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The development of large infrastructure projects requires the consideration of many different risks in advance, of which the two common risks are strategic risk and project risk. This study provides an overview of the different relevant literature on risk management of large infrastructure projects. Based on the Hong Kong section of the Guangzhou-Shenzhen-Hong Kong high-speed rail, this study identified the project’s main strategic risks and project risks, and provided suggestions for risk management.

Under the background of global warming, the thermal comfort in summer in historical conservation areas in China has also been significantly negatively affected. How to optimize the spatial pattern of the street space of historical conservation areas to improve the thermal comfort in summer in these areas undoubtedly deserves the consideration of scholars. In this study, Taiping Street, a historical conservation area in Changsha, China was taken as an example. Combined with the actual conditions of Taiping Street, the models with different street interface densities, different sizes and positions of open space, and different D/H (the ratio between the width of a street and the height of its surrounding buildings) were built through ENVI-met. The measured meteorological data from 10:00 to 20:00 on July 12, 2022 in Changsha are used as the initial meteorological data for simulation. The effects of the difference in the above factors on the thermal comfort of street space of historical conservation areas were explored through simulation analysis and comparison of the thermal comfort in different models. In the study, it was found that the thermal comfort of street space in such a historical street space with narrow roads was significantly affected by architectural shadows. As a result, among the simulated models, the higher the street interface density in the street in the east-west direction is, the better the overall thermal comfort of the area is. The lower the street interface density of the street in the north-south direction is, the better the overall thermal comfort of the area is. by adding a small open space in the middle of the north-side of the building, the thermal comfort of the area can be improved. The higher the D/H ratio is, the better the thermal comfort of the model is. During the renewal of historical conservation areas, people should make full use of the architectural shadows in such historical blocks to improve the thermal comfort of the area. Besides, the commonly-used method of constructing ventilation corridors to improve the thermal comfort of the block did not have an obvious effect in this study and might not make obvious improvements in similar street spaces of historical conservation areas.

Lead-free (K0.5Na0.5NbO3)0.97–(Bi1.07FeO3)0.03 (KNN–BFO) ferroelectric thin films were epitaxially grown on LaNiO3-buffered SrTiO3(STO) by the pulsed laser deposition. The influence of the BiFeO3 addition on the electrical, bandgap, and photoelectric properties in KNN thin films was investigated systematically. Interestingly, compared with KNN films, the KNN–BFO thin films exhibit a significant enhancement on the ferroelectric and photoelectric properties. The enhanced ferroelectric properties were due to the depression of the leakage current and the improvement of the ferroelectric domains. Moreover, the photoelectric effect in the visible region can be ascribed to the improved ferroelectric properties and the narrow bandgap of KNN film modified by BiFeO3 addition. Our results indicate that the lead-free KNN–BFO thin films with enhanced ferroelectric and photoelectric characterizers may own a potential for environmental-friendly informational storage and photoelectric devices.

Diamond/Cu composites are widely studied as a new generation of thermal management materials in the field of electronic packaging and heat sink materials. The surface modification of diamond can improve interfacial bonding between the diamond and Cu matrix. The Ti-coated diamond/Cu composites are prepared via an independently developed liquid-solid separation (LSS) technology. It is worth noting that there are obvious differences for the surface roughness between the diamond-{100} and -{111} face by AFM analysis, which may be related to the surface energy of different facets. In this work, the formation of titanium carbide (TiC) phase makes up the chemical incompatibility between the diamond and copper, and the thermal conductivities of 40 vol.% Ti-coated diamond/Cu composites can be improved to reach 457.22 W·m−1·K−1. The results estimated by the differential effective medium (DEM) model illustrate that the thermal conductivity for 40 vol.% Ti-coated diamond/Cu composites show a dramatic decline with increasing TiC layer thickness, giving a critical value of ~260 nm.

