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Microstructure of as-cast, quenched and tempered high sulfur steels was observed, and the sulfides in different heat treatment states were analyzed by professional image software Image Pro Plus. The results show that the matrix structure of high sulfur steel before heat treatment is mainly composed of lamellar pearlite and ferrite distributed along grain boundaries. The sulfide mainly distributes in the matrix in the form of flocculent, spherical, long strip and spindle. The distribution of sulfide in high sulfur steel before heat treatment is not uniform and the overall bearing capacity is not uniform. It has poor capability and wear resistance, and is not suitable for high speed and heavy load. Statistical analysis of sulfides in high sulfur steel before and after heat treatment by Image Pro Plus software shows that the average size of sulfides increases and the number decreases after quenching, while the average size decreases and the number increases after tempering. The matrix hardness of high sulfur steel after tempering is lower than that after quenching, but the hardness of sulfide after tempering do not change much; the hardness of high sulfur steel after quenching or tempering are get the maximum when quenching temperature is 840 °C. Keywords: High sulfur steel, Sulfide, Computer image, Microstructure, Statistics

In order to improve the material utilization ratio of automobile oil pump shaft, the extrusion wedge cross rolling process was developed to form automobile oil pump shaft, the results show that the volume of the blank head produced by extrusion cross wedge rolling is reduced by about 75% compared with that produced by traditional cross wedge rolling, and the material utilization ratio can be increased to about 95%. The microstructure distribution of automobile oil pump shaft formed by this process was studied systematically by fem simulation and experiment, get the forming process can make the grain size of oil pump shaft rolling parts refine continuously, and finally obtain fine and uniform grain structure. The average grain size measured by the experiment is in good agreement with the simulation results. The research results lay a theoretical foundation for reducing oil pump cost and improving life.

Steel 30CrMnSiNi2A slices were irradiated by a continuous wave fiber laser beam with the intensity of 14.5W/cm2. Alloy samples with various temperature processes were obtained by changing the laser irradiation time, irradiation times and atmosphere environment. X-ray diffraction, scanning electron microscope, energy dispersive spectrometer and nanoindentation system were employed to characterize their microstructure morphology and mechanical properties. Three layers were observed in the samples fracture, namely oxide film, hard brittle layer and alloy substrate. The hard brittle layer had a higher hardness and a lower toughness compared with the base metal. Referring to the temperature history, we deemed that the surface oxidation and the solid phase transformation were the main factors which changed laser coupling efficiency. The results also illuminated the correlation between the microstructure morphology and the response to laser irradiation of the samples.

Inequi-atomic Al0.4FeCrNiCo1.5Ti0.3 high entropy alloy has been fabricated by mechanical alloying (MA) and hot-pressing sintering (HP). The microstructure, the phase evolution and the mechanical properties of Al0.4FeCrNiCo1.5Ti0.3 alloy were investigated by XRD, SEM and an instron testing system. Results show that a simplex solid solution consisting of fcc and bcc phase is formed in 10 h ball-milling time during MA, while a fcc and two types of bcc phase (bcc1 and bcc2) are noticed after HP process. The sintered alloy exhibits excellent comprehensive mechanical properties with a high relative density of 99.48%. The yield strength, the compressive strength, the compression ratio and Vickers hardness (HV) of the alloy are 2.13, 2.54 GPa, 20.1% and 7250 MPa, respectively. The superior strength of inequi-atomic Al0.4FeCrNiCo1.5Ti0.3 high entropy alloy is attributed to solid solution strengthening, and the fracture mechanism exhibits a mixed mechanism consisting of intergranular fracture and plastic fracture modes.

In order to measure the three-dimensional microstructure of surface defects on optical component, a novel measuring method based on digital image-plane holographic microscopy (DIPHM) is proposed in this paper. The experimental system has been designed and built to measure the microstructure of optical component’s surface defects. The object light wavefront can be reconstructed by using the algorithm based on the angular spectrum theory, and the technique of phase correction is contributive to eliminate the system error. There is a definite relationship between the object light wavefront and the surface topography, so the 3D microstructure of surface defects can be measured. This measuring technique is helpful to judge the damage degree of the optical component and analysis the influence of the surface defects, and it is of great significance to ensure the laser system security running.

