A (Al₁₁La₃+Al₂O₃)/Al composite was prepared by powder metallurgy process through the in-situ reaction of Al-La₂O₃. It was found that the high energy ball milling can promote the in-situ reaction and facilitate high-temperature sintering, thus a sufficient in-situ reaction between Al and La₂O₃ was achieved, and a dense and defect-free material was obtained. The microstructure analysis showed that micro-Al₁₁La₃ and nano-Al₂O₃ particles were uniformly dispersed in the matrix. The room-temperature tensile strength of the composite reached 328 MPa, the elongation was 10.5%, the tensile strength at 350℃ reached 119 MPa, and the elongation was 10.2%. Compared with the traditional Al-Cu-Mg-Ag and Al-Si-Cu-Mg heat-resistant aluminum alloys, the high-temperature tensile strength of the (Al₁₁La₃+Al₂O₃)/Al composite was enhanced by about 20%. The strengthening effect at room temperature may come mainly from the dislocation strengthening and load-transfer strengthening effect of Al₁₁La₃ and Al₂O₃, while the strengthening effect at high temperature may be ascribed to the grain boundary pinning effect of Al₂O₃.

Polyimide (PI) and polyvinylidene fluoride (PVDF) were dissolved in N, N-dimethylformamide (DMF) separately, and the two solutions were blended, then the blending was dropped gradually into a mixture of alcohol and pure water to generate precipitated floccules. Finally, the floccule was collected and dried, then hot-pressed to prepare the all-organic composite film of thermoplastic polyimide/polyvinylidene fluoride. The compatibility, crystallization behavior, and energy storage performance of the composite film were characterized by means of SEM, XRD, DSC, dielectric and ferroelectric tests. It follows that the PI/PVDF film prepared by this method is compact and uniform with only few voids. The addition of PI promotes the formation of γ-phase, but has little effect on the breakdown performance of PVDF film, while obviously improves its energy storage performance. When the addition amount of PI is 5%, a high energy storage density of 6.52 J·cm^-3 can be generated by an electric field of 300 MV·m^-1, which is about 1.4 times that of pure PVDF film in the same condition.

The two large surfaces of Cu-4.5%Al alloy sheet of 4mm in thickness was simultaneous sujected to mechanical grinding treatment at liquid nitrogen temperature for 2 min, then a Cu-Al alloy sandwich was acquired with two sides of gradient structure layer of ~250 μm in thickness, for which there should exist a negative gradient versus the distance to the alloy center in defect density of dislocations, faults, nano-twins etc. in the two surface layers. The evolution of shear bands of the sandwich alloy during tensile process was investigated by digital image correlation method. The results show that the locally concentrating of strain can be avoided by two-sided constrained gradient structure of the sandwich material, the uniform distribution of stress and strain may be beneficial to avoid the premature of plastic instability till the necking stage, in other word, a better work hardening ability can be maintained.

A novel nanofibrous absorber composed of FeCo alloy and SnO₂ has been synthesized through electrospinning coupled with hydrogen reduction. Its structure, morphology, magnetic and electromagnetic properties were characterized by X-ray diffractometer, scanning electron microscopy, vibrating sample magnetometer and vector network analyzer, and the effect of the molar ratio of SnO₂ to FeCo on the microwave absorption properties of the composite nanofibers is investigated. It was found that the introduction of an appropriate amount of SnO₂ can significantly enhance the microwave absorption properties of FeCo/SnO₂ nanofibers as a result of the improved impedance matching, the good synergistic effect between magnetic FeCo alloy and dielectric SnO₂, and the enhanced interfacial polarization relaxation, as well as the multiple scattering and reflection caused by the 3D network structure formed by the nanofibers. When the SnO₂ molar content in the nanofibers is 20% the minimal reflection loss value of -40.2 dB is obtained at 10.95 GHz for a thin coating of 1.4 mm, and the corresponding effective absorption bandwidth with reflection loss lower than -10.0 dB is about 2.64 GHz (9.75-12.39 GHz). Moreover, when the coating thickness is reduced to 1.0 mm, the effective absorption bandwidth reaches 4.16 GHz (13.84~18.00 GHz). These excellent absorbing performances suggest that the FeCo/SnO₂ composite nanofibers designed here could be a promising electromagnetic absorbing material with a strong and broad absorption band.