The development of rural ethnic culture resources is conducive to protecting the cultural characteristics of traditional ethnic villages and achieving the great goal of the industrialized utilization of rural cultural heritage resources as well. Oriented by the goal of rural revitalization, this article targets the characteristics and problems of the development of the Tujia village of Feng Xiang Xi in Guizhou Province. Employing the methods of field investigation and cultural gene identification, this paper analyzes the cultural genes of the Tujia ethnic identity and summarizes the characteristics of its spatial representation. It is essential for us to summarize the current difficulties of rural protection and development and clarify the relationship between cultural revitalization, rural revitalization, and sustainable development, which then puts forward a new path for rural revitalization, especially by virtue of the inheritance of the spatial cultural genes of the Tujia village. Specifically, the “protection of the cultural genes of the Tujia ethnic identity” is determined as the principal policy for rural development, the rural spatial structure is reconstructed based on the study tour of the Tujia village, and the public cultural space is reconstructed based on the inheritance and utilization of the cultural genes of Tujia. In the meantime, attention should be paid to orderly construction, and priority should be given to the construction of transportation and service facilities. Finally, it is expected that the research can provide an implementation path for rural revitalization with distinctive ethnic cultures.

Our cities are on the verge of a radical transformation, a revolution driven by smart city technology from tranportation, engery, water supply to intelligent construction. Infrastructure is the backbone of cities and its relevant policy plays an essential role in the development of smart city. The appraisal for the policy is indispensable, however, which is often ignored. The research attempts to explore appraisal of major infrastructure policy of the UK through scenario-based multicriteria analysis (SMCA) and discuss impact of major infrastructure policy and projects on social, ecnomic, and enviroment factors of cities. This paper finds different scenarios can be incorporated into multi-criteria analysis (MCA) to investigate future uncertainty for the policy statement appraisal. However, the hybrid approach through combining scenario planning and MCA increases the complexity of the sustainability appraisal. Although more and more research has focused on comparing the strengths and weaknesses of SMCA and existing methods, the research results in the paper provide evidence that SMCA might be a more useful tool in appraising major infrastructure planning policy and projects of smart city in the furture.

With the rapid development of cities and the rapid increase in automobile ownership, traffic has become one of the main sources of PM2.5 pollution, which can be reduced by road greening through sedimentation, blocking, adhesion, and absorption. Using the method of combining field monitoring and ENVI-met simulation, the influence of the tree height on the PM2.5 concentration on both sides of the city streets was discussed. The influence of tree height on PM2.5 under five conditions was analyzed, including 10 m tall trees (i), 15 m tall trees (ii), alternating distribution of 15 and 10 m tall trees (iii), 5 m tall trees (iv), no trees on either side of the road (v). The results show that: Roadside trees can increase the concentration of PM2.5 in the narrow space of street canyons. However, without roadside trees, PM2.5 from traffic sources is not reduced in time, it is more easily spread to the distance. When the height of the roadside trees is 5 m and their crown widths are smaller than those of other trees, there is a relatively wide space between them. Compared with the higher roadside tree models with larger crown widths, the concentration of PM2.5 on the roadway and the downwind sidewalk is relatively low. In the three models (i–iii) with tree height above or equal to 10 m, the PM2.5 concentration around the trees do not show regular change with the change in tree height. Due to the tree height of 10 and 15 m, the crown width is large enough, and the alternate distribution of tree height of 15 and 10 m fails to make the PM2.5 concentration in the models lower than the models with tree height of 15 m or 10 m. The reasonable height of roadside trees in street canyons helps improve the wind circulation to promote the diffusion of PM2.5 pollution. There is no optimal height of roadside trees for PM2.5 pollution in street canyons, thus it is necessary to select the height reasonably according to the specific situation.

This paper will study the anatomy of the decision making of Hong Kong Section of Guangzhou-Shenzhen-Hong Kong High Speed Rail (XRL). The paper will focus on five aspects. They are drivers of megaprojects, mega infrastructure project as an agent of change, early and effective stakeholder engagement, Iron Triangle and context awareness. XRL will be regarded as a resonance test of the international literature findings.

