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Abstract Al-6Cu-6Mg-5Sn-3Ga- x In (x = 0, 0.5, 1, 3, 5. mass. fraction) alloys were prepared using melting and casting technique. The microstructures and properties of the alloys were investigated by X-ray diffraction, scanning electronic microscope/EDX, electron microprobe analysis, Vickers hardness, compression properties, immersion tests and electrochemical measurements. The results show that the main phases of the alloys with the indium element consist of α -Al, Al 2 MgCu, Mg 2 Sn and Al-In eutectic phases. The Al-In phases segregates in α -Al grain boundaries. The gallium elements solid solution in the matrix alloys. When the addition of In contents is 1 mass.%, the hardness of the Al-6Cu-6Mg-5Sn-3Ga-1In alloy reaches to 142HV, and the compressive strength up to 582 MPa. The Mg 2 Sn and the Al-In eutectic phases are the source of the degradation reaction, and the driving force to continue is the concentration of Al in the eutectic phase. The relationship between the degradation corrosion rate and temperature, indium element content and other factors were also discussed in this paper. Graphical abstract Image 1 Highlights • Microstructure, mechanical properties and corrosion behavior of Al-6Mg-6Cu-5Sn-3Ga- x In alloys were firstly investigated. • The investigated alloys mainly consist of α -Al matrix, Al 2 MgCu, Mg 2 Sn and Al-In eutectic phase. • The investigated alloy has a maximum degradation rate reaches 98.51 mg/(cm2 h) at 93 °C. [ABSTRACT FROM AUTHOR]

The microstructures and mechanical properties of as-cast Mg-5Nd- x Al ( x = 0, 0.8, 1.6, 2.4 and 3.0 wt%) were investigated by the optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) and uniaxial tension test. The addition of 3.0 wt% Al led to the most significant grain refinement of Mg-5Nd alloy with the reduction of average grain size from 448 μm to 68 μm. The grain refinement was attributed to the formation of Al 2 Nd particles as the Al 2 Nd particles acted as effective grain refiners for the Mg matrix confirmed by XRD analysis, SEM observation, and crystallography calculation. The mechanical properties of as-cast Mg-5Nd alloy increased obviously after the addition of Al. The yield strength, ultimate tensile strength and elongation of the as-cast Mg-5Nd-3.0Al alloy were enhanced by about 45.3%, 72.4% and 264.0%, respectively, compared to as-cast Mg-5Nd alloy. The improvement of mechanical properties was mainly ascribed to the refined grains and secondary phase strengthening. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HA) has been broadly employed for bone treatment applications. In the present research, HA was extracted from hen, goat and cattle bone. Samples were prepared by cold isostatic pressing method (CIP) and sintered at 1100, 1200 and 1300 °C. In order to evaluate the characteristics of the produced HA, X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier Transform spectroscopy (FTIR), scanning electron microcopy (SEM) and energy dispersive spectroscopy (EDS) analyses were carried out on it. Hardness and compression tests were examined before and after sintering. Also, the morphology of the samples at different sintering temperatures was studied by SEM imaging. The obtained experimental results ascertained that with increasing the sintering temperature up to 1300 °C, relative density and hardness of the samples increased. Finally, compressive strength of the sintered sample at 1200 °C was determined as maximum value. [ABSTRACT FROM AUTHOR]

This work aimed at investigating the superiorities of multilayer graphene (MLG) and β-Si 3 N 4 whisker (β-Si 3 N 4w) in synergistically enhancing the toughness of Si 3 N 4 ceramic composites. First, Si 3 N 4 ceramic composites with hybrid 1 wt% MLG and 0 – 5 wt% β-Si 3 N 4w were sintered by spark plasma sintering. Phase constitutions and microstructures of Si 3 N 4 -based ceramic composites were characterized by X-rays diffraction, Raman spectra, and scanning electron microscope. Then, the optimal β-Si 3 N 4w content and sintering process of MLG/β-Si 3 N 4w -toughened Si 3 N 4 ceramic composites were comprehensively optimized by orthogonal experiments. Results indicated that in the case of maintaining the hardness of 15.87 – 18.84 GPa, the fracture toughness of Si 3 N 4 ceramic composites incorporated with 1 wt% MLG and 3 wt% β-Si 3 N 4w was advanced to 11.04 MPa·m1/2, which was 11.29% and 87.12% higher than that of 1 wt% MLG- and 3 wt% β-Si 3 N 4w -reinforced Si 3 N 4 ceramic composites, respectively. Orthogonal experiments demonstrated that 1 wt% MLG/3 wt% β-Si 3 N 4w -toughened Si 3 N 4 ceramic composites sintered at 1600 ℃, 40 MPa, and holding time for 6 min had optimum comprehensive mechanical properties. MLG wrapping and the synergistic effects of pull out, crack deflection, crack branching, and bridging resulted by MLG and β-Si 3 N 4w were the main responsible for the enhancement of toughness. [Display omitted] • MLG/β-Si 3 N 4w synergistic toughened Si 3 N 4 ceramics were sintered by SPS. • Fracture toughness of Si 3 N 4 -based ceramics was enhanced to 11.04 MPa·m1/2. • Optimal contents of MLG and β-Si 3 N 4w were 1 wt% and 3 wt%. • Optimum sintering process were 1600 ℃, 40 MPa, and holding time for 6 min. [ABSTRACT FROM AUTHOR]

