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This work aims to evaluate the use of miniaturized tensile specimen (MTS) to characterise the mechanical properties of alloys developed through rapid alloy prototyping (RAP), where high throughput tests are required on relatively small amounts of material. Tensile tests were conducted at a variety of strain rates and with increasingly smaller specimen sizes, ranging from larger specimens conforming to ASTM/ISO standards, down to small non-standard specimens. The gauge lengths of the specimens ranged from 50 to 80 mm for the standard specimens down to 5–10 mm for the non-standard specimens. To generalize the non-standard MTS designs, three alloys, DP800, DP600 and 316L stainless steel, were adopted. The results obtained from non-standard designs were compared with those from standard designs. The results show that non-standard designs can give repeatable results for yield strength (YS), ultimate tensile strength (UTS) and uniform elongation (eU). The maximum result differences of YS, UTS and eU are 7.37%, 7.71% and 11.9%, respectively, for DP alloys comparing standard and non-standard dimensions. These values are 13.56%, 14.03% and 19.5%, respectively 316L steel. The total elongation (ef) increases as the specimen dimension decreases. The geometrically dependent constants (n) are 0.2, 0.31 and 0.11 for DP800, DP600 and 316L, respectively. However, the Young's modulus is hard to determine precisely from the miniaturized designs. The conclusion from this work is that miniaturized tensile testing can be used with confidence as a high throughput means of predicting standard mechanical properties across a range of steels.

The general flow characteristics of the molten steel and the behavior of molten steel and liquid slag interface (level fluctuation) in the mold with a new type of electromagnetic brake, freestanding adjustable combination electromagnetic brake (FAC-EMBr), was investigated by numerical simulation. The influences of the magnetic induction intensity, the submerged entry nozzle (SEN) immersion depth, the SEN port angle, and casting speed on the effect of FAC-EMBr are investigated. The results show that electromagnetic field formed by FAC-EMBr can cover the jet flow impact region, the upward backflow region, and the meniscus region simultaneously. With the increase of magnetic flux density, the jet flow impact intensity and the molten steel velocity in the upward and downward backflow regions are effectively suppressed, the meniscus wave height also decreases gradually, and the level fluctuation tends to be stable. For the influence of SEN port angle and SEN depth on the effect of FAC-EMBr mold, the results show that the molten steel velocity in the three main influence regions are all effectively depressed with increase of the value of SEN port angle and SEN depth. Even though under the condition of high casting speed (VC = 2.2 m/min), the application of FAC-EMBr can achieve effective braking effect.

This research aims to investigate the control effect of asymmetric flow in a slab mold using a novel magnetic field arrangement: freestanding adjustable combination electromagnetic brake (FAC-EMBr). Three scenarios (submerged entry nozzle moves to the narrow face, wide face of the slab mold, and rotates 10°) were studied using three-dimensional numerical simulation. The results show that the magnetic field generated by the FAC-EMBr system can effectively cover three key zones in mold and that the magnetic flux density in the zone cover by a vertical magnetic pole can be adjusted according to the actual flow condition. The FAC-EMBr can effectively improve the asymmetric flow in a mold and near the narrow surface caused by the asymmetric arrangement of the nozzle and can effectively inhibit the occurrence of the flow deviation phenomenon and stabilize the steel/slag interface fluctuation. At the same time, FAC-EMBr has obvious inhibition effects on the surface velocity and can optimize the asymmetric distribution of the surface velocity and the upper reflux velocity caused by the asymmetric arrangement of the nozzle. This study can provide theoretical evidence for the development and utilization of a new electromagnetic brake technology.

This research aimed at proposing a new type of magnetic field arrangement to suppress the meniscus fluctuation in slab continuous casting. The work was conducted by three dimensional (3D) numerical simulation and followed by an experiment validation. The results indicated that the maximum height of meniscus was decreased and the meniscus fluctuation was decreased significantly whilst the applied magnetic field was increased from 0 to 0.05 T. The surface velocity was not sensitive to the applied magnetic field magnitude to 0.05 T. The results obtained from the designed experiment had a good agreement with the simulation results: this is an indication of the effectiveness of the proposed magnetic field arrangement.

