The surface relief, especially the double-tilt surface relief, associated with diffusion controlled phase transformations in some alloys, has not been well understood so far. A bottleneck is the absence of a strict and systematic measurement method. The present paper introduced a new measurement method based on the EBSD and AFM technology. Various crystallographic features were quantitatively determined by this method, including the orientation relationship (OR),the orientation of the habit plane (IO), the displacement vector inducing the surface relief and the maximum relief angle. The OR and IO were consistently in agreement with the calculated results from the O-line method. However understanding of the displacement vector and unusual large relief angle needs further study.

Multi-walled boron nitride nanotubes (BNNTs) synthesized by chemical vapor deposition were revealed to possess a definite stacking order (dominant r-BN stacking) and preferential zigzag chirality. Based on the microscopic characters of BNNTs, structure models were built and computer simulations of HRTEM images were carried out. It was found that HRTEM images of BNNTs with r-BN stacking are sensitive to the wall number, tubes diameter and angle of observations. Appearance of moire fringe on the HRTEM image of tube body was proposed to judge the existance of r-BN stacking.

Based on the generalized gradient approximation (GGA) of density function and the full-potential linearized augmented plane wave (FLAPW) method, the equilibrium structure and density of states were calculated for the primary solid solution phase α-LaN5H0.5 and the intermediate phase β-LaNi5H3. In the α-phase region, 12n site is the most stable position in five nonequivalent interstices; with increasing H atoms the cell parameter a axis increases, while the c axis is constant. In the α→β region, with increasing H atoms a large increase in the a$ axis and a relatively small increase in the c axis are concluded. The charge density and density of states are also calculated for the intermediate phase.

A mathematical model for the segregation formation in channel during solidification process of binary alloys has been built and a set of expressions coupling the temperature and solid fraction with enthalpy is determined. The formation position and growth direction of the segregation during the horizontal solidification of NH4Cl-H2O with hypoeutectic and hypereutectic compositions are numerically studied based on the experiment. The simulation results show that the segregation originates from the mushy zone and the solute-rich liquid flows from mush into liquid. In order to supply the mass equilibrium in the channels,the fresher liquid may penetrate via the mushy zone from pure liquid region. The flow direction of solute-rich liquid in mush depends on its density. Because of the lower density of the rejected solute during the horizontal solidification of NH4Cl-70%H2O, channels grow slantways and upwards and A type segregates form in the upper region of mush. While the density of the rejected solute during the horizontal solidification of NH4Cl-90%H2O, channels grow slantways and downwards in the lower region of mush.

Based on the population dynamic method a model has been developed to describe the solidification process and the thermal histories of gas-atomized droplets. The model is coupled with the droplets' heat transfer controlling equation and the droplets' motion controlling equation, and used in Cu-13.5%Sn (mass fraction) alloy. The effects of the droplet size, the initial gas velocity, the superheat of the melt and the wetting angle between the primary phase and the catalyzing substrate for heterogeneous nucleation on droplet solidification behaviors were discussed.

The effects of carbon equivalent and inoculation on solidification process of gray cast iron were studied by thermal analysis experiments and pouring experiments of gray iron castings. Based on the dynamic expansion and contraction accumulation method, a shrinkage prediction model of gray cast iron was developed, in which the pouring temperature, carbon equivalent and inoculation were comprehensively considered. Besides, all the volume variations during solidification process, such as the contraction of melt, the contraction or expansion of primary graphite or austenite and eutectic phase, were taken into consideration during computation. A numerical simulation system especially for the solidification process of gray iron castings was developed and used to analyze the solidification process of practical gray iron castings. The simulation results are consistent with the experimental ones.

In the sand-casting magnesium alloys Mg-5Al-0.4Zn-0.2Mn-Sr-Ti-xCa , existed α-Mg, (α + Al2Ca) eutectic and Mg17Al12 when x=0.37, 0.70, 0.93, 1.69, or α-Mg and (α+(Mg, Al)2Ca) eutectic when x=2.93. With increasing x, the room temperature mechanical properties (σb, δ) of the alloys decreased, meanwhile the strength at 200 ℃ increased first and then decreased slightly, and the elongation decreased rapidly. The yield strength at 200 ℃ (σ0.2, 200 ℃) of the alloys was greatly improved with the increase of x value. DSC analysis proved that the thermal stability of Mg17Al12 phase was improved by dissolution of Ca. The grain boundary strength at 200 ℃ was improved through the formation of the Al2Ca or (Mg, Al)2Ca phases at the grain boundary. TEM analysis shows that the dislocations slip not only at the basal slip plane (0001), but also at the (10-10) prismatic slip plane and (-1-121) pyramidal slip plane at 200 ℃. The dislocation can be piled up by Al2Ca phases at the grain boundary resulting in the higher yield strength of the alloy containing Ca than those without Ca at 200 ℃.

The motion, microgravity level, and temperature of the Fe-66.7%Si (atomic fraction) droplets free falling in a drop tube filled with various inert gases under different pressures were computed. Based on the computation, the principle of choosing the proper inert gas and gas pressure was discussed in view of the gravity level and the melt cooling rate.