The traditional medical splint has been used to fix fractures for many years. It can only rely on the doctor’s experience to control the pressure which will directly affect the rehabilitation process of the fracture. A set of intelligent medical splints that can automatically detect pressure and body temperature is proposed in this paper. Firstly, wide splint which is one of the traditional four splints used for radial fracture fixation is redesigned and printed by 3D printing technique. On the basis of ergonomics, the splint adds high-density ventilation holes, the groove of the tie wire, contact points of sensor, groove of circuit and battery. Secondly, the pressure sensor was selected and the circuit was designed. The circuit can detect several channel of pressure and one channel of temperature, simultaneously. Furthermore, the smart splint can display the pressure and temperature values locally on an OLED display screen, and can also upload data to a mobile phone using Bluetooth. After using big data analysis of patient rehabilitation data, it can be find a better treatment plan for the fractures.

Aiming at the problem that in the tradition double-coil resonance wireless power transmission system, the receiving coil misalignment in the center of the transmitting coil, resulting in a rapid decline in transmission effect. This paper creatively proposes the double D-coil wireless power transmission system, and compared with the traditional two-coil WPT system, a series of experiments have been designed. The results show that when the double D-coil system moves along the y-axis, a higher S21 value can be obtained and it will not decrease significantly with the offset. The S21 value in the X-axis direction is also higher than that of the tradition two-coil system.

The parameters of class E power amplifier are optimized for achieving zero voltage switching (ZVS) condition in the magnetically coupled resonance wireless power transmission (MCR-WPT) system. Considering that the working frequency of MCR-WPT is very high, the influence of the parasitic capacitance of the MOSFET can't be neglected. The optimized value of capacitor and inductor are obtained by circuit theory. The performance of the ZVS with the optimized value is verified with circuit simulation by evaluating the output power and efficiency of MCR-WPT system. Under the condition that the coupling coefficient (k) is 0.3, the transmission efficiency of the WPT system was as high as 87%, which was increased by more than 20% on the original basis.

A liquid-solid separation technology (LSS) is applied to fabricate near-net shape packaging shells made of hypereutectic Al-Si composites with gradient distributions of the microstructure and properties. This new technology solves the problem of the formation of coarse flake primary Si, which will seriously deteriorate the mechanical properties of the materials, and unavoidable with conventional casting method. The microstructure of the hypereutectic Al-Si composite were characterized using scanning electron microscope, energy dispersive spectroscopy and transmission electron microscope. In order to eliminate the influence of crystal defects and stress, the effects of annealing treatment on the thermal expansion coefficient and thermal conductivity of the composites were also investigated. The results show that the volume fraction of Si decreases along a gradient from the bottom centre of the packaging shell, which houses the chips, to the top of the packaging wall, which is welded with the cover materials. The bottom of the shell has a CTE of 11.7 × 10−6 K−1, TC of 124.3 W m-1 K-1, and primary Si content of 53.7%. The top of the shell has a CTE of 18.4 × 10−6 K−1, TC of 151.2 W m-1 K-1, and primary Si content of 23.3%. Such a distribution enables a good matching of the thermal expansion behaviour of the packaging shell with the chips, which have typically low CTE, while avoiding the issue of poor soldering performance of Al/Si alloys. In addition, it reduces the internal stress of the shell due to integrated forming technology.

Diamond/Al composites have been considered as the new generation of thermal management material. The critical challenge is that Al4C3 with deteriorating properties is easily generated at the interface of composites by conventional powder metallurgy and infiltration processes. This paper presents an independently developed liquid-solid separation (LSS) technology for fabricating diamond/Al composites with Cr-coated diamond particles. The key parameters of the LSS process such as the blank heating rate and its heating mode, the squeeze casting temperature and pressure, and pressurization time were optimized. Cr coating of the diamond particles led to improved interface characteristics. The higher thermal conductivity of diamond/Al composite with Cr-coated diamond particles is attributed to the favorable interfacial products of Al13Cr2 and AlCr2. Thermal conductivity of 40 vol.% Cr-coated diamond particles reinforced diamond /Al composites prepared by LSS with the optimal process was 309.20 W m−1 K−1, 108.06 % higher than that of the composite without the Cr coating. The results showed that relative density is a critical factor in optimizing of the bending strength, compressive strength, and thermal conductivity of the composites. No harmful intermetallic Al4C3 is generated at the interface of the composite. LSS technology is the new low-cost and compact method for the fabrication of diamond/Al composites with high thermal conductivity, which has the prospect of industrial application.

