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The remelting of aluminum scraps can result in the accumulation of impurities, with iron being the most prevalent among them. The presence of such impurities can cause downgrading and hindered utilization of the material. Despite this, the evolution mechanism of the Iron-containing Intermetallic Phase (IIP) in recycled high-Fe and low-Si aluminum melt has received limited attention and requires further investigation. This study investigates the evolution mechanism underlying the precipitation behavior and organization of the IIP during the solidification process of recycled high-Fe Al-Zn-Mg-Cu melts, utilizing a combination of simulation and experiment. Our findings indicate that the precipitation behavior of the high-temperature precipitation phase (HPP) in the melt is influenced by the Mn and Si, which subsequently determines the organization of the IIP. Specifically, the predominant forms of IIP in the recycled high-Fe Al-Zn-Mg-Cu alloys are lamellar and hollow rod-like phases with anisotropic, as well as skeletal phases with isotropic organization. Moreover, the synergistic addition of Mn and Si can increase the precipitation temperature (PT) and precipitation temperature interval (PTI) of the Al 15 (Fe,Mn) 4 Si 2 phase in the melt, leading to the transformation of the IIP into a skeletal organization that can be easily removed and has less impact on the material properties. These findings provide insights into alloy design strategies aimed at minimizing the impact of iron accumulation on the cycle life of aluminum scraps and the performance of recycled aluminum. [Display omitted] • Precipitation order of high-temperature precipitation phases determines the organization of iron-containing intermetallic. • Neither Mn nor Si addition can transform the iron-containing intermetallic from a lamellar to a skeletal organization. • Synergistic addition of Mn and Si leading to iron-containing intermetallic transformation into skeletal microstructure. • Designing the composition of recycled high-Fe melt is to enhance the precipitation order of the Al 15 (Fe,Mn) 4 Si 2. [ABSTRACT FROM AUTHOR]

Abstract: Fe3O4 nanoparticles were prepared by carbothermal reduction method using glucose as carbon source. Heating temperature and holding time effects on crystalline phase composition and magnetic properties of Fe3O4 nanoparticles were investigated by X-ray diffraction, field-emission scanning electron microscopy and vibrating sample magnetometer. Pure Fe3O4 nanoparticles with an average crystallite size of 48nm was obtained at higher heating temperature of 650°C and shorter holding time of 0.5h, or at lower heating temperature of 450°C and longer holding time of more than 6h. The crystallite size of Fe3O4 nanoparticles increases with heating temperature and holding time. Fe3O4 nanoparticles heated at 650°C for 2h have the highest saturation magnetization (M s =97.99emug−1), higher than Fe3O4 prepared by other techniques due to better microstructure, crystallinity and expanded crystalline cell. [ABSTRACT FROM AUTHOR]

Abstract: When sintered Sm(Co, Fe, Cu, Zr) z permanent magnets are prepared by metal injection molding, some organic binders are added in alloy powder, which leads to much residual carbon in the magnets. The residual carbon decreases magnetic properties and destroys the microstructure of the magnets. In this paper, the behavior of carbon in Sm(Co, Fe, Cu, Zr) z permanent magnets has been studied. The results indicate that Sm(Co, Fe, Cu, Zr) z magnets can keep excellent magnetic properties when the carbon content is below 0.1wt.%: Br≥10kGs, H cj ≥22kOe, BHmax ≥25MGOe. When the carbon content is above 0.1wt.%, Br, H cj and BHmax decrease with increasing carbon content evidently. Carbon consumes Zr content and forms ZrC, which reduces the volume fraction of the lamella and Sm(Co, Cu)5 phases. Thus, the cell size increases and the cellular microstructure deteriorates. When the carbon content reaches 0.43wt.%, there is not enough Sm(Co, Cu)5 phase to form a uniform cellular microstructure. Br, H cj and BHmax are approximate to zero. Since carbon has little influence on the content of Sm2(Co, Fe)17 phase, Ms can keep a high value (≥100emu/g). ZrC has high melting point (3420°C) and acts as dispersion particle in the magnets, which prevents the grains of SEM structure growing and reduces the liquid content of green compacts during sintering. Therefore, the density of the magnets decreases. [Copyright &y& Elsevier]

