High pressure gas atomization experiments have been carried out with Al-Pb immiscible alloy. Powders containing fine Pb dispersions have been obtained. A model describing the microstructure evolution in a rapidly solidified atomized droplet was developed. The model takes into account of the common effects of the nucleation, the diffusional growth of the minority phase droplets, the collisions and coagulations between the minority phase droplets and spatial phase separation. The formation of the microstructure of the atomized droplets was calculated. It was demonstrated that the calculated results have a good coincidence with the experimental ones. The solidification process of the atomized Al-Pb alloy drop was discussed in details.

Electron structure of ZrMn2 alloy and its hydride are calculated by plane wave pseudo-potential method which is based on density functional .It is found that chemical bond between Mn(2) and Mn(2) atom is stronger than that between Mn(2) and Zr atom in ZrMn2 alloy. After hydrogenation, the interaction between Mn(2) atoms decreases evidently in strength, which is one of the reasons why the alloy is powdered after absorbing and desorbing hydrogen constantly. There is a weak interaction between H and Zr atom along c axis, and lattice expansion makes Zr atom shift easier outward while hydrogen enters absorbing tetrahedron in ZrMn2 alloy, as result, the expansion along c axis is larger than that along a axis in ZrMn2H3 hydride.

Grain boundary character distributions×(GBCD) in Pb alloy after varying kinds of thermomechanical treatments were analyzed by electron back scatter diffraction (EBSD) and orientation imaging microscopy (OIM). The frequencies of lowΣcoincidence site lattice(CSL) grain boundaries in Pb-alloy can be enhanced to more than 70% after proper cold rolling combined with annealing which was carried out at high temperature（0.9 Tm ）for a very shot period of time. Together withΣ1 boundaries, the Σ3 boundaries appeared during recovering. The development of Σ3 boundaries in the process of recovery and recrystallization is the main reason for enhancing the frequencies of lowΣCSL grain boundaries. Triple junctions which contained three CSL grain boundaries could be easily find in the OIM of the specimen that had high frequencies of lowΣCSL grain boundaries, and there are specific orientation relationships among the grains assembled by the triple junctions

Crystal zirconium bar and sponge zirconium were employed as raw materials to prepare wedge-like specimens of Zr52.5Cu17.9Ni14.6Al10Ti5 bulk amorphous alloy with different oxygen impurity contents by a tilt casting method using ladle hearth type arc furnace. Oxygen impurity effect on the alloy’s glass forming ability and thermal stability was investigated. It is shown that the glass forming ability of the quinary alloy characterized by maximum amorphous sample forming thickness tmax decreased as oxygen impurity content increased, on the contrary, its thermal stability characterized by supercooled liquid region ΔTX enhanced. The reason that oxygen impurity made Zr52.5Cu17.9Ni14.6Al10Ti5 alloy’s thermal stability increased related to its higher reduced glass transition temperature Trg.

The effect of hydrogen charging on the microstructure (α+β)/βtransformation and the mechanical properties of Ti-60 alloy at high temperature have been investigated. The results show that the volume fraction of primaryαand the (α+β)/βtransformation temperature is continuously decreased with increasing hydrogen contents. The result also indicate that the yield strength at high temperature is also continuously decreased with hydrogen concentration, and the minimum yield strength occurs at a concentration which corresponds to the (α+β)/βtransition and that further increase in yield strength is due to the hardening effect of hydrogen addition in the βphase.

An investigation into the microstructure in directional solidified hypoeutectic Al-4.5Cuwt.％alloys under a longitudinal magnetic field shows that the field has a great influence on the dendritic arrays. The field causes severe distortion in the dendritic array morphology in the mushy zone and disappeared below the eutectic isotherm at lower growth speed R=5µm/s, as opposed to the well-aligned dendritic crystals in the absence of the field; At the growth speed R=50µm/s and a temperature gradient in the liquid of 38K/cm, the alignment structure forms and the crystal direction <111> turns to the direction of the magnetic field, as opposed to the dendrite growth along the crystal direction<100>. It has also been found the field causes the increase of primary dendrite arm spacing at the growth speed R=100µm/s, Above phenomena is analysed on the base of the TEMHD theory and crystal.magnetic anisotropy theory.