In this paper, the pretreatment of concentrates by extrusion machine was present to improve the granulation of blends comprising some 30% iron ore concentrates and enhance the sintering performance. It is shown that by pretreatment of fine concentrates through extrusion machine, the content of +3mm fractions of granulation mixture and sinter mixture permeability are elevated by 10% and 35%, respectively. In the meantime, an increase in sinter productivity from 1.51 to 1.62t.m-2.h-1 is attainted in pot tests with similar sinter tumble index and at lower coke rate. The mechanism of the pretreatment of concentrates process to improve sintering performance of fine iron ore concentrates was demonstrated by mineralogy that better permeability help form more calcium ferrite and good microstructure of sinter, further proven by the better metallurgical performance of sinter.

The microstructures and dielectric properties of Y/Zn codoped BaTiO3 ceramics sintered in a reducing atmosphere were investigated. XRD analysis indicated the crystal structure of samples change from tetragonal to pseudocubic with increasing Y2O3 and ZnO content. SEM micrographs showed Y2O3 can suppress grain growth more effectively compared with ZnO, which is ascribed to the presence of second phase Y2Ti2O7. Proper amount of Y2O3 and ZnO can significantly improve the dielectric temperature characteristics due to the formation of grain core-shell structure. The high performance dielectrics meeting the X7R code were achieved by codoping 1.5 mol% Y2O3 and 3.0 mol% ZnO.

BaTiO3-based ultrafine nonreducible dielectrics for multilayer ceramic capacitors were prepared by a newly developed nanocomposite doping process. According to TG-DTA, XRD and TEM analysis, the nanocomposite dopants via sol–gel method were uniform and well dispersive. The micromechanism was investigated based on comparing conventional process with nano-doping process. It indicated that due to the special nano-effect, doping effect of additives became more effective and the microstructure and dielectric properties of ceramics were improved. The results showed that high performance dielectrics satisfying X8R specification were achieved, with high dielectric constant of 2,900, low dielectric loss of 0.6% and large insulation resistivity of 1012 Ω cm.

The effect of sintering atmosphere on the microstructure and capacity-temperature characteristics (TCC) of Yb-Mg and Yb-Mn substituted BaTiO3 was investigated. The XRD and SEM results indicated the suppression of the solubilities of the acceptor ions when firing under reducing conditions. Mn was confirmed to promote the grain growth of Yb2Ti2O7 while Mg could suppress the grain growth of this second phase. The X8R specification (−55 to 150°C, ΔC/C=±15% or less) could be satisfied by firing under proper conditions for the two compositions. It is suggested that the change of the solubilities of the acceptor ions, as well as the valence states of the Mn ions would affect the TCC behavior of the core-shell-structured BaTiO3 materials.

This paper systematically studied the factors including Pb concentration of precursor, PT seeding layer and TiO 2 and ZrO 2 seeding layers, which influence greatly the crystal orientation of lead zirconate titanate (PZT, Zr/Ti=52/48) thin films fabricated by sol–gel process. We find that the PZT films deposited by precursor with 20% mole excess Pb displayed strong (1 1 1) preferred orientation, with 5% mole excess Pb showed a little (1 0 0) orientation and pyrochlore phase. PT seeding layer was found prompting the PZT films phase transformation with (1 1 0) preferred orientation. In addition, the results show that the TiO 2 and ZrO 2 seeding layers had totally different effects on the preferred orientation of PZT films. The films with TiO 2 seeding layer were highly (1 1 1) oriented and exhibited better ferroeletric properties (remnant polarization Pr=14.2 μC cm −2 , coercive field E c =59.1 kV cm −1 ) than those of the films with ZrO 2 seeding layer shown (1 0 0) orientation (Pr=7.4 μC cm −2 , E c =42.9 kV cm −1 ).