Cu-1 wt%Al 2 O 3 composite powder, prepared by mechanical milling and consolidated by spark plasma sintering to have about 98–99% of theoretical density, were characterized by scanning electron microscope, focused ion beam microscope, X-ray diffraction, nanoindentation and transmission electron microscope. The mechanically milled powders, upon consolidation, exhibited a finer grain size of 2 μm. Tensile deformation behavior of this composite, at ambient temperature but over the strain rates of 10 −4 s −1 to 5 × 10 −2 s −1 , exhibited typical manifestations of dynamic strain ageing in the form of serrations and negative strain rate dependence of flow stress. The yield and ultimate tensile strengths, and so also the elongation decrease gradually with increase in strain rate. Such variation was also shown by nanoindentation hardness as a function of loading rate over 1–100 mN/s. The observed results are explained by the dislocation structure evolved from its interaction with Al 2 O 3 dispersoids and impurity atoms like Fe, C and O coming from the powder processing. [ABSTRACT FROM AUTHOR]

To optimize the mechanical properties of Ti(C,N)-based cermets used as tool materials, the cermets with different Ni–Co binder contents and Co/(Ni + Co) weight ratios were prepared. The effects of metal binder content and Co/(Ni + Co) ratio on the microstructure and mechanical properties of Ti(C,N)-based cermets were investigated by scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and measuring the transverse rupture strength (TRS), Vickers hardness ( HV ) and fracture toughness ( K IC ). The experimental results reveal that increasing Ni–Co binder content can increase the thickness of rim phases by improving the solid solution reaction and the wetting of hard phases. The cermets with 25 wt.% binder addition present good comprehensive mechanical properties, which is attributed to the moderate rim phases and uniformly distributed Ti(C,N) grains. The Co/(Ni + Co) weight ratios in binder have a great influence on the grain sizes and microstructure features of Ti(C,N)-based cermets, in virtue of the synergic effects between the wettability of Co and the solubilizing capacity of Ni on hard phases. The cermets with pure Co as binder exhibit optimal mechanical properties with a TRS of 1767 ± 81 MPa, a hardness of 12.26 ± 0.10 GPa and a K IC of 8.40 ± 0.47 MPa m 1/2 , which meet the requirements for tool materials. And the cermets with a Co/(Ni + Co) ratio of 0.2 have the second best mechanical properties with a TRS of 1848 ± 201 MPa, a hardness of 11.12 ± 0.40 GPa and a K IC of 9.43 ± 0.54 MPa m 1/2 , in which the lower hardness can be further improved by optimizing the compositions and sintering process. [ABSTRACT FROM AUTHOR]

Abstract: Single-wall carbon nanotubes (SWCNTs) functionalized 63Sn–37Pb solders was synthesized. Composite solders up to 1wt.% reinforcement of SWCNTs were prepared. The composite specimens were characterized by X-ray diffraction (XRD), Field-emission scanning electron microscope (FE-SEM). Melting characteristics of the SWCNT based solders were determined by differential scanning calorimetry. Microstructures of the composite solders were examined by FE-SEM at higher magnification for the observation of the CNT distribution. Mechanical properties of the composite specimens were compared with those of the pure 63Sn–37Pb solder specimens and found that the ultimate tensile strength increased by 30% with the 0.3wt.% addition of CNTs. Hardness values of the CNT based composites have shown higher Vickers hardness compared to un-reinforced counterparts. The enhanced mechanical properties are resulting from the possible load-transfer mechanisms of the CNTs, which is discussed in detail. The fractrographic examination conducted by FE-SEM indicated the existence of ductile features in the form of dimples in all the composite solders with different weight proportions; it is evident from the micrographs that much reduced ductility is observed in the specimens reinforced with the higher wt.% of CNTs. [Copyright &y& Elsevier]

The chemically architectured alloys were proposed as a new concept of microstructure, with a multi-scale architecturation. They are composed of a solid-solution at the atomic scale, grain boundaries and composition gradients at the micronic scale and finally a 3D network of gradients at the mesoscale. Composition gradients are between two phases with the same crystalline structure but different compositions. As a first application of this concept, powders of pure Ni and CoCrFeMnNi high entropy alloy were successfully densified by Spark Plasma Sintering. Then the microstructure and mechanical properties were characterized by scanning electron microscope coupled with energy dispersive spectroscopy and electron backscattered diffraction, X-ray diffraction, nanoindentation and compression tests. The obtained chemically architectured alloys present a homogeneous distribution of the two phases with a 10 μm wide chemical gradient in between. By comparison with reference non architectured materials, the chemical architecturation induces a 35% increase of the yield strength. Thus the concept of chemically architectured metallic alloys and composition gradients was proven as very promising: processing of this complex microstructure is possible and it induces a significant mechanical strengthening. Image 1 • A mixture of CoCrFeMnNi and Ni powders was fully densified by spark plasma sintering. • A chemical gradient of around 10 μm was formed between HEA and Ni phases. • This material is called a chemically architectured alloy. • Mechanical strength is improved compared to an ideal mixture of Ni and CoCrFeMnNi. [ABSTRACT FROM AUTHOR]