The mechanical properties of ER8 steel for wheel rim were studied at -40℃, -20℃, 0℃ and 25℃ (room temperature) respectively, while the microstructure and fractured surface of the steel were characterized by means of laser confocal microscopy, field emission scanning electron microscopy (SEM). Results show that the tensile- and yield-strength increase linearly with the decreasing temperature, i.e. the increments of which reach 5.8% and 7.1% respectively at -40℃, in comparison to those at room temperature, correspondingly the plasticity index (elongation and cross section shrinkage) decreases by about 2%; The impact toughness of the steel for wheel rim is very sensitive to temperature, the impact toughness of the steel reduces rapidly with the decreasing temperature, and the impact energy reduces by 60% at -40℃ in comparison to that at ambient temperature; The fatigue life of the steel at -40 is higher than that at room temperature. At -40℃, the size of secondary cracks in the fatigue source and crack propagation zone is smaller than those at room temperature, the fatigue crack critical size a_c is about 3.2 mm at room temperature, while it is about 4 mm at -40℃。

Layered films of Cu₂ZnSnS₄ (CZTS) thin films were prepared by sequentially and cyclically sputtering three targets of ZnS, CuS and SnS, which then were annealing at 360℃ for 30 min, afterwards they were sulfurized in a graphite box with 0.5 g sulfur powder at 600℃ for desired period of time. For three cycles of sputtering (T3), the prepared CZTS thin layered film is dense and compact with smooth surface, uniform crystal-grain size and a band gap of 1.5 eV. The solar cell assembled by the T3 ZTS film has better performance with the following parameters: the open circuit voltage 623 mV and the short-circuit current density 11.79 mA/cm², respectively. Correspondingly, the photoelectric conversion efficiency could reach 2.93%.

Fracture toughness tests of the matrix and weld joint of 316LN stainless steel (SS) were carried out, while the acoustic emission (AE) signals were monitored simultaneously during the fracture process in real time. Then the AE signals were classified. The results show that the fracture of the matrix of 316LN SS and the weld joint was ductile ones, and the plasticity of the matrix was better than that of the weld joint. The fracture process could be divided into five stages including the crack tip opening stage, the elastic deformation stage, the plastic deformation stage, the crack initiation stage and the stable crack propagation stage. Moreover, the correlation analyses of rise time and duration of the AE signals indicated that the fracture processes could be classified into several categories, which was available for distinguishing the noise signal and effective fracture signal within the AE signal spectrum.

The influence of quench rate after solution treatment on the exfoliation corrosion resistance of the rolled 7020 Al-alloy plate was studied by means of standard exfoliation corrosion immersion tests and electrochemical impedance spectroscope (EIS) technique, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) technique and scanning transmission electron microscopy (STEM). Results showed that the exfoliation corrosion resistance of this alloy plate decreases with quench rate decreasing from 1800℃/min to 38℃/min. Correspondingly, the corrosion-ranking of the alloy degrades from EA to EB+, while the maximum corrosion depth increases from 388 μm to 570 μm. The relevant mechanism was discussed based on the effect of quench rate on the changes in the size, the number, the spacing and the microchemistry of grain boundary precipitates as well as the width of precipitate free zone.

Effect of Mo-content on the microstructure and properties of AISI D2 tool steel has been studied by means of OM, SEM, TEM, XRD and EDS. Results show that with the increasing Mo-content, the grain size of the steel decreased, while the amount of eutectic carbides increased, and the morphology of which changed from rod-like to fish bone-like and block-like. The thermal stability of the fish bone-like and block-like carbides is higher than that of the rod-like ones, thereby, they are difficult to dissolve and spheroidize during heating process. This fact may result in the decrease in solubility of alloying elements after quenching, and the decrease in hardness after tempering. The optimum Mo content is between 0.9% and 1.1%, correspondingly, the hardness of the tempered D2 steel is 61 HRC, and the impact toughness reaches about 20 J/cm².

Three quaternary Mg-alloys of Mg-6Gd-4Y-xZn (x=1, 2, 3, mass fraction, %) were prepared, while all the alloys contained strengthened phases of long period stacking ordered (LPSO) structure. The effect of Zn-concentration on the microstructure and mechanical property of the alloys, as well as the formation and evolution of LPSO phases in the alloys and their strengthening mechanism were also studied. Results show that the as-cast microstructure of the Mg-6Gd-4Y-3Zn alloy consists of α-Mg matrix and Mg₁₂Y₁Zn₁ phase which presents 18R long period staking ordered (18R-LPSO) structure. The Mg₂₄(GdYZn)₅ eutectic was observed in the as cast microstructure of the alloys with lower Zn additions. After homogenizing annealing, the microstructure of all the quaternary alloys consists of a-Mg matrix, 18R-LPSO- and 14H-LPSO-phases. With the increase of Zn content, the volume fraction of 18R-LPSO phase increases and the lamellae of the 14H-LPSO phase in the matrix are thickened. Both T6- and T5-treatments result in the β' precipitation. The tensile strength of Mg-6Gd-4Y-xZn alloys decreases with the increase of Zn content. The ideal strengthening effect can be achieved by the coexistence of 18R-LPSO phase, small and well distributed precipitates of 14H-LPSO phase and β' precipitates in the microstructure.