The solidification behavior of a Sn-20% (mass fraction) Ni peritectic alloy in conditions of ordinary gravity and microgravity were comparatively studied by using a 50-meter-high drop tube. The solidified microstructure of the alloy was observed by optical metalloscopy (OM), the percentages of residual primary phase, peritectic phase and final solidification phase in the samples were counted by IPP (Image Pro Plus) software, and the solute distribution and phase composition in the samples were determined by means of energy dispersive spectrometer (EDS) and X-ray diffractometer (XRD). The results show that the solidification process of Sn-20% Ni may involve the primary phase nucleation at solid-liquid interface front, dendrite growth and peritectic reaction. Gravity has significant effect on both the primary phase formation and peritectic reaction, resulting in significant difference in the partition and distribution of phases as well as the distribution of alloying elements obtained in the conditions of microgravity and ordinary gravity respectively. The amount of residual primary phase and the total amount of residual primary phase plus peritectic phase in ordinary gravity condition is always lower than those in microgravity condition, while the quantity of peritectic phase is always higher. In addition, the distribution of solute element in the samples are basically consistent with those of the total amount of residual primary phase plus peritectic phase. These results indicate that the microgravity environment is favorable to the formation and growth of primary phase of the Sn-20% Ni alloy, in the contrary, the gravity environment promotes peritectic reaction, which is related to buoyancy convection and crystal nucleus deposition induced by gravity.

The 7075 Al-alloy was subjected to T6 aging treatment at deep cryogenic temperature (DCT-T6) via soaking in liquified nitrogen, and its precipitation phase, dislocation density and tensile properties were assessed by means of TEM, SEM and tensile testing techniques. The results show that the DCT-T6 could increase the density of intra-grain precipitated phases, reduce the size of precipitated phase, increase the dislocation density and the formation of sub-grain, in comparison with the conventional T6 treatment. In the range of 3~6 h, with the increase of soaking time, the η' phase density increases and then decreases, and the inflection point is 4 h; the size of grain boundary precipitated phase (GBP) and the phase spacing, the number of linear defects, η phase density, dislocation density and the number of sub-grains all increase constantly; the tensile strength of the alloy increases and then decreases, and the elongation constantly decrease. When the soaking time was 4 h, the tensile strength of the alloy reached a maximum value of 645 MPa, which was 13.1% higher than that of the T6 alloy; when the soaking time was 3 h, the elongation of the alloy reached a maximum value of 13%, which was 44.4% higher than that of the T6 alloy.

Double-layer carbon coated Na₃V₂(PO₄)₃ (NVP), as cathode material for sodium-ion batteries, was successfully synthesized by ultrasonic-assisted solution combustion synthesis, and its structure, morphology and electrochemical properties were investigated. The results show that the surface of NVP particles is firstly coated with an amorphous hard carbon layer, subsequently with a graphene layer. When the graphene content is 5.0%, the carbon-coated NVP composite exhibits excellent electrochemical properties. It delivers an initial discharge capacity of 117 mAh·g^–1 at 1 C, and retains 79% of the initial capacity after 300 cycles. Even at 10 C, it still maintains a discharge capacity as high as 100 mAh·g^–1. The significant improvement of the sodium storage performance can be ascribed to the special structure of homogeneous double-layer carbon coating, which can act as a 3-dimentional network as electron pathway.

Three kinds of GH4169 alloy ingot were made via vacuum induction melt-casting method with metal block chromium of different quality (i.e. high purity chromium, common chromium and micro-carbon ferrochrome) as raw materials. The characteristics of inclusions in superalloy ingots were investigated by optical microscope (OM) and scanning electron microscope (SEM), and their formation mechanism are analyzed by JMatPro software. It is found that the content of N, P, S and Mn in the ingots decreases with the increase of chromium purity. The types of inclusions in the ingots change to single oxides from oxides, carbonitrides and composite inclusions. The content of carbonitrides and composite inclusions gradually decreases with increasing chromium purity.

The thermo-mechanical fatigue behavior of GH4169 alloy was investigated via MTS809 fatigue testing machine by applied multiple test loads at different temperature range. It is found that the hysteresis loops of GH4169 alloy have obvious asymmetry in tension and compression under thermo-mechanical condition. The material bears compressive stress when the mechanical strain amplitude in phase, whilst tensile stress for out of phase. The tensile stress is the main cause affecting the fatigue life. The average stress relaxation occurs at higher strain amplitude. In the high temperature half cycle, the alloy softens first and then becomes stable. In the low temperature half cycle, the alloy tends to be stable.

Butt welding joints of 2195 and 2219 Al-alloy plates were prepared by tungsten argon arc welding (TIG) and variable polarity plasma arc welding (VPPA) respectively while applying argon shielding and no argon shielding, and then the influence of processing parameters on the microstructure of the welding joints were assessed by means of metallographic microscope, scanning electron microscope (SEM), hardness tester and tensile testing machine. The results show that no macroscopic thermal cracks were detected in the welding seam of the joints prepared by TIG and VPPA welding processes, however the VPPA welding process results in narrower welding seam due to its high speed processing with low heat input whilst high energy density. The main precipitates near the fusion line of the weld joints are θ-phase, while eutectic microstructure of α-Al and θ-phase exists in the weld seam. No local softening existed in welded joints prepared by TIG and VPPA with argon shielding, correspondingly, the hardness of the weld seam is more or less the same as that of the base metal of 2219 Al-alloy side, and the welding joints prepared by TIG possess higher tensile strength.