The brake effect of the freestanding adjustable combination electromagnetic brake (FAC-EMBr) and EMBr ruler on the behavior of molten steel flow and the level fluctuation were investigated with the numerical method. The effects of the horizontal magnetic pole position (EMBr ruler), magnetic induction intensity, and casting speed on two types of electromagnetic brakes were studied. The numerical simulation results show that the magnetic field caused by the EMBr ruler is mainly distributed under the submerged entry nozzle (SEN), and it is very weak nearby the meniscus area. After the FAC-EMBr is applied, the magnetic field is mainly distributed in the area below the submerged entry nozzle, the upper roll region, and in the meniscus region. The application of the electromagnetic brake can effectively suppress the impact of the jet and decrease the molten steel velocity in the meniscus area. The brake effect of the EMBr ruler on the behavior of the molten steel flow and the level fluctuation is significantly influenced by the horizontal magnetic pole position. The increasing of the magnetic flux density can significantly increase the velocity of molten steel in the upper roll region and lead to an intense fluctuation in the steel/slag interface, as the horizontal magnetic field cannot cover the three key regions. The brake effect of the FAC-EMBr is less influenced by the variation of the process parameters due to the addition of vertical magnetic poles. Additionally, the &ldquo, secondary braking effect&rdquo, of the vertical magnetic poles can help to lower the increase of velocity in the upper roll region caused by the excessive magnetic induction intensity and the high casting speed. Therefore, even under the high casting speed conditions, the application of a new type of FAC-EMBr is also an efficient way to suppress the molten steel flow and level fluctuation at the meniscus area and decrease the possibility of slag entrapment.

Bar-like sand mould tilted angle reduced free surface fluctuations. The primary and secondary reflected wave heights decreased with the scaling of Re0.8 and Re0.55, respectively. These heights were reduced by 54% and 51% when θ was increased from 0° to 5°. A larger tilted angle was found to generate an air cavity in the cast, the size of which was observed to vary with Reynolds number (Re). An optimised range of tilted angle (2°–3°) was proposed as a compromise to reduce the free surface fluctuations and maintain a perfect casting shape at the end of the filling stage.

Long-term external sulfate attack can result in significant concrete degradation. The purpose of this study is to develop an experimentally validated reactive transport model to investigate the transport behaviour of sulfate ions in concrete containing interfacial transition zone (ITZ). The model takes into account the spatially dependent pore size in ITZ and the change of diffusion coefficient of sulfate ions due to the formation of ettringite and gypsum in concrete pores resulting from the chemical reaction between sulfate ions and concrete components. The developed model was firstly validated by performing a series of experiments involving concrete specimens and sodium sulfate solution. Then, a series of parametric studies were carried out to identify the critical parameters that govern the transport of sulfate ions in concrete. The backscattered electron microscopy (BSE) results show that the porosity of concrete within ITZ is relatively higher than that in bulk paste with a six-fold higher porosity in inner ITZ (5 µm from aggregate surface) than that in outer ITZ (50 µm from aggregate surface). The model predictions suggested that the concentration of sulfate ions initially increases rapidly in concrete during the first 20 days and then the rate of increase gradually decreases due to the reduction in the diffusion coefficient of ions as a result of the ettringite and gypsum formation in concrete pores. In addition, it demonstrates that self-induced electric field has little influence in the transport of sulfate ions.

The steel/slag interface behavior under a new type of electromagnetic brake (EMBr), vertical electromagnetic brake (V-EMBr), was investigated. The influence of the magnetic induction intensity, the submerged entry nozzle (SEN) immersion depth, and the port angle of the SEN are investigated numerically. The effect of magnetic induction intensity on the meniscus fluctuation of molten alloy is further studied by the experiments. The results show that the meniscus fluctuation is depressed as the magnetic induction intensity is increased, especially for the region in the vicinity of the narrow face of the slab mold. This result is validated by the following experiments. For the influence of the SEN immersion depth and the port angle, the results show that the meniscus fluctuation is suppressed as the values of the immersion depth and the port angle are increased (absolute values for the port angle). However, the influence of the immersion depth and the port angle are not as sensitive as those in the other type of EMBr, e.g., EMBr Ruler. The industrial application of V-EMBr could benefit from this result.

We experimentally investigate the influence of the electromagnetic stirring (EMS) on the microstructure and the mechanical properties of Incoloy825 superalloy. Three trails of experiments with different values of the EMS alternating current (I = 0, 150 and 300 A, respectively), however with identical EMS frequency (f = 5 Hz), were conducted. We figure out that the equiaxed grain region is increased and the average grain size is decreased whilst EMS is applied. The application of EMS can also decrease the total number of TiN, especially for the inclusion in large scales (>2 μm). The values of the yield strength, the ultimate tensile strength and the elongation of Incoloy825 superalloy specimens are also increased whilst EMS is applied.

