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In the present work, advanced aluminium metal matrix composite reinforced by nanomaterials is reported. The materials used for the experiments are AA6061 aluminium alloy, compounded with inorganic nanotubes (INT) and fullerene-like (IF) nanoparticles of WS 2 . Aluminium metal matrix composite with different weight percentage (0.1–0.5 wt%) of the INT and IF were prepared. Both the AA6061 aluminium and the aluminium metal matrix nanocomposites (MMCs) were re-melted by the stirring-casting method. Mechanical properties and microstructure analysis of the nano-MMCs were conducted. The measurements have shown that the hardness, yielding strength, ultimate tensile strength, and ductility were improved by up to 68% compared to the neat alloy for nanoparticles concentrations the range of 0.2 wt%. Metallography microstructure analysis showed that increasing the WS 2 INT or IF nanoparticles weight percentage in aluminium metal matrix composite, resulted in a more refined grains. The grain size of the composite matrix was reduced by up to 48.4% compared with that of neat AA6061 alloy ingot. Scanning electron microscope (SEM) analysis showed that addition of 0.5 wt% of WS 2 nanotubes into the Al matrix resulted in INT agglomeration which had deleterious effect on the tensile strength. The composite materials reinforcement mechanism was studied. This analysis showed that the improved mechanical properties of the metal nanocomposites can be predominantly attributed to the differences in thermal expansion coefficients of the WS 2 INT (or WS 2 IF nanoparticle) and the AA6061 alloy. [ABSTRACT FROM AUTHOR]

This study analyzes the effect of substitution of Ni for Zn on microstructure and mechanical properties of Mg–Gd–Y–Zn–Mn alloy. Our results show that the volume fraction of Mg5(Gd, Y) and (Mg, Zn)3RE phase decreased and LPSO phase increased with more substitution of Ni. After homogenization, only α-Mg and LPSO phase existed. In Mg–Gd–Y–Zn–Mn alloys, the LPSO phases mainly consisted of the 14H type. While in Mg–Gd–Y–Ni–Mn alloy, the LPSO phases consisted of the 18R type. In addition, compared with Mg–Gd–Y–Zn–Mn alloy, the mechanical properties of as-extruded Ni-substitution alloys were improved due to the better refinement of the size of grains and LPSO phases. The tensile strength in as-extruded Mg–Gd–Y–Ni–Mn alloy could reach up to 400 MPa with 18% of the elongation to failure. [ABSTRACT FROM AUTHOR]

AZ91 reinforced with four different concentrations (0,0.3,0.6,1)wt% of WS 2 micro particles were fabricated using stir casting method. The samples were deformed by equal channel angular pressing (ECAP) after homogenization. The scanning electron microscopy and X-ray diffraction were used to investigate the microstructure and phase composition respectively. The results reveal that rod-like precipitates produced during the homogenization process are refined and bounded in the grain boundaries by the combined effect of WS 2 enrichment and increasing number of passes of ECAP. The needle precipitates are eminent in 1pass 0.3 wt%WS 2 /AZ91. The β-Mg 17 Al 12 and extracted Al particles are dissolved and secondary phases are produced by dynamic recrystallization after 2pass 1 wt%WS 2 /AZ91. The maximum crystallite size and microstrain distribution have been observed for 1pass 0.6 wt%WS 2 /AZ91. The mechanical properties investigation represents that 2pass 0.6 wt%WS 2 /AZ91 has optimal yield strength and ultimate tensile strength. The (22.143)%, (44.735)% and (92) % increment in yield strength, ultimate tensile strength and elongation have been observed in 2pass 1 wt%WS 2 /AZ91 compared with homogenized monolithic AZ91 alloy respectively. The maximum young's modulus (6696.218MPa) has been found for 1pass homogenized WS2/AZ91 and minimum (4108.165MPa) for homogenized 0.6 wt%WS 2 /AZ91. The ECAP deformed 1pass 0.3 wt%WS 2 /AZ91 exhibits the maximum strain hardening rate. The YTS, UTS, and elongation are (30.41) %, (47.6) % and (51.9)% increased after 2pass-0.6 wt%WS 2 /AZ91. [ABSTRACT FROM AUTHOR]

In this work, AZ91 magnesium alloy reinforced with a low fraction (0–1) wt.% tungsten disulfide(WS 2) microparticles have been fabricated using stir casting method. Effects of WS 2 microparticles on mechanical properties, microstructure, and their correlation have been analyzed. The microstructure of composites has been investigated by scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS) and X-ray diffractometer. Results indicate that density, hardness, ultimate tensile strength (UTS), and tensile ductility have a direct relation with reinforcement (WS 2) contents and has optimal value for 0.6 wt% WS 2 /AZ91 composites then slightly decrease afterward. The UTS and hardness of 0.6 wt%WS 2 /AZ91 were increased by 23.23% and 10.65% respectively with respect to monolithic AZ91. The ultimate compressive strength(UCS) is directly related with WS 2 concentration and 10.07% enhancement in UCS for 1 wt%WS 2 /AZ91 composites have been noted. The trend is interlinked with density and hardness of composites. SEM images depict, WS 2 micro-particles suppress β-Mg 17 Al 12 precipitates, refine the microstructure and enhance the grain size resulting in an increase in mechanical properties. The improvement in microstructure and mechanical properties is attributed to the dispersion of WS 2 particles which hinder the grain growth. The increase in porosity has causes the decrease in mechanical behavior of 1 wt%WS 2 /AZ91. Twin boundary fracture has been found major fracture phenomenon in fractured WS 2 /AZ91 surfaces. • WS 2 /AZ91 metal matrix composites have been manufacture by stir casting method. • Density and porosity of WS 2 /AZ91 composites has been assessed. • Mechanical behavior under compression and tension has been analyzed. • Effect of WS 2 on microstructure has been investigated. • Fracture behavior of composites has been studied. [ABSTRACT FROM AUTHOR]

