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The solidification process and microstructure of Al-7Si-0.3Mg alloy with different rare earth (RE) additions have been studied by using thermal analysis, optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The results showed that the addition of RE enhanced the liquidus temperature and decreased the growth temperature of eutectic Si, which lead to obvious increase in solidification interval of the studied alloy. In addition, the grain size of primary α-Al had no obvious change, and the mean area of eutectic Si particles decreased with increasing RE content to 1.6 wt.%. The RE-rich compounds with different compositions were obtained with increasing RE concentration in Al-7Si-0.3Mg alloys. The method of phase diagram calculation helps to clarify the formation and growth mechamism of different RE-rich phases during solidification.

Semi-solid aluminum slurries have globular grains, different from traditional dendritic solidification microstructures. The mechanism responsible for the formation of these globular grains is still in dispute. Some researchers suggest that the globular grains are formed by fractured dendrites, while others report it is due to copious nucleation. This study will model the growth of the α-Al phase during the production of semi-solid slurries using the swirled equilibrium enthalpy device (SEED) process, where liquid alloy with a low superheat is poured into a steel crucible and swirled within the semi-solid region. Experimental observations have shown that the final microstructure of the slurry produced by the SEED process is relatively non-uniform, with large dendrites at surface and fine spherical particles at the center. Open source code for the phase field method has been adopted to simulate the different microstructural evolution for semi-solid alloy 357.0. The effect of localized temperatures under isothermal condition on the morphology of the α-Al particles has been investigated according to the special conditions of the SEED process. In addition, suggestions for modifying the slurry production to achieve more uniform microstructure are discussed.

Microstructures with fine globular grains and refined eutectic structures are important to enhance the mechanical properties of A356 alloys processed by semi-solid and gravity die casting. Rare earth (RE) additions have been shown to be capable of refining both the α-Al particles as well as modify the eutectic phase of alloys. In semi-solid die casting, Al7Si0.3Mg alloys with RE concentrations (0, 0.1 and 0.4 wt.%) were used to prepare semi-solid slurries using the SEED (Swirling Enthalpy Equilibrium Device) method, and subsequently semi-solid die cast. The same compositions of alloys were also applied to gravity die casting. The microstructure and mechanical properties of castings in two processes have been characterized. Compared to the grains produced in gravity die casting, globular grains with small size (260 μm) in the semi-solid die casting significantly enhance the UTS and elongation of alloys. Although the size of grains had no change with increasing RE concentrations in alloys. The Al-Si eutectics were changed to refined morphology with the 0.1 wt.% RE addition, which enhanced the ductility of alloys in two processes. When increasing the RE addition to 0.4 wt.%, the RE-rich phases precipitated at grain boundaries, which decreased the UTS and elongation of alloys.

Laser additive manufacturing (LAM) technology was applied to prepare Ti-22Al-25Nb alloy thin-wall sample. The characteristics and evolution mechanism of solidification microstructure were investigated, and the tensile properties at horizontal and vertical directions were discussed. The results indicated that the solidification microstructure in single deposition layer evolved as: plane crystal structure, cellular crystal structure, columnar dendrite structure and equiaxed dendrite structure, from the bottom to the top of the molten pool. During the solidification process, the temperature gradient and solidification velocity decided the grain growth morphology. However, the grain of the as-deposited materials grew up to thick equaxied structure when the upper layer was forming. The tensile properties at horizontal and vertical directions were not much different, both of these exhibited high strength and low ductility.

The approximately equimolar ratio AlCrNiSiTi multi-principal element alloy (MPEA) coatings were fabricated by laser cladding on Ti–6Al–4V (Ti64) alloy. Scanning electron microscopy (SEM), equipped with an energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) were used to characterize the microstructure and composition. Investigations show that the coatings consist of (Ti, Cr)5Si3 and NiAl phases, formed by in situ reaction. The phase composition is initially explicated according to obtainable binary and ternary phase diagrams, and the formation Gibbs energy of Ti5Si3, V5Si3 and Cr5Si3. Dry sliding reciprocating friction and wear tests of the AlCrNiSiTi coating and Ti64 alloy substrate without coating were evaluated. A surface mapping profiler was used to evaluate the wear volume. The worn surface was characterized by SEM–EDS. The hardness and wear resistance of the AlCrNiSiTi coating are well compared with that of the basal material (Ti64). The main wear mechanism of the AlCrNiSiTi coating is slightly adhesive transfer from GCr15 counterpart, and a mixed layer composed of transferred materials and oxide is formed.