Megaprojects are defined as projects that cost a billion US dollars or more at 1990 prices. Mega transport infrastructure projects have the potential to affect important socioeconomic and territorial changes. They are often perceived as critical to the “success” of major metropolitan, regional and national development. The redevelopment of neighbourhoods offers many opportunities for regional regeneration, yet there remain concerns regarding the potential gentrification of areas leading to the displacement of existing populations and local businesses. This research applies multi-criteria analysis, a tool that is widely used in mega infrastructure project appraisal using the UK’s Crossrail as a case to explore the likelihood of gentrification and the displacement impacts of the project. This paper finds both positive and negative impacts. Different stakeholders express noticeably differing opinions regarding the project.

Low-cost and good quality Al–diamond composites were prepared in the application of heat dissipation using an advanced liquid–solid separation technology. Their thermal conductivity (TC) and coefficient of thermal expansion (CTE) were measured, especially on the effect of diamond particle surface metallization. The TC of composites reinforced with Ni-coated diamond particles was found to have increased by almost 80 % compared to that of Al alloys. The diamond surface in the composites was characterized using an electron microprobe, X-ray diffraction and SEM. It was found that high TC of the composites was obtained due to the generation of Al4Ni3 and AlNi phases at their interfaces between Al and diamond. In addition, the theoretical calculation for TC and CTE of the composites show the similar tendency with their experimental data.

TiO2 holds great promising for addressing the environmental issues via solar-to-chemical energy conversion. However, the large-scale application is greatly limited by its poor optical response (below 400 nm). In this study, we have successfully synthesized a visible light driven TiO2 catalyst via a facile hydrothermal route by using amidoximated polyacrylonitrile (PAN) fiber as the support for the first time. The fibrous bidentate ligands not only facilitated the visible light harvesting of TiO2 through ligand-to-metal charge transfer (LMCT) sensitization but also realized the incorporation of N atoms into the TiO2 lattice during the preparation. Such a unique architecture endows the TiO2 with high photocatalytic activity for degradation of several emerging organic contaminations under visible light irradiation (λ > 420 nm), which is dictated by both LMCT and N-doping mechanism. Furthermore, the fibrous support shows high resistance to active oxidizing species and imparts the as-prepared catalyst with excellent cycling stability, demonstrating the robustness of the constructed photocatalytic system for long-term applications. Our findings may offer a new strategy for designing promising visible-light-driven photocatalysts for environmental remediation.

Fe-based composite coating prepared onto the component of guide wheel using ultrasonic frequency inductive cladding (UFIC) technique has been investigated in terms of microstructure, phase constitutions, microhardness and elevated temperature wear behavior by scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS), X-ray diffraction (XRD), Vickers microhardness tester and ball-on-disc wear tester. The results indicated that the primary phase in the coating contained austenite γ-Fe, eutectic γ-Fe/(Cr,Fe)2B, boride (Cr,Fe)2B and precipitation enriched in Mo. The average microhardness of the coating was 760 ± 10 HV0.2, which was three times higher than that of the substrate. With increasing temperature, the friction coefficients of the coating and high-chromium cast iron decreased gradually while the wear rates increased during dry sliding wear condition. The relative wear resistance of the coating was 1.63 times higher than that of the high-chromium cast iron at 500 °C, which was ascribed to the hard borides with high thermal stability uniformly embedded in the coating and the formation of dense transfer layer formed onto the worn surface. The high temperature wear mechanism of the coating was dominated by mild abrasive wear. The study revealed that Fe-based composite coating had excellent high temperature wear resistance under dry sliding wear condition.

