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Gravity-pouring of a TiAlNb alloy from an induction skull melting (ISM) furnace into a ceramic shell mould was carried out. The microstructure and gas defects were examined by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) analysis. Results show that the oxide films exist in the bubbles and porosity, and act as defects' heterogeneous nucleation sites. The bubbles consist of entrained and precipitable ones, while the porosity consist of layer and centerline ones. The diameter of casting bars, mould temperature and the partial pressure of argon influence the formation of gas defects.

In the present work, laser welding with filler wire was successfully applied to joining a new-type Al–Mg alloy. Welding parameters of laser power, welding speed and wire feed rate were carefully selected with the objective of producing a weld joint with the minimum weld bead width and the fusion zone area. Taguchi approach was used as a statistical design of experimental technique for optimizing the selected welding parameters. From the experimental results, it is found that the effect of welding parameters on the welding quality decreased in the order of welding speed, wire feed rate, and laser power. The optimal combination of welding parameters is the laser power of 2.4 kW, welding speed of 3 m/min and the wire feed rate of 2 m/min. Verification experiments have also been conducted to validate the optimized parameters.

Samples of Al-Mg-Mn-Zr-Er alloys were welded by the method of TIG welding. Microstructures of base metal and welded zones were analyzed by optical microscopy (OM), electron probe micro-analyzer (EPMA) and transmission electron microscopy (TEM). Particular emphasis was laid on the existence form of Er and its effect on the microstructure and the phase composition of the fusion zone. Results reveal that the trace rare earth element Er mainly exists in the form of primary and secondary Al3Er phase, which play significant roles of refining and strengthening the fusion zone. A characteristic Equiaxed Zone (EQZ) is obtained beside the fusion boundary between the partially melted zone and the fusion zone (FZ) due to the addition of Er.

A facile method to control the morphology of FeNi3 nanoparticles by solution reduction reaction is presented. The spherical to platelet FeNi3 particles were obtained by changing pH from 11.5 to12.5 with 0.16 mol/L of hydrazine under ultrasound irradiation, with the ratio of Fe2+ to Ni2+ as 1:3. The amount of hydrazine had little influence on the morphology of the particles. The saturation magnetization (Ms) and coercive force (Hc) of the platelet particles were 59 emu/g and 120 Oe, respectively. The real part μ’ of the permeability of the platelet particles was about 2.43–2.71 and was frequency-independent in the range of 0.1–1.0 GHz. The imaginary part (μ”) of the particles showed increase from 0.04 to 2.14 within the same frequency range.

The hot deformation behavior of an Al–5.7 wt.%Mg alloy with erbium was studied by compressive deformation tests in the strain rate range of 0.001–10 s −1 and temperature range of 300–500 °C. The constitutive equations were presented considering the values of A and β as a function of strain in the exponential function form. The error of predicted and measured data was less than 9%. Dynamic recrystallization was restrained by precipitate with Er and dynamic recovery dominated in the hot deformation. The mechanism of dynamic recovery was dislocation movement and the development of microstructure during deformation can be characterized by the Z parameter, and then the relationship between subgrains and deformation parameters have been also established.

This research focused on the synthesis of ultrafine Ni–Co composite powder prepared using a freeze-drying technique. In the process of freeze-drying, the Ni–Co powder was prepared by freeze-drying the precursor from simple NiC 2 O 4 and CoC 2 O 4 powders. Thermal decomposition of the amorphous freeze-dried precursor powder produced the ultrafine Ni–Co composite powder. To assure process control and product characterization, the freeze-dried precursor and the final products were analyzed by means of XRD, SEM, TEM, and IR. The results showed that the freeze-dried powder existed in a non-hygroscopic and non-crystalline state. The final product of the experiments was a Ni–Co composite powder, which existed in the form of a single crystalline state and represented fine, homogeneous, spherical particles, reaching a size range of approximately 40–70 nm. The freeze-dried powder was composed of [Ni(NH 3 ) 6 ] 2+ and [Co(NH 3 ) 6 ] 3+ .

Nanoparticles of cerium oxide were prepared by common precipitation method using cerium nitrate solution and ammonia reagent. Cerium oxide particles with different morphologies were synthesized through adjusting pH values of the solution. TEM and BET results showed that spherical crystal was gained in acid solution, with the specific surface of 148.1944 m2·g−1. The cerium oxide appeared in the form of spherical and rod-like grains under neutral condition, and the specific surface changed to 114.7975 m2·g−1. Moreover, in alkaline solution, cerium oxide powders were exhibited in rod-like form with the specific surface of 106.2465 m2·g−1. Precipitation formation mechanism of different morphologies was also discussed, which followed decomposition precipitation mechanism and topology reaction mechanism in acid and alkaline solution, respectively.