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A new type wear block made of medium carbon low alloy steel was designed to improve the service of a centrifugal crusher. A reasonable casting technology was chosen and ViewCast software was used t...

The solidification process of a high chromium cast iron grate bar used for sinter machine was simulated, and high temperature oxidation resistance was also investigated. The simulation result shows that sequence solidification can be achieved and no shrinkage cavity and porosity were observed. Based on the analysis of the microstructure, it could be known that the grate bar was well protected by the Fe3O4、Fe2O3 and Cr2O3 oxide films at temperatures lower than 800°C.

A Ni 3 Al-Mo intermetallic compound alloy (IC6) was prepared by the multifunctional spray atomization and deposition plant. Tensile properties tests indicate that the spray deposited Ni 3 Al-Mo alloy possesses “ R ” characteristics in the yield strength, that is, the yield strength of the spray deposited IC6 increases with increasing of temperature and it reaches maximum at 760 °C. After that, it decreases with increasing of temperature. Analyses of dislocation structure by TEM reveal the relationship between the microstructure and yield strength. The results show that the change of the yield strength of the alloy with temperature is associated with the condition of dislocation winding, the pattern and quantity of the dislocation pairs and starting degree of the hexahedron slip system inside γ′ and γ phases. The TEM analysis of cracking by stereographic projection shows that with the increase of deformation stress the cracks form at grain boundaries and then quickly propagate, and some different slip bands exist in little planar zones; no matter at room temperature, middle temperature or high temperature, cracks craze along (111) plane octahedron slip.

Solute diffusion controlled solidification model was used to simulate the initial stage cellular to dendrite transition of Ti44Al alloys during directional solidification at different velocities. The simulation results show that during this process, a mixed structure composed of cells and dendrites was observed, where secondary dendrites are absent at facing surface with parallel closely spaced dendrites, which agrees with the previous experimental observation. The dendrite spacings are larger than cellular spacings at a given rate, and the columnar grain spacing sharply increases to a maximum as solidification advance to coexistence zone, In addition, simulation also revealed that decreasing the numbers of the seed causes the trend of unstable dendrite transition to increase. Finally, the main influence factors affecting cell/dendrite transition were analyzed, which could be the change of growth rates resulting in slight fluctuations of liquid composition occurred at growth front. The simulation results are in reasonable agreement with the results of previous theoretical models and experimental observation at low cooling rates.

In the work reported in this paper, rapidly solidified thin ribbons with compositions of Al(4–10 wt.%)Cr4wt.%RE (RE denotes La-rich misch metal) were produced by a single-roller technique. Phase formation and microstructures of the alloys were studied by X-ray diffraction, transmission electron microscopy, electron probe and energy spectrum analysis. Microhardnesses of the alloys were measured with a microhardness meter. The results show that the alloy Al(4–6 wt.%)Cr4wt.%RE is a promising materials for elevated temperture uses.

The microstructural evolution of Ti-45at.%Al alloy during directional solidification was simulated by applying a solute diffusion controlled solidification model，and the results have showed that under high thermal gradient the stable primary spacing can be adjusted by branching or competitive growth，irrelevant of the initial seed spacing. In addition，under a given pulling speed，increasing thermal gradient decreases primary cell/dendrite spacing，and under a given thermal gradient，increasing pulling velocity，we have observed a cell/dendrite transition region consisting of cells and dendrites，and which varies with the thermal gradient in a contradicting way，i.e. increasing the thermal gradient leading to the decrease of the range of the transition region. The simulated results agree reasonably well with experiment results.

Solute diffusion controlled solidification model was employed to simulate the columnar to equiaxial transition (CET) of TiAl alloy casting. The simulation results show that solute shock wave occurs when the diffusion fields of columnar and equiaxial dendrites meet. It could be one of the main factors blocking the columnar dendrite growth. Using this model, the CET in small castings was qualitatively predicted. It was found that the thermal gradient and solute undercooling ahead of the columnar tips of CET act jointly on CET, being in good agreement with experimental observations.