Induction melted FeCrB metamorphic coatings deposited onto Q235 steel were produced using ultrasonic frequency inductive cladding (UFIC) technique. The measurements of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS), transmission electron microscopy (TEM), microhardness tester and ball-on-disc wear tester were used to determine the microstructure, microhardness and dry-sliding wear resistance coupled with wear mechanism of clad coatings. The experimental results show that C+ clad coating consists of austenite γ-Fe, interdentritic lamellar eutectics γ-Fe/(Cr,Fe)2B and borides (Cr,Fe)2B as the reinforcing phase whilst the phases of ferrite α-Fe, borides Cr1.65Fe0.35B0.96 and eutectics α-Fe/Cr1.65Fe0.35B0.96 are identified in M clad coating. The average microhardness of the C+ and M clad coating is more than 3-times than that of the substrate. The wear resistance of the C+ and M clad coating improves 5.18, 6.08 times compared with that of the substrate at applied load of 20 N, respectively, which contributes to the occurrence of the crystalline–amorphous phase transition by friction treatment and uniformly distributed borides embedded in the ductile solid solution matrix.

Two kinds of induction melted Fe-based alloy coatings with chemical compositions (in wt.%) Fe–30.4Cr–3.5B–3.1Si–20.3Ni–8.7Co–3.6Mo–2.7Cu (C +) and Fe–44.1Cr–5.6B–4.7Si (M) deposited onto Q235 steel by ultrasonic frequency inductive cladding (UFIC) technique have been investigated in terms of microstructures, phase composition, microhardness and corrosion behavior by SEM/EDS, XRD, Vickers microhardness tester and Raman spectroscopy analyses. The results showed that four morphologies of austenite γ-Fe, eutectics γ-Fe/(Cr,Fe)2B, borides (Cr,Fe)2B and precipitations enriched in Mo contained in the C + coating whilst ferrite α-Fe, borides Cr1.65Fe0.35B0.96 and eutectics α-Fe/Cr1.65Fe0.35B0.96 were identified in the M coating. EDS line analysis of the interdiffusion zone indicated that element Fe decreased from the substrate into the coating while that of Cr and Si was in the reverse due to the dilution of the substrate. The average microhardness value of the M coating was higher than that of the C + coating, which was ascribed to the higher volume content of borides uniformly dispersed in the matrix. Due to the formation of the protective oxidation layer formed onto the coating, the corrosion resistance of both coatings increased over one order of magnitude compared with the substrate by the immersion and electrochemical tests in a 3.5 wt.% NaCl solution.

By means of Monte Carlo (MC), the process of the nitrogen ion implanting in the titanium was simulated, which occurred during the nitriding titanium by laser and plasma nitriding (LPN). The nitrogen ion distribution in the titanium, the biggest penetration depth, and the thickness of the nitriding layer were calculated at different laser power density. Under the conditions, P 0 = 1.0 × 10 6 W/cm 2 (laser power density) and v = 200 mm / min (scanning velocity), the simulated results were in good agreement with the corresponding experimental results. The simulations predicted that, when v = 200 mm / min and 2.0 × 10 5 W/cm 2 ≤ P 0 ≤ 1.0 × 10 6 W/cm 2 , the penetration depth increased with the laser power density increasing. A better nitriding effect could be obtained when the laser power density was higher than 8.0 × 10 5 W/cm 2 .

Thermal stability of iron nitrides prepared by mixing laser and plasma beam nitriding (LPN) technology was studied. The treated samples were annealed in vacuum at different temperature from 473 K to 1273 K. The phases were detected by X-ray diffraction (XRD), the nitride’s contents were calculated from the patterns of XRD, and the microstructures were analyzed by scanning electron microscope (SEM). Three critical temperatures (473 K, 673 K, and 1273 K) are found. Due to deeper nitriding layer in the LPN sample, the nitrides is more stable than that in laser-produced sample at the annealing temperature higher than 973 K. It is important and central for some potential industrial productions and applications.