The orientation imaging micrographs (OIMs) in high purity aluminum rolled to 80% under room temperature and 180 ℃ were investigated using the SEM-EBSD technique. It was found that the elongated bands parallel to the rolling direction (RD) have two morphologies-the orientation concentrated and the orientation scattered, the orientations of the former mainly rotated toward β-fibre, and the area fraction of the low angle (2°---5°) boundaries in the bands with the Br-({011}＜211＞) orientation was about 10%--15% larger than those of the S-({123}＜634＞) and C-({112}＜111＞) orientations. When the rolling temperature changed from the room temperature to 180 ℃, the area fraction of the middle angle (5°---15°) boundaries was increased by about 10% because of stronger recovery during rolling at 180 ℃. The energy difference of the boundary distributions for the orientations along the β-fibre has been analyzed in term of Bishop-Hill crystal plasticity theory. It is shown that the orientations with smaller values of Taylor factor M and larger combination numbers of 5 independent active systems correspond to less boundary energy and lower angle boundary during rolling.

Hot rolled high purity aluminum sheet (99.99%) was cold rolled by cross shear rolling with different roll mismatch speed ratios (i=1.06, 1.17, 1.28). The rolled specimens were heated or annealed at different temperatures for different times. Texture distribution and microstructures of specimens were studied by X-ray diffraction technique (ODF analysis) and TEM, respectively. The results showed that the strong rotated cube texture component {100}＜011＞ formed and developed in the cross shear rolling specimen with high roll mismatch speed ratio (i=1.28). During annealing, there is a temperature threshold value for the formation and development of cube texture {001}＜100＞, which is inversely proportional to speed ratio. The cross shear rolling accelerates the recrystallization processes, which is related to deformation stored energy. The easy formation and development of cube texture {001}＜100＞ of high purity aluminum foils after cross shear rolling are analyzed based on theory of deformation and recrystallization.

The damping capacities and strengths of six alloys, Fe-13Cr-6Al, Fe-11Cr-2 (Mo, Mn or Nb)-6Al, Fe-13Cr-5.5Al-0.5Cu, and Fe-13Cr-5Al-1Cu (atomic fraction, %) were measured. The effects of annealing temperature, cooling method and substitution elements on the above two properties were discussed by optical microscope observation and internal stresses analysis. The following results were obtained: (1) The damping capacity of Fe-13Cr-6Al based alloys increases with increasing annealing temperature while strength decreases. (2) The damping capacity of furnace cooling alloys is higher than water quenched alloys while the strength of the former is lower than the latter. (3) The substitution of 0.5\%Cu decreases the interaction between dislocations and solute atoms while increases the elastic interaction between alloying atoms and base atoms, which improves both damping capacity and strength of the alloy.

The time-dependent strain cyclic characteristics and ratcheting behavior of SS304 stainless steel were studied by experiments under non-proportionally multiaxial cyclic loading and at 973 K. The effects of loading path, straining/stressing rate and holding-time at peak/valley of each cycle on cyclic softening/hardening behavior and ratcheting were discussed. It is shown from experimental results that the cyclic softening/hardening behavior and ratcheting of the material are characterized by apparent time-dependence, i.e., the cyclic deformation behaviors depend not only greatly on loading rate, but also apparently on holding-time, besides, the ratcheting behavior of the material also presents a great dependence on loading path at high temperature. Some results obtained are helpful to construct a time-dependent constitutive model of ratcheting.

Dissolution behavior of carbide TiC in Ti-60 alloys with bimodal microstructure during ageing was investigated. Solution treatment in the (α+β) phase field followed by quenching in water resulted in the precipitation of TiC carbide particles, most of which distributed in the β transformed grains and seldom at the interface of the primary α (αp) and β transformed grains or in the αp phase. The (α+β) solution-treated specimens were aged in the temperature range of 750 to 850 ℃. For the carbide precipitate in the β transformed grain, the dissolution of carbide preferentially occurs from the β phase side, leading to the irregular shape of carbide particles and the β phase-poor matrix immediately surrounding the carbide. The carbide in the αp phase dissolves at an uniformly slow rate. The mechanisms of carbide dissolution are discussed in terms of the peritectoid transformation between the β phase and carbide, the movement of dislocations and the influence of curvature.

Electrochemical impedance spectroscopy (EIS) and in situ microscopic image of T6 peak-aged AA2090 Al-Li alloys in EXCO solution were studied. The localized corrosion form of the alloy during immersion evolved from pitting through intergranular corrosion, exfoliation corrosion (EC) to post EC. EC initiated at big corrosion pits which were formed with inclusion phase as center in pitting stage. The EC blisters propagate from these big pits till the upper layer is totally lifted. EIS of the initiation stage of pitting corrosion consists of a high frequency capacitive arc and a middle-low frequency inductive arc, and the inductive arc tends to disappear when pitting corrosion starts to propagate. In the intergranular corrosion stage, the second time constant corresponding to the corroded area can hardly be distinguished in the capacitive part of the EIS. In the stages of EC propagation and post EC, their EIS consist of two capacitive arcs.

