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The interlaminar mechanical properties of composites are important parameters for the application of laminates, and many scholars have applied carbon nanotubes (CNTs) as a promising solution to alleviate the delamination of laminates owing to its excellent mechanical properties and resin compatibility. The types of CNTs and their spatial distribution state in laminates can significantly affect the final interlaminar shear strength (ILSS) and fracture toughness of the laminates. In this paper, the methods of introducing CNTs into laminates are summarized, the techniques and methods for controlling the key parameters of CNTs such as dispersion, distribution and orientation of CNTs in laminates are reviewed. And then, these parameters of CNTs on ILSS and fracture toughness were discussed. It was found that CNTs with small diameters had more advantages in improving interlaminar mechanical properties because they easily penetrated the reinforced fabric. Moreover, CNTs distributed vertically along the thickness direction can improve the interlaminar mechanical properties of composites to a greater extent. Furthermore, through comprehensive comparison, we found that chemical vapor deposition method, interlayer insertion and surface assembly can significantly improve the mode I interlaminar fracture toughness, while the resin mixing and prepreg modification can greatly improve the mode II interlaminar fracture toughness. In addition, CNTs local filling technology can achieve the purpose of local performance improvement for composite components. Finally, the current issues and potential opportunities of the carbon fiber-reinforced laminates filled with CNTs are pointed out, and new directions for future prospects are proposed. [ABSTRACT FROM AUTHOR]

Delamination damages limit the application potential of Fiber metal laminates, hence improving the interlaminar mechanical properties has always been a research focus and challenge in this field. The toughening effect of two fillers, i.e., nano-aramid fibers (ANFs) and short-aramid fibers (ASFs), which are used at the interface of glass fiber-aluminum laminates, have been investigated. Chemical pretreatments of aluminum alloy surface were conducted to ensure the better adherence between the fiber composites and metal sheets. Results revealed that Mode-I and Mode-II fracture toughness of the laminates could be simultaneously improved when using the two fillers at the interface of glass fiber-aluminum laminates. Attributed to the better dispersion of ANFs in epoxy matrix, the toughening performance of ANFs is better than that of ASFs in this case. The mechanism of interlaminar toughening was revealed with electron microscopic observation of fracture morphology. Meanwhile, the finite element analysis based on bilinear cohesive zone model was adopted to predict the increased interlaminar tensile and shear strength. [ABSTRACT FROM AUTHOR]

Intermetallic compounds (IMCs) form at the solder/substrate interface during soldering, providing metallurgical bonding. However, cracks tend to initiate within IMCs during loading making the joint easy to fail at low shear strength. This inconvenience can be eliminated if nano-sized multi-principal-element alloy (MPEA) layers are induced to form at the interface. The nano-grained MPEAs show synergetic strength and ductility; they are able to release local stress concentration and to distribute the strain localization when the joints are subjected to shear stresses. So, the bonded CuNi/Au–Sn/CuNi joint achieves shear strength of 93 MPa. This study provides a new approach to improve the mechanical reliability of the bonded joint thanks to the improvement of shear strength. [ABSTRACT FROM AUTHOR]

This paper describes the effect of temperature (85 °C) and relative humidity (RH) (85%) on structure and material properties of an environmental-friendly Sn–3.0Ag–0.5Cu, in wt.% (SAC305) material. A detail microstructure characterization was performed by scanning electron microscope with EDS analysis, X-ray diffraction, electron backscattered diffraction and transmission electron microscope techniques. From this structural analysis, it is evident that in the as-cast alloy, submicron-sized acicular and spherical-shaped ε-Ag3Sn and very fine η-Cu6Sn5 intermetallic compound (IMC) particles are homogeneously distributed in fine β-Sn matrix grains. However, after exposing SAC305 alloy to 85 °C and 85% RH for 60 days, the coarsening of its microstructure was observed changing significantly the morphology (size and shape) of the IMCs as well as of the Sn matrix. The Sn matrix grains size (in diameter) in as-cast alloy ranges within 20–30 µm, while after heat treatment an increase in size of 35–45 µm was observed. Furthermore, the ε-Ag3Sn IMC particles appeared with coarse structure. Therefore, the mechanical properties of SAC305 material turned inferior that confirmed by electrical resistivity and mechanical properties measurements. The electrical resistivity and microhardness values were reduced by about 11.2% and 22%, respectively, with respect to the corresponding values of the reference alloy (as-cast alloy). However, the heat-treatment method enhanced the damping properties of SAC305 material. [ABSTRACT FROM AUTHOR]