为提高轨道交通部件用铝合金阻尼性能以满足减振降噪需求，本文采用层状异质构型复合化的方法，利用真空热压复合及冷轧加工制备5083Al/SUS405层状复合材料。采用X射线衍射、扫描电镜、万能材料试验机、动态机械热分析仪等研究了冷轧压下率对复合材料组织性能的影响。结果表明：随冷轧压下率增加，5083Al/SUS405界面从平直状态逐渐变为波浪状，最终SUS405层出现颈缩并断裂。热压态和50%冷轧压下率的复合材料抗拉强度分别比5083Al提高了28%和45%，热压态伸长率提高了46%；冷轧压下率升至75%时，抗拉强度和伸长率均降低。热压态复合材料在整个应变振幅范围内的阻尼性能优于冷轧态及5083Al；冷轧态复合材料在应变振幅高于第二临界应变时（微塑性变形阶段），阻尼随应变振幅迅速上升，高于5083Al。

The laminated heterostructure composite design was implemented on 5083Al alloy. Through the process of vacuum hot pressing (HP state) followed by cold rolling and annealing (CRA state), the 5083Al/SUS405 laminated heterostructure composites (LHCs) were fabricated. The LHCs exhibit excellent combination of strength-ductility and damping capacity. The damping in the LHCs originates from the combined effects of dislocation, interface and ferromagnetic damping mechanisms. Compared to 5083Al alloy, the LHCs exhibit higher dislocation damping at relatively high strain amplitudes (Ε > 0.01 %), especially for the CRA state LHC with higher density of geometrically necessary dislocations (GNDs). This suggests that GNDs not only enhance strength-ductility through the hetero-deformation induced (HDI) hardening effect, but also contribute to dislocation damping in the LHCs. © 2023 Elsevier B.V.

In order to evaluate the difference in the effects of Al and Ti elements on the microstructure and tribological behaviors of CoCrFeNi-based high entropy alloy (HEA) coatings, CoCrFeNiSi0.5-(Al,Ti) non-equiatomic HEAs coatings were prepared using direct laser deposition (DLD). The phase constitution, solidification microstructure and tribological behaviors of the HEA coatings were investigated. The results indicated that CoCrFeNiSi0.5 HEA coating was composed of face centered cubic (FCC) phase with microstructure of columnar and cellular grains. The addition of Al and Ti led to a columnar-to-equiaxed transition (CET) in the HEA coatings. When only Al was added (CoCrFeNiSi0.5Al0.5), the primary phase transformed into a body centered cubic (BCC) phase (94 vol%). Additionally, Cr3Si formed in the interdendrite (ID) region, and a spinodal decomposition structure emerged in the dendrite (DR) region. Conversely, with the inclusion of Ti alone (CoCrFeNiSi0.5Ti0.5), the matrix maintained its FCC phase, but Ni16Ti6Si7 (G phase, 20.9 vol%) and Cr15Co9Si6 (15.1 vol%) were generated in the ID and DR regions, respectively. Incorporating both Al and Ti (CoCrFeNiSi0.5Al0.5Ti0.5) significantly reduced the G phase content in the ID region to 7.9 vol% and led to the formation of dispersed Fe3Al nanoparticles with an average size of 99 nm in the DR region. The CoCrFeNiSi0.5 HEA coating exhibited the lowest hardness (249 HV0.1), the highest friction coefficient (0.778), and the poorest wear resistance. For the HEA coatings containing Al and Ti, the microhardness significantly increased to over 700 HV0.1, and the friction coefficient decreased to around 0.6. However, the wear resistance of the CoCrFeNiSi0.5Al0.5 HEA coating was almost equivalent to that of the CoCrFeNiSi0.5 with a wear loss of 5.1 mg. By contrast, the HEA coatings containing Ti demonstrated notably improved wear resistance, with wear losses of only 2.2 mg and 2.4 mg for the CoCrFeNiSi0.5Ti0.5 and CoCrFeNiSi0.5Al0.5Ti0.5 HEA coatings, respectively. © 2024 Elsevier B.V.

通过真空热压复合、冷轧及热处理的方式制备了具有不同层间硬度比（分别为3.0， 5.0， 7.0）的Cu-Be/Cu层状异构复合材料。研究了层间硬度比对复合材料强度-塑性匹配及应变硬化率的影响，探索了不同层间硬度比下异质变形诱导强化对复合材料应变硬化行为的影响。研究结果表明，随层间硬度比的升高，层状异构复合材料的抗拉强度升高、均匀伸长率降低，但复合材料抗拉强度均高于依据混合定律计算值，且均匀伸长率均高于相应Cu-Be组元，其中硬度比为5.0的复合材料具有最优强度-塑性匹配。异质变形诱导强化作用可使层状异构复合材料中产生额外应变硬化，但硬度比为3.0的复合材料中异质变形诱导强化产生的应变硬化作用较弱，而硬度比为7.0的复合材料中异质变形诱导硬化作用在塑性变形初期就达到饱和状态并迅速降低，硬度比为5.0的复合材料中异质变形诱导硬化在材料应变硬化过程中占据主导作用，且可在较大应变范围内为材料提供额外应变硬化能力。

