[en] The red-emitting phosphor In₂(MoO₄)₃:Eu³⁺ with cubic crystal structure was synthesized by a conventional solid-state reaction technique and its photoluminescence properties were investigated. The prepared phosphor can be efficiently excited by ultraviolet (395 nm) and blue (466 nm) light. The emission spectra of the phosphor manifest intensive red-emitting lines at 612 nm due to the electric dipole ⁵D₀→⁷F₂ transitions of Eu³⁺. The chromaticity coordinates of x=0.63, y=0.35 (λ_ex=395 nm) and x=0.60, y=0.38 (λ_ex=466 nm) are close to the standard of National Television Standard Committee values (NTSC) values. The concentration quenching of In₂(MoO₄)₃:Eu³⁺ is 40 mol% and the concentration self-quenching mechanism under 466 nm excitation was the d---d intereaction. As a result of the strong emission intensity and good excitation, the phosphor In₂(MoO₄)₃:Eu³⁺ is regarded as a promising red-emitting conversion material for white LEDs. - Highlights: ► A novel red-emitting phosphor In₂(MoO₄)₃:Eu³⁺ for LEDs was synthesized. ► The phosphor can emit red light under the excitation by UV or blue LEDs. ► The PL intensity achieves the maximum when the concentration of Eu³⁺ is 40 mol%. ► Concentration self-quenching of Eu³⁺ excited at 466 nm is due to d---d interaction.

[en] Copper diffusivities were measured in both α single phase and α plus silicon phase Al-Cu-Si alloys by diffusion couple experiments. The results exhibits that copper atoms has much faster diffusion rate in the α plus silicon phase Al-Cu-Si alloy than in the α single phase Al-Cu-Si alloy, which means silicon phase plays an important role in copper diffusion in the alloy. Copper has very high diffusivity in the silicon phase, silicon particles become shortcuts for copper diffusion in the alloy. How much the silicon phase can increase copper diffusivity depends on silicon's volume percentage and morphology

[en] This paper deals with diffusivity measurements for Cu and Si atoms in Al-Cu-Si alloys by diffusion couples. With Cu and Si concentration profiles in the diffusion couples treated by different heating temperatures and times, their diffusivities including D _CuCu, D _SiSi, D _CuSi and D _SiCu in Al-Cu-Si ternary alloys could be calculated and their D ₀ and Q also could be obtained by their diffusivities under different temperatures

[en] Phytic acid (PA) conversion coating on AZ61 magnesium alloy was prepared by the method of deposition. The influences of pH, time and PA concentration on the formation process, microstructure and properties of the conversion coating were investigated. Scanning electron microscopy (SEM) was used to observe the microstructure. The chemical nature of conversion coating was investigated by energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) techniques. The corrosion resistance was examined by means of potentiodynamic polarization method. The adhesive ability was tested by score experiments. The results showed that the growth and microstructure of the conversion coatings were all obviously affected by pH, time and PA concentration. In 0.5 mg/ml PA solution with a pH of 5, an optimization conversion coating formed after 20 min immersion time by deposition of PA on AZ61 magnesium alloy surface through chelating with Al³⁺. It made the corrosion potential E_corr of sample shifted positively about 171 mV than that of the untreated sample, and the adhesive ability reached to Grade 1 (in accordance with GB/T 9286).

[en] The microstructures and tensile properties of extruded Mg-1Gd-0.5Zn-xCe sheets with various Ce contents (0, 0.3, 0.7 and 1.2 wt%) were investigated at room temperature. Ce addition refined the grain size and resulted in the formation of new Mg₁₂Ce phases. The volume fraction of Mg₁₂Ce phases increased with the increase of Ce additions, which impeded the growth of dynamic recrystallized grains during extrusion and consequently led to the texture weakening of Mg-1Gd-0.5Zn based sheets. Grain refinement and massive Mg₁₂Ce phases provided the highest strength in the Mg-1Gd-0.5Zn sheet with 1.2 wt% Ce addition. Moreover, due to more basal slip, pyramidal slip activity and uniform strain distribution, the ductility of extruded Mg-1Gd-0.5Zn sheet with 0.3 wt% Ce addition along the extrusion direction exhibited the maximum value of 33.6%, which was approximately 17.9% higher than that of the Mg-1Gd-0.5Zn sheet. However, with the further increase of Ce additions (0.7 and 1.2 wt%), the ductility of the sheets deteriorated gradually, which was associated with the increase of coarse Mg₁₂Ce particles.