CaO MgO SiO 2 (CMS) glass-ceramics preparation normally needs two-step heat treatment (nucleation and crystal growth). In this work, CMS glass-ceramics are successfully produced by one-step heat treatment by building Ca 2+ and Mg 2+ fast diffusion layer between the residual glass and diopside crystal. High-temperature X-ray diffraction (HTXRD) shows that diopside crystals formed during the crystallization of CMS glass. At the glass layer between diopside crystal and residual glass, an enrichment of Na + is observed by energy dispersive spectroscopy line scanning (EDSLS), which increases the Si O Na bonds that promote Ca 2+ and Mg 2+ ions diffusion. This layer eventually promotes further growth or ripening of the diopside crystals. Thus, nucleation and crystal growth of the CMS glass proceed continuously at the crystallization peak temperature (T nc ), detected by differential scanning calorimetry. Thereby, one-step crystallization of the CMS glass-ceramics becomes possible and practical. [ABSTRACT FROM AUTHOR]

Recrystallization and austenization behavior of cold-rolled 0.22C-1.3Mn-1.4Si steel in continuous heating with 0.5 °C/s, 5 °C/s, 50 °C/s, 300 °C/s had been studied using dilatometry and metallographic analysis. It is found that heating rate strongly influences the overlap extent of ferrite recrystallization and austenite formation process which reflect on both of the dilatometric curves and the evolution of microstructures. At heating rate of 0.5 °C/s, thermal expansion coefficient declines and regresses before Ac1 which corresponding to the recrystallization begins and finishes. At higher heating rate, austenization begins partially with the deformed structures and recrystallization is still ongoing along with the austenite formation. The overlaps are proved to introduce the bias and errors in describing the kinetics of austenite formation measured from dilatometric curves by lever rule. Decoupled dilatometric curves which striped the deviation caused by recrystallization are established. The austenite fraction volumes measured by the new curve agree well with the results measured by quantitative metallography. [ABSTRACT FROM AUTHOR]

Secondary aluminum dross (SAD) and red mud (RM) are solid waste discharged from aluminum industry. SAD contains 10–25 wt% aluminum nitride (AlN) and RM contains 20–50 wt% iron oxide. In this work, porous metal-ceramic composite was in-situ made from SAD and RM. Iron oxide was reduced into Fe 2 Si by AlN, and the generated nitrogen created pores. It was studied that effect of raw material and thermal treatment on pore structure and properties of the composite. Porosity, bulk density and compressive strength of composite were 65.78%, 1.03 g/cm3 and 17.77 MPa, when SAD content was 40 wt% and sintering temperature was 1450 °C. About 95.9% of malachite green in waste water was adsorbed by composite after 24 h. The composite could be recycled by magnetic separation after adsorption, attributed to the magnetic Fe 2 Si. This work proposed a novel idea of making recyclable porous material for adsorption of organics in waste water. [Display omitted] • Porous metal-ceramic composite was in-situ made from SAD and RM. • Porosity and bulk density of composite were 65.78% and 1.03 g/cm3. • 95.9% of malachite green in waste water was adsorbed by composite after 24 h. • The composite could be recycled by magnetic separation after adsorption. [ABSTRACT FROM AUTHOR]

Abstract: Using spent alkaline Zn–Mn batteries as raw material, Mn–Zn soft magnetic ferrite nanoparticles are prepared by multi-step processes including acid leaching, chemical treatment of battery iron shells and citrate-nitrate precursor auto-combustion. Acid leaching and chemical treatment mechanisms are investigated. Dried gels thermal decomposition process, auto-combustion, phase composition, morphological and magnetic properties of as-prepared Mn–Zn ferrite nanoparticles are characterized by thermogravimetric and differential thermal analysis, X-ray powder diffraction, transmission electron microscopy and vibrating sample magnetometer. Synthesized Mn–Zn ferrite nanoparticles (Mn0.5Zn0.5Fe2O4) have pure ferrite phase, larger saturation magnetization (M s =60.62emug−1) and lower coercivity (H c =30Oe) compared with the same composition ferrites prepared by other techniques due to better crystallinity. Mn–Zn ferrite nanoparticles synthesis method presents a viable alternative for alkaline Zn–Mn batteries recycling. [Copyright &y& Elsevier]

