The microstructure of a new wrought superalloy under standard heat treatment condition was studied by means of thermodynamic calculation, optical microscope, scanning electron microscopy, transmission electron microscopy and chemical phase analysis. The main mechanical properties were given for comprehensively understanding the tested alloy. The results indicate that the tested alloy under standard heat treatment condition is composed of equiaxed grains with different sizes. The spheric γ′(Ni3（Al，Ti）) is the main strengthening phase of the alloy and distribute dispersedly in the matrix whose size is very small.Cr23C6 and a few （Ti，Mo）C mainly precipitate on the grain boundaries and some of them precipitate in intracrystalline. Besides, There are very few M6C in the tested alloy. The tested alloy under standard heat treatment condition not only has higher strength but has better plasticity and ductility, has higher creep strength than that of Waspaloy alloy.

TiAl alloys are potential candidate materials in automotive and aerospace industries for high-temperature structural applications. However, the low room temperature plasticity limits their wide application. Rapid solidification technique may improve the properties through modification of microstructure. In this paper, the evolution and character of microstructure and mechanical properties of rapidly solidified TiAl alloys produced with various processing methods, and the effect of alloy additions on the solidification behavior, microstructure and properties were overviewed, including the production and stability of metastable phases, consolidation processes of rapidly solidified ribbons/powders. It is expected to provide useful information for future research and development of TiAl alloys with improved properties for future engineering applications.

Thin plate of ultra-high strength steel 300M was fabricated by the laser melting deposition manufacturing process. Microstructure of the steel was analyzed by OM and SEM. The Rockwell hardness (HRC) profile was measured along depositing direction. Results showed that the as-deposited 300M steel plate had a rapidly solidified cellular dendrite structure. Solid-state phase transformation microstructure of the 300M steel varied notably with the increasing deposition height, with a tempered martensite and bainite mixed structure in the bottom part, a mixture of carbide-free bainite and island-like matensite-austenite duplex structure in the middle-lower part and a mixed martensite-bainite structure in the middle-upper part. The hardness profile varied as stepwise with the increasing deposition height. The step-like hardness profile and the variable post-deposition transformation microstructures along the depositing direction were caused by the particular cyclic thermal behavior of the laser melting deposition manufacturing process.

The influence of Al2O3 on vanadium concentration in V-bearing steelmaking slag was stud ied. It was found that the prior precipitated phase of Ca2SiO4（S）contained V and P reacts with （Al2O3）to produce a new V- bearing mineral（Ca3(V,P)2O8•nCa2SiO4），and gehlenite（Ca2 Al2SiO7），when the melt slag modified by Al2O3 cooled down to1623K slowly.As the content of （Al2O3）increasing, Ca2SiO4 will vanished.Because（Al2O3）continue to react with Ca2SiO4 in the new V- bearing mineral,to produce gehlenite. the vanadium concertration in Ca3(V,P)2O8•nCa2SiO4 will increase.results also indicate that the phase of Ca3(V,P)2O8•nCa2SiO4 will be produce enormously and vanadium content in Ca3(V,P)2O8• nCa2SiO4 is high by method of control Al2O3 content in slag. This results provides a solid basic for the design of vanadium concentration mineral and increased the content of vanadium in the V-enriched mineral as much as possible.

In this paper we analyze the influence of rotating magnetic field driven forced convection on solidification microstructure, through investigating the solidification of Sn-Bi alloys in rotating magnetic field (RMF). We found that the RMF can eliminate macrosegregation，cause the fracture of dendrites and refinement of solidification structure, accelerate the velocity of melt and the diffuse of solute near the solid-liquid interface, decrease eutectic spacing, and cause the regional difference of eutectic microstructure. At the same time, there is a transition from dendrite-eqiaxed-orbed-dendrite growth with increasing the rotating frequency. The basic reasons of dendrite fracture and growth form transition and the eutectic spacing change consist in the enhancement of the melt velocity, the homogenization of temperature and solute fields, the relative motion between the primary phase and the melt caused by the electric conductivities difference. The reason of macrosegregation elimination is that the primary phase is affected by the combined effect of gravity, buoyancy and Lorentz force. Furthermore, the physical mechanism on the transition of solidification microstructure by rotating magnetic field is discussed.