Nanostructure of CoFe_2-xCe_xO₄(x=0,0.1,0.2,0.3,0.4) was synthesized by sol-gel coupled with self-propagating method. The prepared nanostructures were characterized by means of XRD, EDS, FT-IR, SEM, TEM and PNA in terms of phase constituents, morphology and electromagnetic properties. Peculiarly, the influence of the amount of Ce³⁺ on absorbing properties was investigated. Results show that the prepared CoFe₂O₄ has spinel structure. The average diameter of particles is about 70 nm. The microwave absorption ability of the CoFe_2-xCe_xO₄ is greatly improved in the frequency domain of 0~6 GHz, in comparison to the pure CoFe₂O₄. When the Ce³⁺ content is 0.3 it has the best wave-absorbing property at 5030 MHz, of which the maximum absorption can reach -27.6 dB and within a bandwidth of 1.6 GHz, its absorption is above -5 dB.

The evolution of microstructure and texture at different temperatures and its effect on room temperature strength in Ti60 Ti-alloy plates were investigated in the present work. There was no perceivable change of the microstructure or texture after heat treatment at 700?C compared with those of the as-rolled plate. In α+β and β phase regions equiaxed primary α grains shrank and ultimately transformed to secondary α phase, and T-type texture was replaced by a new type of texture with temperature increasing. It was indicated that whether new texture formed or not was significantly affected by the percentage of primary α phase during α→β→α phase transformation: by high percentage, the primary α phase strongly induced the secondary α phase to be with the similar orientation, thereby nearly no change of the texture; by low or zero percentage, part of the formed secondary α phase with new orientation, which was hardly affected by the primary α phase and was inferred as results of α variants selection dominated by texture of β grains formed during rolling at high temperature. Room temperature strength was mainly affected by the substructure: heat treatment in the α phase region didn't eliminate the substructure, the room temperature strength is comparable to that of the as-rolled plates; heat treatment in/above α+β phase field eliminated the substructure, resulting in large reduction of room temperature strength compared with the as-rolled plates. After eliminating the substructure, the room temperature strength was impacted by the microstructure: similar room temperature strength of plates heat treated in low and high α+β phase region is related to the limited effect of the percentage of equiaxed primary α phase on the strength; the room temperature strength decreased after heat treatment in β phase region, and the decrease amplitude in certain direction was remarkably affected by texture. The degree of room temperature anisotropy was influenced by the texture and substructure: higher strength exhibited along the crystallographic c axis; while the substructure weakened the influence of the texture on anisotropy, resulting in stronger anisotropy in plates heat treated in/above α+β phase region.

Silicon-containing aryl propargyl ether of bisphenol A (SAPE-BA) and silicon-containing aryl propargyl ether of diphenyl ether (SAPE-DPE) were synthesized and characterized. Then they were used to modify the silicon-containing arylacetylene resin (PSA) respectively by blend process. The modified PSA resins (PSA/SAPE-BA and PSA/SAPE-DPE) were reinforced with T300 carbon fabric to form composites of PSA resins by hot press. The processability, thermal stability, and the mechanical properties of the modified resins and their composites were further investigated. Results show that the modified PSA resins have not only good processing performance, but also high heat-resistance. In comparison with the cured simple PSA resin, the temperature at which 5% mass loss (T_d5) of the two cured modified PSA resins in nitrogen were higher than 550℃ and 590℃, respectively, and the T_g of the cured modified PSA resins were higher than 500℃; The flexural strength of the cured modified resins, PSA/SAPE-BA and PSA/SAPE-DPE increased by 78.3% and 54.2%, respectively. While in comparison with the composite of T300 carbon fabric (T300CF) reinforced simple PSA, the flexural strength and interlayer shear strength (ILSS) of the composite of T300 carbon fabric (T300CF) reinforced PSA/SAPE-BA resin increased by 38.4% and 33.5%, and the flexural strength and ILSS of the composite of T300CF reinforced PSA/SAPE-DPE resin increased by 23.4% and 21.8%, respectively.

Sheets of Al-alloys 5083 and 6061 of 6 mm in thickness were subjected to friction stir welding (FSW) with different welding parameters. The effect of welding parameters on the microstructure and mechanical property of the FSW joints were investigated. Results show that FSW joints with high quality could be produced by controlling welding parameters, and a high joint strength coefficient of 85% was obtained. Dynamic recrystallization took place in the nugget zones (NZs) with fine and equiaxed grains generated, and the grain size increased with the increasing rotation rate; usually the grain size of 5083 Al in the NZ was smaller than that of 6061Al. The heat-affected zones (HAZ) of 6061 Al side were the low hardness zones in all of the FSW joints, and the value of low hardness increased with the increasing rotation rate. It is found that the fracture paths corresponded well with the lowest hardness distribution profiles in the joints and the ultimate tensile strength increased with the increasing of the rotation rate.