3-D morphology of the degenerate ferrite formed below the bay of the TTT diagram in an Fe-0.28C-3.0Mo (mass fraction, %) steel has been revealed by utilizing serial sectioning in conjunction with computer-aided reconstruction and visualization. The degenerate ferrite is initially formed at prior austenite boundary and then grows toward grain interior rather than along the grain boundary. The degenerate ferrite consists of rod-like subunits, each several micron in length and 1-2 μm in diameter. The peculiar morphology of ferrite may be attributed to the repeated nucleation, growth and coalescence of the adjacent ferrite crystals.

An analytical micromechanical method, based on the lamellar microstructure and dislocation slip and twinning deformation mechanisms of polysynthetically twinning (PST) crystal, is used to investigate the variation of the yielding stress as function of angle θ between the load axis and the lamellar boundaries for a PST crystal. The sub-domain microstructure of the γ-TiAl-based alloy, PST crystal , slip system phase in PST crystal and the difference of CRSS in ordinary slip and true twinning have been considered in this paper. The results demonstrated that yielding stress relations on loading angle with respect to the microstructure and in soft mode of deformation, which is determined by ordinary dislocation or superdislocation slip systems in γ phase, shear deformation is parallel to the lamellar boundaries; in hard mode of deformation, shear deformation crosses the lamellar boundaries, which is controlled by twinning in the γ phase. In addition, the predicted yield stress values of PST crystals for three loading angles θ=45°, 0°and 90°have the relation as σy(45°)<σy(0°)}<σy(90°). Furthermore, the active slip and twinning systems have also been analyzed systematically.

When phosphorus content is below 0.040%, no obvious effect on the tensile properties of GH761 alloy at room temperature and 650℃ was observed. However, phosphorus influenced the stress rupture properties of GH761 alloy greatly. The peak value of the rupture life at 650 ℃ and 637 MPa appeared at 0.023% phosphorus. At the point, the life was longer than 970 h, more than 3 times of that when the phosphorus content is 0.0007%. Phosphorus can prolong the rupture life of GH761 alloy by inhibiting the dislocation glide, increasing the intergranular precipitation and blocking the diffusion of oxygen along gain boundaries. However, excessive addition of phosphorus lowered the grain boundary strength by deteriorating the grain boundary precipitation and causing the precipitation of η-Ni3Ti, which shortened the rupture life of GH761 alloy.

A creep test was conducted on a Gleeble-1500 thermal simulator for monitoring the aging procedure of Cu-Nb ultra-low carbon steels with different contents of copper. The result indicated that during creep testing the occurrence of precipitation could make a plateau on the creep curve. The left- and right-hand ending points of the plateau can be defined as the precipitation start (Ps) and finish (Pf) times, respectively. The Pf is in coincidence with the peak time (tp) from hardness curve. The precipitation-time-temperature (PTT) diagrams of two steels were obtained.

A constitutive equation was established based on stress-strain curves of S34MnV at different strain rates and high temperatures. The coupling of thermal-mechanical process in bending large marine crankthrow was simulated by using ABAQUS code. From the simulation results, the strain-stress field and temperature field in the forging process were obtained. In order to analyze the mechanism of metal flow of crankthrow, the evolutions of the hydrostatic pressure and the surface tensile/compressive stress of typical positions on the crankthrow were investigated. The simulated defect positions, such as the “slim waist”, crack and“horn mouth”etc, as well as the final shape and size of the crankthrow agree well with the experimental ones. Furthermore, an improved suggestion was given, which could be helpful to optimize the forging parameters.

The microstructure and mechanical properties of retrogression and retrogression reaging (RRA) treated Al-Zn-Mg-Cu aluminum alloys with 11.64%Zn (mass fraction) prepared by spray deposited technology were studied using transmission electron microscopy (TEM) and MTS-810 materials test system. The results showed that with the increase of retrogression temperature and retrogression time, the ultimate tension strength (UTS) of the alloy were declined and that of RRA treated alloy exhibited a parabola feature. The UTS of the alloy treated under 120 ℃, 24 h + 180 ℃, 30 min + 120 ℃, 24 h is superior to that of peak aging alloy, which is an ideal RRA treatment system for spray deposited Al-Zn-Mg-Cu alloys.

SEM in situ observations for the effects of inclusions on the fatigue crack initiation and propagation behaviors of super strength steel indicate that the inclusion size and shape affect not only on the fatigue crack initiation location but also on the crack growth behavior. At the same time, the effects of inclusions on the fatigue crack initiation are discussed by finite element method (FEM) analysis. The critical size of inclusion in low cyclic fatigue crack propagation is proposed and the influence of fatigue crack growth rate is estimated.