The laser deposited CoCrFeNi based high entropy alloy (HEA) coatings can possess better corrosion resistance than the austenitic and ferritic stainless steels, and are expected to be applied to the anticorrosive coating on the materials serving in the harsh environment, such as marine industry, petrochemical industry, aerospace, etc. As two commonly used elements for improving the corrosion resistance of CoCrFeNi based HEA coatings, the individual effect of Al or Ti element on the corrosion resistance of CoCrFeNi based HEA coatings has been well studied, but it is still lack of the research aiming at comparing which of these two elements has more significant effect on the coatings. This work aims to compare the effects of Al and Ti element on the corrosion behaviors of non-equiatomic CoCrFeNiSi-(Al,Ti) HEA coatings. The CoCrFeNi HEA, Al, Si, and Ti powder were used to prepare the mixture powder according to the composition of CoCrFeNiSi0.5, CoCrFeNiSi0.5Al0.5, CoCrFeNiSi0.5Ti0.5, and CoCrFeNiSi0.5Al0.5Ti0.5. The HEA coatings were prepared by a semiconductor laser (LDM-2500-60) with coaxial powder feeding method on the 316L substrates. The phase structure of the laser deposited coatings was analyzed by an X-ray diffractometer (XRD, D8 Advance, Bruker). The microstructure of the longitudinal section (plane perpendicular to the laser scanning direction) of the coatings was observed by an optical microscope (OM, Axio Vert.A1, Zeiss). The microstructure of the surface of the coatings before and after corrosion was studied by a field emission scanning electron microscope (FESEM, SU-8010, Hitachi), while the micro-area composition was analyzed by the supporting energy dispersive spectroscopy (EDS). The corrosion behaviors of the HEA coatings in 0.5 mol/L H2SO4 solution were studied by an electrochemical workstation (CS350, Wuhan Corrtest). The results indicated that the laser deposited CoCrFeNiSi0.5 HEA coatings were composed of face-centered cubic (FCC) phase. The major phase of CoCrFeNiSi0.5Al0.5 HEA coatings changed to body-centered cubic (BCC) phase and the Cr3Si phase distributed along the grain boundaries was established. The major phase of CoCrFeNiSi0.5Ti0.5 HEA coatings maintained FCC phase, but a large quantity of G phase (Ni16Ti6Si7) was formed in the interdendritic (ID) region and the long-strip Cr15Co9Si6 phase was formed in the dendritic (DR) region. The major phase of CoCrFeNiSi0.5Al0.5Ti0.5 HEA coatings was BCC phase and the content of G phase distributed in the ID region was much lower than that in CoCrFeNiSi0.5Ti0.5 HEA coatings. Furthermore, a large number of dispersed square nanoparticles were formed in the DR region. The corrosion resistance of laser deposited non-equiatomic CoCrFeNiSi-(Al,Ti) HEA coatings in 0.5 mol/L H2SO4 solution could be ordered as CoCrFeNiSi0.5Ti0.5> CoCrFeNiSi0.5Al0.5Ti0.5>CoCrFeNiSi0.5>CoCrFeNiSi0.5Al0.5. After immersion in the 0.5 mol/L H2SO4 solution, the CoCrFeNiSi0.5 HEA coatings exhibited relatively uniform corrosion and the CoCrFeNiSi0.5Al0.5 HEA coatings indicated severely intergranular corrosion. CoCrFeNiSi0.5Ti0.5 and CoCrFeNiSi0.5Al0.5Ti0.5 HEA coatings mainly presented pitting corrosion in the ID region, while the latter had a higher extent of pitting corrosion and the nanoparticles in the DR region fell off. In general, compared with Al element, Ti element can improve the corrosion resistance of laser deposited CoCrFeNi based HEA coatings more effectively in acidic solution environment, due to the better protective effect produced by the passivation film. This work can provide theoretical references and data supports for the research and development of HEA anticorrosive coatings serving in the harsh environment. © 2023 Chongqing Wujiu Periodicals Press. All rights reserved.

With the development of high-speed and heavy-haul railway transportation, the surface failure of rail turnouts has become increasingly severe due to insufficient high hardness-toughness combination. In this work, in situ bainite steel matrix composites with WC primary reinforcement were fabricated via direct laser deposition (DLD). With the increased primary reinforcement content, the adaptive adjustments of the matrix microstructure and in situ reinforcement were obtained at the same time. Furthermore, the dependence of the adaptive adjustment of the composite microstructure on the composites' balance of hardness and impact toughness was evaluated. During DLD, the laser induces an interaction among the primary composite powders, which leads to obvious changes in the phase composition and morphology of the composites. With the increased WC primary reinforcement content, the dominant sheaves of the lath-like bainite and the few island-like retained austenite are changed into needle-like lower bainite and plenty of block-like retained austenite in the matrix, and the final reinforcement of Fe3W3C and WC is obtained. In addition, with the increased primary reinforcement content, the microhardness of the bainite steel matrix composites increases remarkably, but the impact toughness decreases. However, compared with conventional metal matrix composites, the in situ bainite steel matrix composites manufactured via DLD possess a much better hardness-toughness balance, which can be attributed to the adaptive adjustment of the matrix microstructure. This work provides a new insight into obtaining new materials with a good combination of hardness and toughness.

将层状非均质构型复合化设计思想用于提高Cu-Be合金强韧性,采用真空热压复合、热轧及热处理的方式制备了CuBe/Cu层状非均质复合材料。对复合材料显微组织、显微硬度及拉伸性能进行了测试分析,利用SEM下原位拉伸结合DIC技术,研究了复合