Study on the Mechanism of CNTs Regulating the Microstructures and Properties of Al–Cu–Mg Alloy

The purpose of this study was to investigate the effect of carbon nanotube addition on the microstructure and mechanical properties of Al–Cu–Mg alloy composites. By analyzing the XRD results, it was deduced that the extruded and heat-treated composites, after the addition of CNTs, were preferentially grown on the (220) crystal plane. In addition, the distribution of carbon nanotubes at α-Al grain boundaries was observed by SEM and TEM. The incorporation of carbon nanotubes leads to an increase in the degree of recrystallization in the composite. It is worth noting that according to the study of the four strengthening mechanisms of dislocation strengthening, grain refinement strengthening, load transfer strengthening, and second stage strengthening, when the carbon nanotube content is 1.5 wt.%, the tensile strength (480.4 MPa) and yield strength (456.68 MPa) are significantly improved

The annealing microstructural evolution of Al-10Zn alloy prepared by continuous extrusion of mixed heterogeneous elemental powders

Al and Zn powders in the ratio of 9:1 (wt%) were alloyed into rods with a dense structure by using the continuous extrusion technique. To promote metallurgical bonding of heterogeneous elements, the microstructures of these rods with different holding times (1, 3, and 5 min) at the same annealing temperature were investigated. With the increase of annealing time, the microstructure consisted mainly of ( α -Al) and ( α  +  η ) phases and an ( α  + η )-rich phase. The solid solubility of Zn into Al also gradually increased. The calculated x-ray diffraction (XRD) data showed that the lattice parameter of Al decreased to 4.04793 Å after 5 min of annealing, which was decreased by 0.062% compared to the lattice parameter of Al in the powder state. The microscopic stress and dislocation density of Al were increased by 0.27% and 12.52 × 10 ^14 m ^−2 respectively after extrusion, and the microscopic deformation and dislocation density were decreased to 0.2% and 8.71 × 10 ^14 m ^−2 respectively after being annealed for 5 min. The dislocation density and lattice distortion after annealing gradually decreased with increasing annealing time, and the scanning electron microscopy (SEM) results indicated that the mass percentage of Zn increased with increasing annealing time

Effect of Polyvinylpyrrolidone Content on Pure Titanium Injection Molding

In water-soluble binder systems, polyethylene glycol (PEG) and polymethylmethacrylate (PMMA) are often used as primary and secondary components. The PEG/PMMA binder system is clean and environmentally friendly, but the discrepancy between the crystallization temperature of PEG and the glass transition temperature of PMMA leads to the generation of pores in the feedstock. The solidification pores have an adverse impact on the final mechanical properties of the samples. Polyvinylpyrrolidone (PVP), as a crystallization inhibitor, can inhibit the formation of porosity. In this study, spherical titanium powder with a diameter of less than 45 μm was used as metal powder; the binder system consisted of PEG, PMMA and SA. Different increments of PVP (0, 10%, 20%, 30 wt.%) were added to the PEG/PMMA binder system. The uniformity of the feedstock and the open channels generated after debinding were observed using SEM. The pores’ condition before and after debinding was studied using Micro CT, and the mechanical properties of the samples were also detected. By comparing the macroscopic and microscopic morphologies of the injected samples and mechanical properties of the sintered samples, it was found that a PVP content of 20 wt.% resulted in the best properties