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One of the major obstacles restricting the wide applications of Mg alloys is their low Young's modulus at ∼45 GPa, which is uncompetitive to Al alloy over 60 GPa. To resolve this issue, we proposed a new strategy of designing ultra-light Mg-Li alloys by employing the microscale compounds in both HCP and BCC grains to achieve high Young's modulus. HCP or BCC alone cannot achieve a high modulus due to the segregation of solutes at the grain boundaries and the formation of brittle intermetallics in the interdendritic region. We designed chemistry that is so perfect to arrest the excess solutes inside the BCC matrix during solidification and engulf pre-solidified rare earth particles by HCP primary grains which have such a lean chemical composition that has almost no segregation. During solution heat treatment, the dissolution of solutes pushes the BCC boundary towards HCP grains by Ostwald ripening (BCC structures are interconnected but the HCP structures are isolated). During low-temperature aging heat treatment, nucleation of HCP structure on the rare earth particles inside the BCC grain is found, degrading the strength. Therefore, a novel Mg-Li-Al-Zn-Y-Mn-Gd (LAZWMV) alloy with a very high modulus was designed which reaches Young's modulus as high as 61.4 GPa. Micro-compounds (AlLi and Al-X) with average equivalent diameters of 3.76 µm and 6.55 µm were quantified in 3D using X-ray computed tomography and nanoindentation tests for establishing the microstructure-modulus correlation. The influence of Li addition on Mg-Mg was calculated by DFT calculations and the mechanism of modulus improvements has been proposed. [Display omitted] • Ultra-light Mg-Li alloy was designed with high strength and high modulus. • Super-high Young's Modulus of 61.4 GPa was first reported for a novel Mg alloy. • Nanoindentation uncovers the principles of modulus increase in Mg-Li alloys. • Quantitative 3D characterization of high modulus phase using XCT prectict alloy properties. • DFT calculation of Mg-Mg bonds explores the effects of heat treatments. [ABSTRACT FROM AUTHOR]

LiCoPO4 is a promising cathode material for use in high voltage Li-ion batteries. One of the problems with LiCoPO4 is limited cycle life. One possible cause for the limited cycle life of LiCoPO4 is mechanical degradation. As a consequence, the mechanical properties, elastic modulus, E, and fracture toughness, KIC, of hot-pressed dense (~98%) polycrystalline (15-20 µm) single phase LiCoPO4 were investigated. E for the hot-pressed LiCoPO4 specimen is ~137 GPa while the E value for the LiCoPO4 specimen after annealing at 600 °C is ~106 GPa. The fracture toughness of the hot-pressed LiCoPO4 sample is ~0.41 MPa m1/2, which increased to ~0.53 MPa m1/2 after annealing. These low KIC values reveal that LiCoPO4 is a brittle material. It is believed that the decrease in E and increase in KIC with annealing is associated with a reduction in residual stress. [ABSTRACT FROM AUTHOR]

Highlights: [•] Hardness of cured UF resins was evaluated by nanoindentation technique. [•] Both HB and HM value was consistently changed as a function of F/U mole ratio. [•] However, both Er and Es of cured UF resins displayed inconsistent trend. [•] Both HM and Er showed much greater in the COV at lower F/U mole ratios 1.0 and 1.2. [•] Crystalline structures in the low F/U mole UF resins contributed to this variability. [ABSTRACT FROM AUTHOR]

Abstract: Nanoindentation was applied to determine the elastic moduli in the compression mode of films of fluorinated ethylene propylene copolymers (FEP) foamed by means of supercritical carbon dioxide. For this purpose, a flat punch indenter with a diameter larger than the average cell size of the foams was found to be appropriate. The dependence of the mechanical properties of the films on their cellular structure was investigated by varying material and process parameters: molar mass of the FEP, the magnitude of the pressure drop and the temperature during the foaming process. The elastic modulus showed a strong influence of the cellular structure of the films. A decrease of the molar mass of FEP as well as an increase of pressure drop and foaming temperature considerably reduced the elastic modulus of the foams generated. This lowering of the stiffness correlated with the decrease of foam density. In addition, a significant contribution of the cellular morphology and the thickness of the compact skin layers of the foams could be noted. A further reduction of the foam stiffness was achieved by a biaxial stretching of the foams, which deformed the cells into a lens shape. [Copyright &y& Elsevier]

Abstract: Thin organic films of octadecyltrichlorosilane (OTS) and aminopropyltriethoxysilane (APTES) were deposited on oxidized Si(111) substrates and characterised using atomic force microscopy (AFM) and nanoindentation methods. Films derived from a novel alkylsilane, 4-[N,N-(2-pyridyl)aniline]triethoxysilane (NDTS), which has properties similar to related electroluminescent and fluorescent compounds, were also examined. This latter compound could be used to directly couple a fluorescent or electroluminescent centre to a semiconductor surface, with applications in microfluidics or other microelectronic-based sensors. AFM images showed that when OTS or APTES was deposited from ethanol solution onto the oxidized Si surface, an inhomogeneous film was formed, containing both smooth regions and polymerised particles of the alkylsilanes up to 200nm in diameter. Nanoindentation force/displacement curves could clearly distinguish these two regions of the film, and they showed quite different mechanical properties. When deposited from a solution of ethanol and CH2Cl2, OTS films were smooth and completely covered the surface. Discontinuities in the force/displacement curves, corresponding to a breakthrough by the indentor through the film into the substrate showed that these films were some 2nm in thickness. When OTS, APTES or NDTS were deposited from CH2Cl2 solution, similar discontinuities could be observed, and showed that the film thickness increased, and roughness decreased, as the concentration of alkylsilane in solution was decreased. The results are discussed in the context of using nanoindentation methods as a means of characterising organic thin films. [Copyright &y& Elsevier]