The present studies are to investigate the microstructural features of proeutectoid ferrite during transformation from austenite to ferrite under different magnetic field strength on Fe-0.76%C alloy. It’s found that the amount of proeutectoid ferrite from austenite to ferrite phase transformatio increased considerably with the increase of magnetic field strength. The carbon content of eutectoid point increases considerably also as the increase of magnetic field strength. The most possible reason is that the magnetic field shifts the eutectoid point to high carbon and high temperatures sides and increases the starting-temperature of the phase transformation from austenite to ferrite. The preutectoid ferrite grains elongated along the magnetic field direction, and the angle between the major axis of proeutectoid ferrite and magnetic field direction was decreased with the increase of magnetic field strength. the most possible reason is that the preutectoid ferrite became the magnetic dipolar under high magnetic field, and then austenite atom around the preutectoid ferrite as magnetic dipolar was prone to diffusion to ferrite grain along the magnetic field direction.

It described a numerical simulation study for the multiphase phenomena of magnetic field, liquid steel flow field and inclusion behaviour, considering the coupled effects of electromagnetic brake (EMBr) and argon gas injection in the slab continuous casting mold with high casting speed. The effects of the EMBr and argon gas flow rate on the liquid steel flow and inclusion removal rate have been investigated. The results show that EMBr could slow down the flow velocity of liquid steel effectively, especially near the meniscus surface, but it had no helpful for the removal of small inclusions and the removal rate for the inclusion particles in diameter range of 5~50μm reduced from 6.7% without EMBr and argon gas injection to 3.3% with EMBr in the mold. The argon gas injection could increase the liquid steel flow up tendency of the upper circulating area and the floating up rate of inclusion particles with the size 5~50μm increased to 8.9%. The increasing of argon gas flow rate resulted in a stronger eddy zone near the free surface especially near the submerged entry nozzle (SEN) and formed the secondary vortex flow easily, which impacted the fluctuation of free surface and the slag entrapment. The double action of EMBr and argon gas injection could increase the floating up rate of inclusions and the removal rate of small inclusions with the size 5~50μm increased to 12.2% and the rate for inclusions to be trapped into solidified shell was reduced to 64.4%.

The formation of a double-recirculation flow pattern(DRFP) in continuous casting mold will be helpful for the improvement of slab quality. In the present study, the condition for the formation of the DRFP in a slab continuous casting mold with blowing argon gas was quantitively described using the Lagrange multi-phase flow model, and the prediction was validated by the water model. The influences of argon gas volume flowrate, fluid steel mass flowrate, mold width, submergence depth of SEN (Submerged Entry Nozzle) and port downward angle on the DRFP were numerically investigated. The results show that it is important for ensuring the DRFP that the argon gas flowrate matchs the other casting conditions. The critical argon gas flowrate increases with the increasing fluid steel mass flowrate, and the range of argon gas flowrate for keeping the DRFP will be enlarged by decreasing the mold width and increasing the submergence depth of SEN as the fluid steel mass flowrate is more than 2.486 ton/min, nevertheless, the port downward angle of SEN has little effect on it. However, the operation parameters have no significant influence on it as the fluid steel mass flowrate is below 2.486 ton/min.

By means of template effect α-W thin films were successfully coherent grown on pre-deposited Mo seed-layer on Si substrates at ambient temperature by magnetron sputtering. Microstructures have been studied by X-ray diffraction, field-emission scanning electron microscopy and high-resolution transmission electron microscopy techniques. Residual stress and electric resistance of thin films were investigated by wafer curvature method and standard four-probe technique. Observations show stable α-W in equiaxial-grain shape is preferred on Mo layer driven by template effect while metastable β-W with non-equiaxed grain structure appears to form on Si substrates. With increasing tungsten film thickness, resistivity and residual stress increase for above two series of samples. For the case of β-W, the thickness dependent properties indeed resulted from increasing grain boundary. Whereas, for α-W case, the constraint of coherent interface between α-W and Mo will dominate electric resistance and residual compressive stress, especially at film thicknesses equal to or smaller than tens of nanometers.

Vicker’s microhardness tester equipped with diamond pyramid indenter was used to carry out microhardness tests on 0Cr18Ni10Ti stainless steel welded joint. Indentaion size effects (ISE) of different regions at the joint, including the weld metal (WM), base metal (BM), fusion zone (FZ) and heat-affected zone (HAZ) were studied at loads varying from 10 to 500 g for a constant dwell time of 10 s. The results show that the microhardness for each region of the welded joint decreases with the increasing load at comparatively low loads, and then tends to invariable as the indentation load exceeds 200 g. The PSR model was adopted to accurately describe the variation of the hardness as a function of indentation test load. The error between the tested hardness at 200 g of applied load and the calculated value using this model is less than 3%. Indentation tests were also successively performed across the welded joint to evaluate the distribution of the microhardness for different regions of the welded joint and optical microstructures are observed and analyzed. The yield stress distribution of the welded joint was also calculated according to its relationship with the hardness.