The effects of atomic hydrogen and flaking on mechanical properties of a wheel steel have been investigated. The results show the critical diffusible hydrogen concentration for forming flaking is C*0=1.3×10-6（or total hydrogen concentration C*T=3.7×10-6）. If the amount of the flacking exceeds a critical value,e.g., C0≥5.6×10-6, it causes the plasticity and strength to decrease sharply. For a wheel, the amount of flaking is below the critical value because of C0<3.9×10-6,thus there is no effect of flaking on tensile properties and fracture toughness KIC. Atomic hydrogen doesn’t influence fracture toughness, but causes plasticity to decrease evidently during slow strain rate tension. Atomic hydrogen can also causes hydrogen –induced delayed cracking under constant deflection loading and the threshold stress intensity factor of hydrogen –induced delayed cracking, KIH, decreases linearly with increasing diffusible hydrogen concentration i.e., KIH＝57.8-3.9 C0. However there is no effect of the flaking on hydrogen-induced delayed cracking

The grain growth behavior in reactive spray formed TiCP/7075 Al alloy was studied and compared with that of spray formed 7075 Al alloy at semi-solid state. The specimens were heat-treated isothermally at 600℃ for times in the range of 10-60min,then quenched in water. The microstructure of reheated specimens was characterized using OP、SEM and TEM. The grain size was measured using a mean linear intercept method. Results shows that the in-situ TiC particles can effectively retard grain growth, grain growth exponent (n) for Arrhenius equation was increased from 2 to 3, which indicates that the in-situ TiC particles have the significant pinning effect on grain coarsening in the semi-solid state. The analysis also showed that the activation energy for grain growth for the samples with TiC addition was over twice of that for the samples without TiC additions, which made it more difficult for grain.

The rheological behavior of the semi-solid slurry of A356 aluminum alloy has been studied through a Couette-type viscometer. The experimental results show that the apparent viscosity of semi-solid A356 alloy increases with the fraction solid increasing, but decreases with the shearing rate increasing in the steady-state. When the solid fraction reaches a critical value, the apparent viscosities increase rapidly. An empirical equation that shows the effect of fraction solid and shearing rate on the apparent viscosity of semi-solid A356 alloy is built as the following, =13.61exp(6.09 ) -1.01.

Abstract In this paper, the recrystallization of the surface deformed structure of DZ4 directionally solidified superalloy was studied by SEM and X-ray diffraction. The results show that under the condition of two-hour holding, recrystallization takes place at 1000℃.The recrystallization layer increases slowly with the temperature rise when the heat treatment is performed at the temperature lower than that of the -solutioning, whose structure is cellular one, but increases rapidly when performed at the temperature higher than that of the -solutioning and the larger phase within the recrystallization layer decreases until totally disappeared. The recrystallization formed at temperature of 950℃ and 870℃ for long holding time is cellular structure. The rate and thickness of recrystallization mainly depend on temperature, which have little relation to holding time.

Superhard nanocomposite Ti-Si-C-N coatings were deposited on substrate of high speed steel using an industrial pulsed d.c. plasma chemical vapor deposition set-up. Dependence of Si and C contents and annealing at elevated temperatures on the microstructure and hardness of Ti-Si-C-N coatings were investigated. Detailed microstructure examined by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) suggested that the Ti-Si-C-N coatings was a nanocomposite structure composed of nanocrystalline Ti(C,N) and amorphous carbon and Si3N4. And the crystalline size and microhardness of coatings showed high thermal stability even at 1000° C when Si and C contents were higher of 12.1 at.% Si, 32.9 at.% C. The possible origin of high thermal stability of superhard nanocomposite Ti-Si-C-N coatings is explained by spinodal decomposition that occurs during deposition.

The ribbons with different thickness of Fe83Ga17 alloy were prepared by the melt-spun and the microstrcucture and magntostriction were investigated. It was found that the magnetostriction was related to the thickness of ribbons and the maximum magnetostriction of -2100 ×10-6 has been obtained in the ribbon with thickness of 75 μm. The XRD and DSC results showed that DO3 structure emerges in those ribbons with thickness of 45、55、75μm. The transition of A2＋DO3→A2 occurred at 669℃ for the ribbon of 75 μm. The microstructure of ribbons showed that the increase of melt-spun cooling rate can restrain the precipitation of Ga-rich phase. It is considered that the giat magnetostriction of ribbons originates from the A2 +special DO3 structure and shape magnetic anisotropy .

A wear resistant metal silicide alloy consisting of Cr13Ni5Si2 ternary metal silicide dendrites and the interdendritic nickel-base solid solution (γ) was designed and fabricated by the laser melting/continuous deposition process. Wear resistance of the Cr13Ni5Si2/γ alloy was evaluated on an MM-200 block-on-wheel dry sliding wear tester at room temperature. Results indicate that the Cr13Ni5Si2/γ alloy has excellent wear resistance and extremely low load-sensitivity of wear under dry sliding wear test conditions.