The microstructure and dielectric properties of Yb-Mn- and Yb-Ni-substituted BaTiO3 ceramics are investigated in this paper. Both Yb-Mn- and Yb-Ni-substituted BaTiO3 ceramics satisfy the X8R specification (−55 ∘C to 150 ∘C, Δ C = ±15% or less) for automotive application when CaZrO3 is incorporated in the formulations. It is found that both Mn and Ni ions can suppress the diffusion of Yb and CaZrO3 into BaTiO3 grains, resulting in formation of core-shell structures in the grains. It is found that Mn is more favorable to stabilize the core-shell structure in BaTiO3 ceramics as compared with Ni.

The effect of Yb/Mg co-doping on the microstructure and electrical properties of BaTiO 3 ceramics sintered under oxidizing, reducing and annealed conditions was investigated. XRD analyses indicated the suppression of the solubilities of the acceptor ions in BaTiO 3 under the reducing and annealed conditions . DSC measurements indicated that addition of too much Yb would cause the collapse of the core-shell structure in the BaTiO 3 ceramics. The effect of sintering atmospheres on the microstructure and dielectric properties was attributed to the change of the solubilities of the acceptor ions in this core-shell-structured material.

A new route was developed to produce high-performance nonreducible (Ba,Ca)(Ti,Zr)O3 (BCTZ) ceramics, in which sol-gel derived complex dopants were applied to ultrafine (Ba0.97Ca0.03)1.001(T{i}0.80Zr0.20)O3 powders. The effect of calcination temperature on the complex dopants, as well as the effect of complex dopants on the BCTZ ceramics was investigated. The micro-strain, Curie point, dielectric loss and maximum dielectric constant at the Curie point of the resulting BCTZ ceramics all decrease with increasing mean crystallite size as the calcination temperature of the complex dopants increases. It is suggested that the above results are presumably due to the downsizing of the agglomerates of the complex dopants during calcination. The effectiveness of the present route to improve the dielectric constant and loss of the BCTZ ceramics simultaneously has been verified in comparison to the conventional mixed oxide route. This new route is very promising for practical use in Ni-electrode multi-layer ceramic capacitors (Ni-MLCCs) with large capacitance.

With the use of SEM, EDS and X-ray diffraction, the microstructure and phase composition of Ni3Al intermetallic coating obtained by light beam surfacing were investigated. Moreover, the effect of heat input on the precipitation characteristic and order degree of Ni3Al was also analyzed. The results show that with the Ni and Al mixed powder of 3:1 atomic ratio as surfacing material, the light beam surfacing layer cannot entirely consist of Ni3Al owing to the oxidation burning loss of aluminum and the dilution of the molten pool by base metal. The surfacing layer with lower heat input (3000 J/mm) is composed of the eutectic of Ni3Al and γ-(Fe,Ni). The increase of heat input (4200 J/mm) leads to intensified dilution of molten pool and increased oxidation burning loss of aluminum, which results in the reduced aluminum content in molten pool. The microstructure of the surfacing layer with higher heat input is the hypoeutectic of Ni3Al and γ-(Fe,Ni), a lot of particle α-Fe precipitates within γ-(Fe,Ni) phases, and the order degree of Ni3Al increases. With the increase of heat input, the microstructure of transition zone between surfacing layer and base metal changes from γ-(Fe,Ni) to lath martensite with hardness of HV740.

The influence of Nb on the microstructure and dielectric properties, including temperature dependence of permittivity, dielectric loss, and Curie temperature, has been investigated on Ni-doped BaTiO3 ceramics. Experiments reveal that incorporation of a proper content of Nb in Ni-doped BaTiO3 can control the grain growth, reduce the dielectric loss, shift the Curie temperature to higher temperatures and significantly improve temperature characteristics of the BaTiO3 ceramics. As a result, a novel X8R material is developed in the system, which is very promising for practical use in X8R multi-layer ceramic capacitors (MLCCs).