration of palladium particles with uneven local distribution causes the concentration of palladium particles to be too high， and the agglomeration area of palladium particles on the surface of the coating increases. Under the plating speed of 50 m/min， the distribution of palladium on the surface of the coating is more uniform. With the increase of coating speed， the diameter of FAB decreases gradually. The difference of palladium content between the agglomeration area and the non-agglomeration area of Pd particles on the surface of Pd-coated copper wire increases， and the consistency of FAB sphere size gradually decreases. At a lower coating speed of 50 m/min， the distribution of palladium content on the surface of FAB is relatively uniform. At a higher coating speed of 100 m/min， a large number of agglomerated palladium particles on the surface of the coating are remelted to form a large area of continuous palladium-rich area on the surface of the FAB， and the uniformity of palladium redistribution is poor. Considering the uniformity of FAB size and surface palladium redistribution， the coating speed of 50 m/min and the coating temperature of 400 ℃ are the better process parameters for the coating of palladium-coated copper wire.

The C-SiC composite coating is integrally prepared on the surface of a single-crystal Si（100） substrate using chemical vapor deposition（CVD） with graphite as the extra-C source and HMDSO-H₂ as the precursor system. The surface morphology， phase composition， mechanical properties， and thermal shock resistance of the composite coatings are analyzed by scanning electron microscopy（SEM）， X-ray diffraction（XRD）， nanoindentation and scratch testing. The results show that the extra-C source enable simultaneous deposition of a carbon buffer layer and SiC coating. The prepared C-SiC composite coating exhibits a total thickness of 50 μm （including a 10 μm-thick C buffer layer）， dense structure， and excellent adhesion to the single-crystal Si substrate. The coating shows outstanding thermal shock resistance， with surface cracks emerging after 20 thermal cycles between 20 ℃ and 1200 ℃， but no warping or delamination occurs. The nanoindentation reveals that hardness and elastic modulus of the composite coating are 23.25 GPa and 272.3 GPa， respectively， while the scratch testing indicates an interfacial adhesion strength between the coating and substrate is 29 N.

The Cr coatings are fabricated on 304 stainless steel substrates using cold spray and electroplating methods. The particle deposition behavior and coating formation mechanism of Cr are clarified by analyzing the surface morphology， cross-sectional microstructure， and nanomechanical properties of the cold-sprayed Cr coatings. The results show that the electroplated Cr coating contains numerous vertical cracks， while the cold-sprayed Cr coating exhibits an irregular but compact and defect-free interface with the substrate. In addition， the surface of the cold-sprayed coating presents a large number of craters， and the near-surface region consists of fine equiaxed grains. The nanohardness in the region increases by 41.37%-62.17% compared with that of undeformed Cr particles， indicating that subsequent particles produce work hardening due to shot-peening effects upon impacting the pre-deposited coating. The hardening hinders cooperative plastic deformation between incoming particles and the existing coating， thereby reducing the feasibility of further deposition. Based on the surface morphology and the gradient distribution of nanohardness， the deposition mechanism for Cr coatings on 304 stainless steel is proposed， involving the disruption of the substrate’s oxide film， the formation of the initial coating layer， and the surface morphological evolution induced by shot-peening strengthening.

In this study，B₄C-C green containing carbon fibers are prepared by hot pressure molding process used carbon fiber，boron carbide powder，and graphite powder as raw materials，phenolic resin as molding agent，wherein，carbon fiber and powder are dispersed through shear mixing. Then B₄C composites （RBBC） are prepared by reaction sintering of B₄C-C green at 1550 ℃. The influence of carbon fiber content on the density，composition，structure，and mechanical properties of composites is studied.The results show that the RBBC has the best synthetic property when the volume fraction of carbon fiber reaches 5% in the green.The bending strength，fracture toughness，elastic modulus，and hardness reach 453 MPa，6.7 MPa·m^1/2，349 GPa，and 23.5 GPa，respectively. Carbon fiber partially reacts with silicon as a "slow-release" carbon source during the reaction sintering process，slowing down the reaction rate，avoiding material cracking and deformation during the reaction sintering process. It is also helpful for reducing the size of Si islands and content of residual Si in composites，refining the SiC grains generated by the reaction.

The baseline seal structure is widely used in the thermal protection of aircraft due to its excellent thermal insulation and stability. However， prolonged exposure to high temperatures and heavy loads in service can easily lead to permanent deformation of the seal， limiting its reusability. In this study， elastic elements woven from GH4169 alloy wires are used to fabricate ceramic fiber baseline seals with different internal filling structures， such as loose fiberfill， unidirectional fiber tow， and braided fiber bundles. The effects of the cotton core filling structure， compression cycles， and heat treatment of the elastic elements on the elastic property of the seals are investigated. The results show that as the compression level increases， the recovery ratios of the seals with the three filling structures decrease to varying degrees. When the compression level reaches 30%， the seal with the loose fiberfill structure exhibits the highest recovery ratio of 95.93%. As the number of compression cycles increases， the recovery ratio of the seal decreases. After standard heat treatment of the elastic elements， the peak load of the elastic elements at a 60% compression level decreases from 451.25 N/m （untreated） to 196.25 N/m， while the recovery ratio of the seals increases from 77.87% to 87.78%. Theoretical calculations and experimental analysis of the seal’s tightness reveal that as the pressure difference increases， the leak rate of the seal rises. The experimental values of the leak rate are higher than the theoretical values， and the tightness of the seal is influenced by its elastic property and the insulating cotton core.

3D microelectronic packaging imposes extremely stringent requirements on the size and precision of Cu core balls. To obtain Cu core balls that meet these requirements， it is essential to ensure the stability during the droplet jetting process and to precisely control the droplet size as needed. This study employs the pulsated orifice ejection method to prepare monodisperse Cu particles. The key parameters affecting particle size are determined based on the Hagen-Poiseuille law， and the relationship between these key parameters and the stability and size of Cu droplet jetting is investigated in detail. The influence of temperature and differential pressure determines whether droplets can be jetted， while the pulse waveform and the rod distance primarily control the particle size. Orthogonal experiments reveal that the particle size is co-influenced by multiple parameters， among which the voltage of the pulse waveform has the most significant impact， and the the particle size increases with the increase of the voltage. Adjusting the rod distance can regulate the stability of the jetting process. Through the analysis of the jetting window and orthogonal experiments， appropriate key parameters are selected to prepare Cu particles with target sizes of 100 μm and 200 μm. The actual obtained particle sizes are 96.27 μm and 200.69 μm， with standard deviations of approximately 2.67 μm and 2.64 μm， respectively， and sphericity values both exceeding 0.95. The prepared Cu particles exhibit uniform size and high sphericity， meeting the requirements for Cu core balls.