The influence of surface vertical cracks in YSZ coating on the failure mechanism of thermal barrier coatings prepared by electron beam physical vapor deposition (EB-PVD) during thermal cycling was studied. The vertical cracks occurred at the initial stage of thermal cycling testing but did not directly cause the spallation of TBC. The mesh density of vertical cracks increased following thermal cycles. Calculation by finite elements analysis showed that a larger shear stress was generated by the formation of the vertical cracks just like what in the edge of the specimen. After thermal cycling testing, when the strength of equiaxial grain regions or thermally grown oxidation layer became lower than the shear stress, the spallation occurred along the vertical crack network.

Using an industrial pulsed DC plasma chemical vapor deposition set-up, Ti-Si-C-N coatings were deposited on substrate of high speed steel. The effect of SiCl4 flow rate on chemical composition, microstructure and phases in Ti-Si-C-N coatings was explored by means of XRD, XPS, TEM and SEM. It is suggested that Ti-Si-C-N coatings are of nanocomposite structure composed of nc-Ti(C, N)/a-C/a-Si3N4. The crystalline sizes are in the range of 2-25 nm. When nitrogen content in the coatings was very low, Ti(C, N) changed to TiC and the surface morphologies of Ti-Si-C-N coatings changed from granular grains to strip-shaped grains.

Morphology, structure and chemical composition of the precipitate at Fe3Al/Q235 diffusion-bonded interface were studied by means of scanning electron microscope (SEM), energy dispersive spectrum (EDS), X-ray diffractometer (XRD) and electron probe micro-analysis (EPMA). The formation of the precipitate and the effect of technological parameters on the precipitate were also investigated. The results indicate that FeAl(Cr) was formed in the Fe3Al side of the Fe3Al/Q235 diffusion-bonded interface, which is the key to cause brittle fracture of the Fe3Al/Q235 bonded joint. The relation between the formation and growth of FeAl(Cr) and bonding parameters obeys the parabolic law, y2=3.5 (t-t0）exp[-5.6 ×10 4/(RT)]. So in order to avoid the formation of the precipitate and to ensure the performance of the Fe3Al/Q235 bonded joint, it is necessary to increase pressure for accelerating the atom diffusion at the interface with lower heating temperature and shorter bonding time.

A vision sensing system for taking and processing the image of MIG welding pool of aluminum alloy has been setup in this paper. The morphological operator which can effectively wipe off noise and cathode pulverization' area in image was used to process the image of the aluminum alloy MIG welding pool. Based on the step response experiment, the welding pool width model of dynamic process in aluminum alloy pulsed MIG welding is identified by least square method. The input parameters of the model are welding wire speed, base current and pulse duty ratio, and the output is beam width of welding pool. The influence of wire speed, base current and pulse duty ratio on welding pool width is analyzed, which provides the theoretical basis to realize the intelligent control for aluminum alloy pulsed MIG welding process.

Two atomic clusters, Cu8Zr5 and Cu6Zr5 derived from the Cu8Zr3 and Cu10Zr7 phase structures, correspond to two deep eutectic compositions of Cu61.8Zr38.2 and Cu56Zr44. Cu64Zr36 is the best glass-forming composition in the Cu-Zr binary system. Three e/a-variant composition lines (Cu64Zr36)100-xNbx, (Cu61.8Zr38.2)100-xNbx and (Cu56Zr44)100-xNbx were constructed in the Cu--Zr--Nb system by linking these three specific compositions with the third constitute Nb. The pure Zr and Nb elements were first melted into interalloys, then the interalloys were melted with Cu, and finally alloy bars with diameter of 3 mm were prepared by copper mould suction casting. Minor Nb additions (atomic fraction, x≤3) can improve remarkably the glass forming abilities of the Cu-Zr alloys. The optimum composition Cu60.3Zr37.2Nb2.5 with the highest Tg/Tl =0.626 is located on the e/a -variant line linking the third element Nb and Cu8Zr5 icosahedral cluster and Cu61.8Zr38.2 which possess the deepest eutectic point. The glass formation relative to clusters in Cu-Zr system is also discussed.

Semiconductor transformation of PZT-5H ferroelectric ceramics induced by hydrogen has been investigated. The results showed that the leakage current and carrier concentration increased and the resistivity decreased with increasing hydrogen concentration, and the color of specimen changed from yellow to black. Hydrogen could induce a transition of the insulating PZT-5H ferroelectric ceramics to n-type semiconductor. During charging in H2 at the temperature higher than the Curie point, hydrogen would restrain the phase transformation from cubic to tetragonal, resulting in disappearance of ferroelectricity at room temperature. Charging at room temperature, however, did not change the crystal structure of the tetragonal ferroelectric ceramics. The properties and color of PZT-5H were reinstated after outgassing at high temperature.