[en] Highlights: • Sn addition can improve the mechanical properties of the extruded Mg–Zn–Mn alloy. • T6 treatments can markedly improve the strengths of the extruded Mg–Zn–Mn–Sn alloys. • Mg–6Zn–1Mn–4Sn alloy with double aging treatment exhibits the highest strengths. • High strength is attributed to combined precipitation strengthening of β₁^′ and Mg₂Sn. -- Abstract: The microstructure and mechanical properties of Mg–6Zn–1Mn alloys with varying Sn contents (0, 1, 2, 4, 6, 8 and 10 wt.%) have been examined using optical microscopy (OM), X-ray diffractometer (XRD), scanning electron microscopy(SEM), transmission electron microscopy (TEM), hardness test and uniaxial tensile test at room temperature, respectively. The samples were prepared by hot-extrusion after casting. The results showed that the as-cast Sn-containing alloys consisted of α-Mg, Mg₇Zn_3, Mn and Mg₂Sn phases. T6 treatments could obviously improve the strengths of the as-extruded samples, and the double aged samples exhibited enhanced age-hardening response at an earlier stage compared to the single aged ones. Among them, the 4 wt.% Sn containing sample with double peak aging after solution treatment had the highest strengths and moderate elongation. Microstructure characterization indicated that the high-strengths of the peak aged alloys were mainly determined by a synergistic effect on precipitation strengthening of β₁^′ (MgZn₂) and Mg₂Sn precipitates, and the precipitates after double aging were finer than those after single aging

[en] Partial rolling processes at different temperatures were conducted on the fusion zone (FZ) of double-side welded Mg–3Al–1Zn alloy joints with excess weld bead. The effect of rolling reduction and rolling temperature on the microstructure, mechanical properties and fracture behavior of the joints were investigated. Results show that both the strength and elongation of the joints increase significantly with rolling reduction owing to the microstructure evolution in the FZ. Once rolling reduction exceeds a critical value (CRR), tensile fracture location will be transferred from the FZ to the substrate and the joints can achieve tensile properties roughly the same as those of the initial substrate. Rolling at a lower temperature is preferred to obtaining a weak basal texture in the FZ, for the corresponding CRR is smaller

[en] Highlights: • Thermodynamic and precipitation kinetics calculation was used to analyze aging hardening after addition of Sn. • Precipitation sequences were determined by the content of Sn element. • The microstructure of Mg_1_7Al_1_2 discontinuous precipitates were influenced by Mg_2Sn precipitates. - Abstract: The microstructure and mechanical properties of AZ80 wrought magnesium alloys with varying Sn contents (0, 1, 2 and 4 wt.%) have been studied by thermodynamic and precipitation kinetics calculation and examined using scanning electron microscopy (SEM), transmission electron microscopy (TEM), hardness test and uniaxial tensile test at room temperature in this paper. The results of thermodynamic and precipitation kinetics calculation showed that the precipitation sequences were determined by the content of Sn element. It was found that in the aging treatment of this work, Mg_1_7Al_1_2 phase precipitated sooner than Mg_2Sn phase in the alloys with less than 1.72 wt.% Sn and there was a contrary precipitation sequence of these two phases in the alloys with more than 1.72 wt.% Sn. Experimental results were in agreement with those of calculation. According to SEM and TEM observation, Sn promoted precipitation of Mg_1_7Al_1_2 on aging temperature, however the preferential Mg_2Sn phase suppressed discontinuous Mg_1_7Al_1_2 precipitates by hindering the growth of these in their growth direction. AZ80 with 1–2 wt.% Sn as-aged alloys exhibited outstanding mechanical property that UTS, YS and EL were ∼420 MPa, ∼290 MPa and ∼5%, respectively

[en] The as-rolled AZ31 Mg alloy sheet was welded by double-sided tungsten inert gas (TIG) welding, followed by annealing and hot rolling with different reduction. The influence of the rolling reduction on the microstructure, tensile properties and microhardness of the specimens was examined. Results showed that the microstructure of the weld fusion zone (FZ) and heat affected zone (HAZ) became more and more consistent with that of the base metal (BM) as the hot rolling reduction increased. The β-Mg₁₇Al₁₂ phases in the FZ dissolved gradually during hot rolling. Both the weld joint and BM were strengthened by hot rolling; the tensile strength of weld joint and BM were closest when the rolling reduction was 27%. The microhardness of the welded sheet increased with rolling reduction

[en] The microstructure evolution and mechanical properties of AZ31 magnesium alloy during semi-solid extrusion (SSE) has been studied and compared with traditional extrusion (TE). The results show that non-equilibrium crystallization and plastic deformation occur simultaneously in the semi-solid extrusion process. Throughout the SSE process, the nucleation rate of new fine grains is significantly higher than that of the TE, which is the result of combined nucleation of crystallization and dynamic recrystallization. Twinning can be hardly activated during the SSE process, because the restraint between deformed grains is largely reduced due to the good fluidity of the semi-solid Mg alloy. The Mg alloys extruded by the SSE is characterized for homogeneous microstructure with fine grain size, weakened texture and improved mechanical properties.