The magnetic behavior of a mixed Ising ferromagnetic system on Fe4N expended face-center cubic lattice, with single-site anisotropy, has been studied with Monte Carlo Simulation. The expended face-center cubic lattice was divided into one simple cubic lattice composed of Fe(I) at the corner site and three inhomogeneous simple cubic lattices composed of Fe(II) at the face-centered one. The two sublattices have spin-3/2 and spin-1, respectively. The model includes nearest interactions and single-site anisotropy terms. By studying magnetization, internal energy, specific heat of this model at different temperatures, we found that the absolute zero value of magnetization is changed by existence of Fe(I)'s and Fe(II)'s crystal-field interactions (D1, D2). The final value of internal energy is different for different D1 and D2. Curie temperature is increasing with the increase of D1 and D2. Especially, equal point of sublattice magnetization was recognized, when D1 was changed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A program is modeled to describe nitriding depth by a new mixing laser and plasma beams nitriding (LPN) technique. The model extends the transport of ions in matter (TRIM) program by adding temperature and energy factors into the energy function. The nitriding depths and nitrogen distribution in substrate were calculated by Monte Carlo program. There is a good agreement between calculation and experiment results at different laser energy intensities, scanning velocities and nitrogen ion energies respectively. Moreover, the nitriding process diagrams by LPN technique are shown from calculation results.

Iron nitride (FexN) is obtained by the mixing technology with laser and plasma beams coaxially on the surface of pure iron in atmosphere. In this technology, laser and plasma provide heat source and nitrogen ion source, respectively, easily to nitriding the sample. The feasibility of the method is analyzed in theory. Small-angle X-ray diffraction measurements reveal formation of iron nitride in the as-treated sample, and scanning tunneling microscope measurements describe the surface profiles of the irradiated area, at different laser energy densities or different scanning velocities.

In this work, the nitrogen molecular dissociation and ionization levels in Ar/N 2 flue plasma are evaluated as functions of plasma parameters such as Ar mixture quantity and N 2 flux in order to obtain the best condition for various applications such as thin film deposition and material surface modification. This plasma is operated at 10 kV and the nitrogen dissociation rate is determined by analyzing the optical emission of the nitrogen band. For different operating conditions, the dissociation rate [N] of N 2 molecules was enhanced, as the mixture quantity of Ar increased from 0.06 m 3 /h to 0.9 m 3 /h and the max of enhancement factor is 4.3. This factor becomes bigger when the N 2 flux becomes bigger. Moreover, the molecular nitrogen ionization density is calculated from the current intensity of the plasma. The ionization density was also enhanced, as the mixture quantity of Ar increased from 0.1 m 3 /h to 1.5 m 3 /h, under three different voltages. The max of enhancement factor of 1.96 is much smaller than the factor of the dissociation rate. These results are discussed in terms of the kinetics of the electrons, nitrogen ions, atoms and molecules.

Laser nitriding is an attractive method to improve metal surface properties, such as hardness, wear, and corrosion resistance, with the advantage of simple experimental setup, rapid treatment, and precise process control. Here, iron nitride (FexN) is obtained by the mixing technology with laser and pre-heated nitrogen (LHN) or nitrogen plasma (LPN) beams on the surface of pure iron in atmosphere ambient. In these two technologies, laser provides heat, pre-heated nitrogen provides help for nitrogen activity, and nitrogen plasma provides nitrogen ions, respectively. The two technologies are superior to the previous laser nitriding (LN) methods. However, iron nitride more difficult was obtained by the mixing technology with laser and pre-heated nitrogen than by the mixing technology with laser and plasma, and iron oxide was not observed in the sample treated by the latter. The feasibility of the technologies is analyzed in theory. X-ray diffraction measurements reveal formation of iron nitride in the as-treated sample by these technologies. Moreover, the concentration and phase formation of iron nitride were given at different laser power densities and different scanning velocities with emphasis on the mixing technology with laser and plasma.