This paper takes the recycled 7075 aluminum alloy as the object to study its smelting, extrusion and heat treatment processes. The composition, microstructure, mechanical properties and corrosion properties of recycled 7075 aluminum alloys were characterized by spectrometer, optical metallographic microscope, universal tensile testing machine, scanning electron microscope (SEM) and transmission electron microscopy (TEM). The results showed that the composition distribution of recycled 7075 aluminum alloy ingots was more uniform and the microstructure was more optimized. The tensile strength, yield strength and elongation of recycled 7075 aluminum alloy plates were higher than American Society of Testing Materials (ASTM) standard. The recycled 7075-T6 aluminum alloy plates had good corrosion resistance to salt spray. This paper aims to provide guidance for the smelting, extrusion and heat treatment processes of scrap aircraft aluminum alloy regeneration process, and to lay the foundation of the recovery and reutilization of scrap aircraft aluminum alloys. • We obtain the recycled 7075 aluminum alloy using scrap aircraft aluminum alloys. • A method is proposed to prepare the recycled 7075 aluminum alloy ingot. • The level-maintained reuse of scrap aircraft aluminum alloys is realized. • The extruded plates are obtained with one-step extrusion. • The mechanical properties of the extruded plates are better than ASTM standard. [ABSTRACT FROM AUTHOR]

Secondary aluminum dross is a solid waste discharged during aluminum processing and melting. Calcium aluminate glass-ceramics was manufactured from secondary aluminum dross without adding nucleating agent. Phase transition of glass-ceramics was studied. Nucleation temperature was set at 846 ℃ according to differential scanning calorimetry and X-ray diffraction results. Field-emission transmission electron microscopy was applied to observe microstructure of the thermally treated parent glass. During nucleation process, omphacite grew from glass network. Omphacite growth consisted of two steps: migration of silicon group and cation; growth of omphacite. After parent glass was thermally treated at 846 ℃ for 3 h, silicon group and cation migrated and formed silicon enrichment field. A little of omphacite crystal formed in silicon enrichment field. When thermal treatment time was increased to 12 h, more independent omphacite crystals grew in silicon enrichment field. The independent omphacite crystals grew larger and contacted with each other to form a large omphacite crystal. The large omphacite crystal became nucleus of glass-ceramics. Omphacite nucleation had two effects on crystallization of glass-ceramics. First, omphacite crystal became nucleus, which provided surface for growing crystals. Second, omphacite growth consumed silicon group in glass network, which decreased polymerization degree of glass network and promoted crystallization. In calcium aluminate glass-ceramics with silicon, omphacite crystal could act as the nucleus without additional nucleation agents. [Display omitted] • Calcium aluminate glass ceramics was made from the secondary aluminum dross. • Nucleation was attributed to omphacite growth. • Nucleation consisted of silicon groups migrating and omphacite growing. • Omphacite nucleation consumed silicon groups and promoted crystallization. • Omphacite acted as a novel nucleus in calcium aluminate glass ceramics with silicon. [ABSTRACT FROM AUTHOR]

Abstract: Radially oriented ring 2:17 type SmCo magnets have different microstructure in the radial direction (easy magnetization) and axial direction (hard magnetization). The structure of the cross-section in radial direction is close-packed atomic plane, which shows cellular microstructure. The microstructure of the cross-section in axial direction consists of a mixture of rhombic microstructure and parallel lamella phases. So the magnets have obvious anisotropy of thermal expansion in different directions. The difference of the thermal expansion coefficients reaches the maximum value at 830–860°C, which leads to radial cracks during quenching. The magnets have high brittlement because there are fewer slip systems in crystal structure. The fracture is brittle cleavage fracture. [Copyright &y& Elsevier]

Highlights: [•] Magnetic warm compaction technology was utilized to prepare bi-layered ME composite. [•] The ME coefficient of newly prepared composite was enhanced. [•] Magnetic warm compaction technology is suitable for preparing Terfenol-D composite. [•] The magnetic field is key factor in the magnetic warm compaction technology. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes controlled synthesis of Fe3O4 powder via carbothermal reduction method using pure Fe2O3 powder and glucose mixture as starting materials. Pure Fe3O4 powders were produced when glucose mole fraction was greater than 1/24. However, below 1/24 glucose mole fraction, only mixed Fe3O4 and Fe2O3 powders were obtained. Glucose is the source of carbon and CO gas, both of react with Fe2O3 to form Fe3O4. At 1/24 glucose mole fraction the lowest carbon content in reaction products was 0.018%, which increased with the glucose mole fraction. Possible carbothermal reduction mechanisms and Fe3O4 powder magnetic properties were investigated. The carbothermal reduction method for Fe3O4 synthesis has merits; it is not dangerous, controllable, and is suitable for large batch production, leading to novel applications of Fe3O4 powders. [Copyright &y& Elsevier]