Near-threshold fatigue crack propagation tests were conducted under combined torsion and tension on a circumferentially pre-cracked round bar of an austenite steel. The propagation behavior was studied extensively under various combinations of cyclic loads. The threshold condition of fatigue crack extension was expressed by a quarter-elliptic function in terms of the stress intensity factor ranges for mode I and III. The equation can be derived on the basis of the crack-tip displacement criterion. The threshold condition for fracture is also expressed by another quarter-elliptic function.

Uni-axial tensile deformation of LA41 magnesium alloy has been carried out and PLC phenomenon, also known as serrated flow or plastic instability, is observed. This kind of alloy exhibits negative strain rate sensitivity (SRS) at room temperature, that is, SRS is negative throughout the strain rate range from 3.33×10-4 s-1 to 6.66×10-3 s-1 at ambient temperature. Both ultimate stress and 0.2% proof stress decrease with increasing strain rate, whilst critical strain of serrated flow is found to rise with enhanced strain rate. A new explanation for this unusual phenomenon is presented. The model of dynamic strain aging (DSA) is established though thorough discussion.

The laws of entropy conservation and energy conservation are applicable to any system. In this paper, a new energy model for low cycle fatigue (LCF) life prediction has been derived from the above two laws. Based on this model, an investigation of cumulative damage was also accomplished. By low cycle fatigue experiment of 316L steel under stress control at 420℃, the prediction of fatigue life and residual life has been carried out by the new energy model and the principle of linear accumulation damage based on this model. The predicted results have been compared with the experimental data. A good agreement is noted between the predicted and experimental results.

The wettabilities of In-Sn alloy melts on the amorphous and crystalline Cu46Zr45Al7Gd2 substrates were studied by the sessile-drop method, and the interfacial characteristics of In-Sn/Cu46Zr45Al7Gd2 were investigated by scanning electron microscopy（SEM），electron probe microanalysis (EPMA) and X-ray diffraction(XRD). The results show that the wettability of In-Sn alloy melts on amorphous substrate is superior to that of In-Sn alloy melts on the crystalline one; the width of diffusion layer of In-Sn alloy melts on the amorphous substrate is thinner than that of In-Sn alloy on the crystalline one under identical conditions. The crystallizations occur in the diffusion zone during the wetting process of In-Sn alloy melts on amorphous substrate.

Intermetallic compounds (IMC) near the interfaces of solder joints has significant effects on joint reliability. In this paper, 150 oC aging and high temperature reflow of Sn-3.5Ag-0.7Cu solder joints on Ni-P/Cu were performed. For two aging processes, the IMC growth, morphologies, compositions and their effect on joint reliability were studied. The results indicate that the IMC morphologies and compositions in condition of 150 oC aging were much different from that in condition of reflow. Long time 150 oC aging results in large clusters of Ag3Sn IMC in solder. Brittle Ni3P layer was found after high temperature reflow, which was absent in long time 150 oC aging.. Under both conditions, ternary Ni-Cu-Sn IMCs were observed between solder interfaces. The morphologies, compositions and thickness of IMC affected the strength of solder joints.

Based on the control-volume method a 3-D comprehensively coupled model has been developed for binary iron-carbon to describe the turbulent fluid flow, heat transfer, solidification, and solute redistribution in the thin slab continuous casting process. The calculated results show that the turbulent fluid flow dramatically alters the shape of the isotherms and the distribution of the solute in the thin slab. The thickness of solidified shell is uneven along broad face because of the flow jet. The formation mechanism of macrosegregation is investigated and the possible position of the macrosegregation is analyzed.

The hot deformation behavior of GH2674 has been studied in the temperature range 950-1200℃ and strain rate range 0.001-10 s-1, using hot compressing testing on a Gleeble-1500 simulator. A processing map is developed on the basis of these data and using the principles of dynamic material modeling. The map exhibits two domains: one at 1050℃ and 0.01 s-1, with a peak efficiency of power dissipation of 38%, the second at 1150℃ and 10s-1, with a peak efficiency of 40%. On the basis of optical microscopic observations, these they are interpreted to represent two dynamic recrystallization(DRX) domains, of which the mechanisms are different. The map also exhibits a long concave band in the temperature range 1075-1100℃，which may be related to the solutionizing of M3B2 phase. At temperatures lower than 1000℃ and strain rates higher than 0.1s-1, the material may be subjected to potential instabilities, while at temperatures higher than 1050℃ and strain rates lower than 0.01s-1 , the material exhibits significant grain coarsening, furthermore, the wedge cracking would appear at 1200℃ and 0.001s-1. On the basis of the constitutive behavior of GH2674 alloy as revealed in the processing map, the hot working schedules have been designed primarily