Laser powder deposition was applied to fabricate the Ti–6.5Al–3.5Mo–1.5Zr–0.3Si (wt%)/Ti–47Al–2Cr–2Nb–0.2W–0.15B (at%) bi-material system. The as-deposited TC11 alloy shows a basket-wave-like morphology while the as-deposited γ-TiAl alloy consists of fully α2/γ lamellar microstructures. Regarding the thermal mismatch between TC11 and γ-TiAl during processing, the interface microstructure evolution was concerned. The transformation pathway was illustrated. It is found that the content changes of Al elements and β-stabilizers Mo, Cr, and Nb are responsible for the evolution of microstructures at the interface. The fracture surfaces are located at the γ-TiAl side. The bi-material shows a brittle-fracture manner, with the ultimate tensile strength of 560 MPa.

There exist multi-field coupling effect in prefabricated defects polymer materials under loading. For understanding the pyromagnetic effect, it is crucial to accurately measure the coupling relations of the key physical quantities about displacement, tensile load, temperature, and magnetic field. To overcome the obstacle in current measurement systems for synchronized measurement, an integrated measurement system for multi-field coupling detection is presented to enable synchronized, automatic detection. This paper introduces the system structure, software design, and the detailed design of varied-speed PID control methods. Test results show that, the system is effective for valid data acquisition for displacement, tension load, temperature and magnetic field of a high polymer Polyvinyl Chloride (PVC) plate sample under constant tensile load, and all test data can be visualized on the software interface. This system provides a good test platform for further research on pyromagnetic effect of PVC plate.

A numerical model of carrier saturation velocity and drain current for the monolayer graphene field effect transistors (GFETs) is proposed by considering the exponential distribution of potential fluctuations in disordered graphene system. The carrier saturation velocity of GFET is investigated by the two-region model, and it is found to be affected not only by the carrier density, but also by the graphene disorder. The numerical solutions of the carrier density and carrier saturation velocity in the disordered GFETs yield clear and physical-based results. The simulated results of the drain current model show good consistency with the reported experimental data.

Understanding the effect of process parameters on microstructure is crucial to control or optimize microstructure for laser direct deposition process. Four thin-wall samples of TC11 titanium alloy are deposited with different process parameters. They showed different macro/micro-structure and mechanical properties. The reason is analyzed by temperature field of samples which are simulated by ANSYS software. Results show that, deposition with low laser power and slow scanning speed is conducive to reducing molten pool temperature and soaking time in β-phase region, refining original β grain and improving the plastic properties of the deposited parts. Deposition with high laser power and rapid scanning speed, combined with interlayer stay, is helpful to increase the cooling rate within α+β phase region, refine intragranular α lamellar and improve the tensile strength of deposited parts.

Powder transport ratio is defined as the mass ratio of powder particles fed into the molten pool to all powders transported in the process of laser cladding by lateral powder feeding. According to the law of mass conservation and kinematic equation in physics, a powder transport model for flow field with cylindrical distribution and a mathematical expression of powder transport ratio are proposed. For different process parameters, the cross-sectional area of the clad layer is calculated by the model. Theoretical and experimental results are compared. The variation tendency of the theoretical cross-sectional area agrees well with the experimental results. The results indicate that the powder transport model can be used for fundamental research of real powder flow field.

In a deformation progress of a polyvinyl chloride sheet, the coupled deforming heat is recorded by a thermal infrared imager. In order to have a real-time study for the variation regularity of the deforming temperature field distribution, all infrared images are imported into MATLAB software as digital data through a dynamic link routine compiled based on MATLAB and Windows. By utilizing a gradient-based transition region extraction algorithm and an interpolation algorithm, the high-resolution recognized and reconstructed infrared images are obtained from original blurring images recorded in thermal infrared imager. The variations of temperature distribution are studied combining with the test data based on MATLAB.

Due to the promising properties of high entropy alloy, TiVCrAlSi high entropy alloy coating was prepared on Ti-6Al-4V alloy surface by laser cladding. The microstructure and phase analysis of as-cast TiVCrAlSi alloy and laser clad coating were characterized by scanning electron microscope and X-ray diffraction. The results indicate that as-cast TiVCrAlSi alloy is mainly composed of (Ti,V)5Si3 and bcc phase. The laser clad coating is metallurgically bonded to the substrate with few pores and cracks. Laser clad TiVCrAlSi coating is also composed of (Ti,V)5Si3 and bcc phases.

The total load on a crank bearing was calculated by performing a load analysis of the crank connecting rod mechanism. The Reynolds equation for hydrodynamic lubrication of the crank bearing was established at the Reynolds boundary condition and was then solved using the Holland method. From this the regular track of the bearing axis was obtained. As the crank bearing gradually wears the eccentricity ratio corresponding to the minimum oil film thickness increases gradually. The oil-bound film eventually breaks down, which allows friction and collision between the metal surfaces of the crank pin and the bearing. The rigid impact leads to excitation of high frequency vibrations at the natural frequencies of the connecting rod. The experiments show that the wear condition of the crank bearing can be identified correctly through the vibration signature at the natural frequencies of the connecting rod. The degree of wear can be predicted accurately through the energy content of the high frequency bands.