Using Monte Carlo methods, we investigate the magnetic properties of a mixed spin-3/2 and spin-1 Ising ferromagnetic system on an expanded FCC lattice in Fe4N. In particular, the expanded FCC lattice was divided into one simple cubic lattice composed of Fe(I) at the corner site and three inhomogeneous simple cubic lattices composed of Fe(II) at the face-centered one. The effect of the next-neighbor exchange interaction of Fe(I), the next-neighbor exchange interaction of Fe(II), and the exchange interaction of Fe(II) due to the nitrogen atoms was studied. The magnetization, internal energy and specific heat curve, and the phase diagrams are given. We found that the transition temperature and magnetic moment increase with the increase of the exchange interaction of next-nearest atoms Fe(I), Fe(II), and the exchange interaction between Fe(II) via nitrogen atoms. It is because of the exchange interaction due to the nitrogen atoms that Fe4N has a higher saturation magnetization than pure iron. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The magnetic properties of a mixed spin-32 and spin-1 Ising ferromagnetic system on an expanded FCC lattice in Fe4N are studied. In particular, the expanded FCC lattice was divided into one simple cubic lattice and three inhomogeneous simple cubic lattices in Monte Carlo simulations. We investigate the effect of the next-nearest atom and the nitrogen atom on the phase diagrams and critical behavior, in order to clarify the characteristic magnetic features observed in Fe4N. The magnetization, internal energy and specific heat curve and the phase diagrams are given. We found that the transition temperature and magnetic moment increase with the increase of the exchange interaction of next-nearest atomic and the exchange interaction between Fe (II) (at the face-centered one) via nitrogen atomic. It is because of the exchange interaction due to the nitrogen atom that Fe4N has a higher saturation magnetization than pure iron.

The fabrication processes of metal matrix composites are very important for their application. There are many kinds of processes used, such as the squeeze casting process, the vacuum-high pressure infiltration process and the stirring casting process. In this article a new brief process for the fabrication of particle reinforced metal matrix composites will be introduced that has been used for silicon particulate reinforced Al-based composite and zinc-based composite. This process is the rheological compocasting process of a multicomponent system, in which a part of the raw materials mix with the rest where the latter are in the form of semi-solid moltens. The primary phases that are in the semi-solid molten material are left and are used as reinforcement phases. The tests show that the process is feasible, convenient and practical.

Al Si alloy is one of the most widely applied commercial alloys. Its properties can be improved by alloying with the element silicon, the morphology of the silicon phases having a direct effect on its properties. The modification of the needle-like eutectic silicon and plate primary silicon phase is importance for the mechanical properties of Al Si alloy. Zinc based aluminum alloy is also an important commercial alloy, one of its main applications being that of a wear-resistant material. It is composed of multiphases, but the microhardness differences of each phase is not great. If the number of dispersion hard phases (or particles) is well-distributed in the zinc based aluminum alloy, it is of no doubt that the abraiibility of the material is improved. The problem of how to prepare particle reinforced zinc based aluminum alloy composite is of concern to researchers. The purpose of this present study is to introduce a new process which can be used to prepare silicon particle reinforced zinc based aluminum alloy composite. The process is that the molten zinc based aluminum alloy mixes with rheologic (or semi-solid) hypercutectic Al Si alloy, the primary and eutectic silicon phases then acting as a particle reinforced phase in the zinc based aluminum alloy. The morphology of silicon phase can be controlled by stirring and modifying. The morphology of the silicon phase is regularly polyhedral, its size is about 10≈50 μm and it is well-distributed in the zinc based aluminum alloy. The results of wear-resistant test show that the silicon particle reinforced zinc based aluminum alloy composite is a good wear-resistant material.

The interfacial reactions of oxidized SiC particles reinforced Al-Mg matrix composites were investigated by the field emission-scanning electron microscopy (FE-SEM), TEM and X-ray diffraction. It was found that the nanoscale MgO forms initially due to the interfacial reaction, then whether it reacts with molten Al continuously or not depends on the content of Mg in the matrix and its covering densification at the surface of particles. When there is not enough Mg in the matrix for the formation of dense MgO layer, MgO will transform into MgAl2O4 crystal owing to the continuous reaction with SiO2 and molten Al. When dense MgO layer forms at the surface of the particles due to the affluence of Mg for the initial reaction, it will protect the inner SiC from the attack of molten Al. However, the reaction products of both MgO and MgAl2O4 are thermo-stable phases at the surface of the particles under high temperature. The results clarify the interfacial reaction route and they are of great value to the control of the interfacial reactions and their interfacial design of the composites.