This research aimed at reveal the reasons for the extra Co–Cr–W alloy wastage in the risers in sand casting. The alloy filling behaviour in both the original and modified moulds was investigated numerically. The alloy–air interface was captured by using volume of fraction method. For the original mould, an unfilled volume in the vicinity of the runner bar top was apparent and it was refilled by a back flow, originated from the risers in the late stage of filling. The back flow behaviour required a higher level of the liquid alloy in the risers, which resulted in excessive wastage, and it was essential to form the required shape of the cast. For the modified mould, the unfilled volume was eliminated and the cast part shaping time was reduced to around 10 s from 90 s. The alloy wastage in the risers was reduced by 11%.

In this work, we synthesized a sun-like light source with tri-chromatic broad spectra, composed of light source units with single-peak 435-nm carbon quantum dots (QDs) and 695-nm perovskite QDs, and dual-peak 510- and 590-nm Ag-doped InP QDs, referencing CIE standard illuminants D50 and D65. Based on a spectral angle measure approach, we adopt the spectral similarity index (SSI) to measure the similarity between the synthesized light source and reference light source. We quantify the colour rendering and SSI of the tri-chromatic light source units and obtain the colour rendering and SSI as a function of chromaticity coordinate. The synthesized light source reaches an ideal performance with a maximum spectral similarity of 0.98 and colour rendering of about 93. This work is the first to synthesize a full-spectrum sun-like source with three QD light units, including a dual-peak QD unit, and proves QD LEDs as promising light sources for synthesizing full-spectrum light sources. In the future, improving the long wavelength part (>700 nm) of the broad-spectrum QD LED unit may significantly improve the colour rendering property.

An electromagnetic continuous casting mould designed is proposed with a non-uniform slit distribution structure. This design has aimed to reduce the number of slits so that the mould's strength is enhanced, whilst maintaining a similar metallurgy effect. In this paper, the metallurgy effect for the designed mould is investigated through the magnetic field distribution along the casting direction, the uniformity feature in the vicinity of the meniscus region, the temperature variation of the molten alloy pool and the mould wall. The results show that the designed mould achieved a similar effect as compared to the original mould; however, the configuration is simplified. This research highlights the topic of mould structure optimization, which would enable the Electromagnetic continuous casting (EMCC) technique to be utilized with greater ease by industry.

We investigate the influence of the specimen velocity on the magnetic flux leakage with the aim of selecting the optimum sensor locations. Parametric numerical simulations where the specimen velocity was in the range [0.1–20] m/s were carried out. As the specimen velocity is increased, the magnetic field varies from being symmetrical to being asymmetric. For the radial magnetic induction $$B_z$$ , the position at which the maximum difference between the minimum and maximum signal moves from the centre of the bridge towards the direction of the specimen movement. For the axial magnetic induction $$B_y$$ , the specimen velocity influence is dependent on the sensor location and a signal-velocity independent region was discussed.

For optical crossconnect and packet switched applications based on fast wavelength switching of distributed Bragg reflector (DBR) lasers, the wavelength switching delay is an important device characteristic. A large-signal model for a three-section DBR laser is described which permits evaluation of the intramodal and intermodal wavelength switching delay. The steady-state mode spectrum and loss obtained from a transmission line model of the laser are used in modified multimode rate equations to explicitly include the device structure and operating conditions in the dynamic model. Mode competition is shown to cause the intermodal wavelength switching delay to increase significantly as the destination wavelength approaches the edge of a mode tuning curve. The same behaviour is observed experimentally. >

Numerical calculations of the frequency modulation responses of monolithically integrated external-cavity semiconductor lasers are performed using G.P. Agrawal's (J. Appl. Phys., vol.56, p.3110-15, 1984) two-section model. Theoretical results show good agreement with the reported experimental results. The comparison of the modulation responses of the solitary semiconductor laser diodes, the conventional external-cavity semiconductor lasers, and the integrated passive external-cavity semiconductor lasers demonstrates that the integrated external-cavity semiconductor laser is the best choice for use in direct frequency modulation. >

We experimentally investigate the influence of an alternating electromagnetic field on the surface and internal qualities of Incoloy800H superalloy billets. The electromagnetic continuous casting experiments for Incoloy800H superalloy were successfully conducted and the billets (0.1 m × 0.1 m × 1.2 m) were obtained. We figure out that the high frequency (20.4 kHz) electromagnetic field which is applied in the mould region can improve the surface quality of Incoloy800H superalloy billet remarkably; the depth of oscillation mark decreases from 1.2 mm (without electromagnetic field) to 0.3 mm (with electromagnetic field). The internal quality of the billet was studied using a variety of characterization techniques. The low frequency (5 Hz) electromagnetic field which is applied in the second cooling region can improve the internal quality; the region of the equiaxed grain increases from 2.45% (without electromagnetic field) to 41.45% (with electromagnetic field). Furthermore, macro- and micro-segregation are suppressed and the TiN inclusion number is decreased as well.