70%Si-Al alloy as a novel electronics package material was prepared by spray deposition. HIP technique was adopted in order to density the billet. The prepared 70%Si-Al alloy has a microstructure with fine silicon particles (10-20 μm in diameter) well dispersed in the matrix. The alloy shows excellent comprehensive properties, especially a lower thermal expansion coefficient and a lower density compared with the traditional electronics packaging materials. After HIP, The comprehensive properties of the 70%Si-Al alloy can be further enhanced. The alloy can be machined with the traditional cutting tools and applied as the packaging materials for the power IC, microwave electronic parts and integrate circuit blocks.

The cathode material for lithium batteries Li1.15-xNi1/3Co1/3Mn1/3O2+δ has been synthesized by sol-gel technique. The effects of synthesizing temperature on the structure, micro-morphology and electrochemical properties of these materials were investigated using X-ray diffraction, scanning electron microscopy and charge-discharge cycling tests. The material synthesized at 600 ℃ has a hexagonal layered structure. The intensity of the diffraction peaks and the particle size of the material synthesized at 920-980 ℃ increased with synthesizing temperature. The ratio values of I_003/I_104 and unit cell volume of the material synthesized at 950 ℃ are larger than those of the material synthesized at 920 and 980 ℃. The maximum charge/discharge capacity and the minimum electrode polarization were obtained for the material synthesized at 950 ℃, which has the initial discharge capacity of 180 mA•h/g in the range of 2.5-4.5 V at a specific current of 28 mA/g.

Large amount of sulphides were synthesized safely by a temperature gradient method using metals and sublimed sulfur as the raw materials, and a sulphur concentration cell was developed by using MgS+1.5%ZrS2 as solid electrolyte and Mo+MoS2 as reference electrode. The sulphur content in carbon--saturated liquid iron (oxygen activity degreea[O] ≤2×10 -6) at 1623 K was determined by using the prepared sulphur concentration cell. The gas leakage and splitting crack were solved by optimizing the structure of solid electrolyte tubes, hydration and oxidation of the sulphide were also avoided by using special processes. The results showed that the sulphur concentration cell could be continuously used with stable signals and good reproducibility.

Ceramic coating on the surface of die casting Al alloy ADC12 with high Si content has been prepared by micro-arc oxidization (MAO) in an electrolyte containing Na2SiO3 and Na3PO4 as its major compositions at constant current density. The testing results of hardness and corrosion protection indicate that the obtained ceramic coating has relatively high microhardness (HV up to 1430) and could provide effective protection to substrate. Eddy currency thickness measurement and SEM micrographs manifest that the ceramic coating consists of a double-layer structure and its thickness is relatively even. EDX and XRD analyses reveal that the main elements in the coating are O, Al, Si as well as P, and that the main phases are γ-Al2O3, α-Al2O3. In addition small amounts of χ-Al2O3, θ-Al2O3 and Al2SiO5 are also detected.

Based on the amount of preparation work of hollow fibrous nickel plaque in laboratory, ANN-GA programs on computer network which were designed by our group was used in optimizing the process parameters and looking for the optimized condition. The optimized condition was that the content of nickel fiber was 97%, sintering temperature 1275 K and holding time 20 min, PVB 5%, PP 3.5% and Ni(OH)2 1%. Under the optimized condition the satisfactory plaque with almost 87% porosity has been carried out and every single factor effect on the plaque porosity during preparing the plaque was analyzed and predicted with computer. These results coincided with those obtained by other researchers' experiments.

Using spark plasma sintering technique, a bulk Al90Mn9Ce1 alloy, reinforced by quasicrystal particles, has been sintered under the pressure of 50 MPa at 400 ℃. The density and the compressive strength of the as-prepared bulk alloy are above 98% and 1000 MPa, respectively. It has been found that during the spark plasma sintering process, under the condition of large current, short sintering time and lower sintering temperature, the metastable icosahedron quasicrystal phase in primary powder particles is kept. And the strong discharge plasma among particles can decompose or break the oxide film on the primary powder's surface, resulting in the increment of their combination strength. So the as-prepared bulk alloy possesses high density and ultra-high strength.

The microstructure of SiC particle reinforced Al-7.0%Si (mass fraction) composite prepared by stir casting was simulated by a modified cellular automaton method coupled with finite difference method and two-dimensional models under normal solidification condition including macro heat transfer, nucleation, equiaxed dendrite growth and particle pushing. The effects of different casting processes on composite microstructure and particle distribution were analyzed. The simulated results can clearly show the evolution of the microstructure of composite and particle clustering phenomena caused by particle pushing. The simulated results are in good agreement with the experimental results. Grain size is smaller and particle distribution is more uniform for metal mould casting than sand mould casting.