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Heterostructured Al/10 vol% (TiC-GNPs) composites were produced by powder metallurgy (PM) with different TiC-to-GNPs volume ratios. As the TiC-to-GNPs ratio decreases, the improved dispersion of TiC in the matrix is achieved and the heterostructure of the composite is optimised due to the decreased TiC fraction and increased interaction between TiC and GNPs. Besides, compressive properties of the composite are improved significantly, and a balance of the significantly increased strength (σYS of 481.0 MPa and σUCS of 651.4 MPa) and reasonably remained ductility (εf of 10.9%) is achieved in the Al matrix composite reinforced with 8.5 vol% TiC and 1.5 vol% GNPs (A4) based on the optimised TiC-to-GNPs ratio and optimised heterostructure. However, the compressive properties decrease dramatically when the GNPs content reaches 2 vol% because of the presence of GNPs agglomerates. ....
The microstructures, mechanical properties and corrosion behaviors of the ultra-high strength Al–Zn–Mg–Cu-Sc aluminum alloy fabricated by wire-arc additive manufacturing process using a self-prepared 7B55-Sc filler wire were systematically investigated under different heat treatments. The results showed that the microstructures of the as-deposited, T6, T73, and retrogression and re-aging (RRA) heat treatments were all composed of fine equiaxed grains with a size of about 6.0 μm. The grain boundary precipitates (GBPs) of the as-deposited sample were very coarse and continuously distributed along the grain boundaries, and the intragranular precipitates (IGPs) mainly consisted of a small amount of ηMg(Zn,Cu,Al)2 and η′ phases. After T6 heat treatment, the GBPs became much finer, but still continuously distributed along the grain boundaries. The IGPs mainly consisted of fine GP zones and η′ phases. After RRA heat treatment, the GBPs became coarser and discontinuously distribu ....
Core densification in superconducting wire is highly desirable for obtaining high performance superconducting wires. Since voids hinder current flow in the superconducting core and they directly affect electrical property. In this study, we proposed a magnesium powder blending to regulate the porous properties. Our study delved deeper into the relationship between various particle parameters (such as particle size and distribution), impurities (MgO and Mg(OH)2), superconducting transition temperature, and current carrying capacity for MgB2 superconducting wires. We found a significant correlation between these factors and the porous properties. In particular, the blending of raw powders having spherical shape enables tuning of morphological structures and crystallinities inside cores of the power-in-tube processed MgB2 wires, resulting in superior superconducting properties. Our finding provides in-depth insights of methodological approaches towards more widespread use of superconducti ....
The spring fastener is one of the key parts of the rail track, which provides buckle pressure to keep track gauges. A high-performance spring fastener can greatly improve railway-running safety. In this investigation, on the premise of fully studying the processing process of spring fasteners, the static CCT curve of spring fasteners is determined using the thermal expansion method combined with metallographic microstructure observation and hardness test, and the post-heat-treatment process is comprehensively studied. When the tempering temperature is 460 °C, the metallographic microstructure and tests of mechanical properties well meet the technical requirements of the high-speed railway spring fastener. The studies conducted in this investigation has a valuable guiding effect on the thermal processing technology of high-speed railway spring fasteners. ....
Basalt rock waste is a major industrial waste generated as a result of quarrying rocks and artificial sand manufacture for construction projects, and its disposal can lead to several landfill hazards. However, it shows potential to be used as a source material for the manufacture of geopolymers. This paper presents the triaxial stress-strain characteristics of a novel geopolymer developed from basalt rock waste considering partial replacement with ground granulated blast furnace slag (GGBFS) up to 30%. A detailed mix design investigation revealed the optimum molarity (M) of the sodium hydroxide solution to be 8M and the optimum ratio (R) of sodium silicate to sodium hydroxide solution to be 0.75. The axial stress-strain relationships were developed after a series of triaxial laboratory tests for low confining pressures (0 to 800 kPa) and Hoek cell tests for high confining pressures (1 to 5 MPa). A constitutive model predicting the complete stress-strain behavior is proposed. The geopol ....