A high-strength Mg-8.8Gd-3.8Y-1.0Zn-0.7Mn (wt%) alloy hollow profile with complex cross-section was successfully fabricated through porthole die extrusion, and its weld seam was analyzed for microstructure and element distribution to investigate the impact of solid-state bonding. The weld seam displayed a homogeneous magnesium grain structure and a precipitation-free zone. The diffusion behavior of alloying elements during solid-state bonding significantly affected the microstructure of the weld seam, with Gd and Y atoms diffusing towards the outside of the weld region. The hollow profile exhibited favorable mechanical properties, with an ultimate tensile strength (UTS) of 470 MPa, a tensile yield strength (TYS) of 309 MPa, and an elongation (EL) of 7.4%, and showed a minor negative effect from the weld seam. • High-strength Mg-Gd-Y-Zn-Mn alloy hollow profiles showed a favorable metallurgical bond in the weld seam with a homogeneous magnesium grain structure and no microvoids. • Alloying element diffusion influenced the weld seam microstructure, resulting in lower concentrations of Gd and Y in the weld region, while Zn and Mn showed a more uniform distribution. • The presence of the weld seam had minimal impact on the overall mechanical properties of the hollow profiles, which retained superior mechanical performance. [ABSTRACT FROM AUTHOR]

Abstract: This study investigates the effects of heat treatment on the morphology of long-period stacking ordered phase (LPSO) and the corresponding mechanical properties of Mg–9Gd–xEr–1.6Zn–0.6Zr (1–4wt%) using optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectrometry, X-ray diffraction, transmission electron microscopy, and tensile tests. The microstructure analysis of the as cast alloys showed that the volume fraction of the (Mg, Zn)3(Gd, Er) phase increased with increasing Er content. The (Mg, Zn)3(Gd, Er) phase in grain boundaries transformed into the 14H-LPSO phase Mg12Zn(Gd, Er) after heat treatment between 400°C and 515°C. The bulk shaped LPSO phases distributed along the grain boundaries produced isometric crystal grains in and enhanced the ductility of the as-extruded alloys. However, the lamellar LPSO phases precipitating in the grain interior induced strip-shaped grains in and improved the strength of the as-extruded alloys. [Copyright &y& Elsevier]

The ageing behavior of as-extruded Mg-1.5Gd-1.3Y-0.6Zn-0.6Mn (at%) alloy was investigated. The strength and ductility are simultaneously improved during ageing at the peak hardness platform. The alloy aged for 100 h exhibits ultrahigh ultimate tensile strength (UTS) of 538 MPa and good elongation to failure (EL) of 13.1%. [ABSTRACT FROM AUTHOR]

Bending forming causes significant inhomogeneous material strength distribution (MSD) in hydrogenation reactor shells. Tempering can improve this problem before the long-term service of hydrogenation reactors, but its effect is still unclear. In this work, we investigated the impact of tempering on the material strength inhomogeneity in hydrogenation reactor shells. First, 650 °C plastic deformation as well as 705 °C × 8 h tempering was performed on 2.25Cr–1Mo-0.25V tensile specimens. Yield strength (YS) and ultimate tensile strength (UTS) of these specimens were measured. Then, an artificial neural network (ANN) was constructed based on the experimental results, and it was further utilized to establish MSD prediction model that can predict actual MSDs in ring shells before and after tempering. Thereafter, the tempering effect was discussed in details via comparing predicted MSDs in un-tempered and final reactor shells. At last, the tensile specimens were also observed by scanning electron microscope (SEM). Image identification technology was applied in obtained SEM profiles to quantitatively analyze size and number of carbides. Results showed that the maximal absolute relative errors were 4.97% and 7.89% for ANN and MSD predictor, respectively. The coarsening behavior of carbides could explain the discrepancy in strength after tempering between 2.25Cr–1Mo-0.25V steels with different warm deformation extents. This work will contribute to the lightweight design of hydrogenation reactors. • ANN can well predict synergistic impact of warm forming and tempering on high temperature strength of 2.25Cr-1Mo-0.25V. • The constructed MSD predictor is a reliable model for lightweight design, and its absolute relative error is below 7.89%. • Tempering can reduce the material strength inhomogeneity caused by warm bending, but leads to a great material strength loss. • Carbide coarsening can explain strength discrepancy in 2.25Cr-1Mo-0.25V steels with different warm deformation extents. [ABSTRACT FROM AUTHOR]