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Lead‐free polycrystalline manganese telluride holds great potential in the development of waste heat recovery due to its fascinating physical properties. However, the poor thermoelectric (TE) performance in the p‐type MnTe alloys always results from their inferior carrier concentration, leading to low power factor and high thermal conductivity which restrict the overall thermoelectric performance. In this work, the problem is solved by decoupling its electrical and thermal transports through the hole donor Ge‐deficiency in MnTe + x mol.% GeTe (0 ≤ x ≤ 4) compounds. Intrinsically, extra GeTe in MnTe + x mol.% GeTe compound offers free charge carriers due to a narrow bandgap comparatively, realizing not only a full assessment of stimulated electrical performance but also an enhanced power factor. Moreover, benefiting from the nano‐precipitates and tweed microstructures, the lattice thermal conductivity effectively reduces due to the intensive phonon scattering accordingly. Ultimately, a maximum ZT of ≈1.2 at 873 K in the 3 mol.% GeTe doped MnTe sample is realized. [ABSTRACT FROM AUTHOR]

Duplex stainless steel (DSS) is widely used in the marine, petroleum, chemical, automotive, and other fields owing to its excellent mechanical properties and corrosion resistance. However, the research on duplex stainless steel prepared by additive manufacturing is still limited. In this paper, high-density 2507 DSS was successfully prepared by selective laser melting (SLM) additive manufacturing. The effects of energy density on the formability, phase composition, microstructure and corrosion properties of SLM 2507 DSS were investigated. The results showed that with the decrease of the energy density, the density of the specimen increases first and then decreases, and the density achieves 99.18% with the energy density of 190.5 J/mm3. The types of phases are not affected by the energy density, i.e., all 2507 DSS samples prepared by SLM showed a ferrite phase. The YOZ (parallel to the building direction) plane of the SLM 2507 DSS samples showed predominantly columnar grains attributed to the high temperature gradient and epitaxial growth characteristics. With the increase of energy density, the average grain size decreases slightly from 16.97 μm to 15.78 μm, the KAM value decreases slightly from 1.15 to 1.05, and the low angle grain boundaries (LAGBs) increase significantly from 68.4% to 74.8%. The SLM 2507 DSS sample exhibited excellent corrosion resistance. The self-corrosion potential of the sample is 136 mV and the self-corrosion current density is 2.066 × 10−8 A/cm2 at the maximum density. This investigation provides a new approach for the preparation of super duplex stainless steel, which can provide a theoretical basis and guidance for industrialized application.

In order to further improve the comprehensive mechanical properties of commercial AZ31 Mg alloy, AZ31/graphene nano particulates (GNP) composites were prepared by AZ31 Mg alloy and graphene through friction stir processing (FSP) and following rolling. The microstructure and mechanical properties of as-FSPed and as-rolled alloys were investigated in this study. Compared with base metal, the ductility of FSPed alloys is greatly increased, while the strength is somewhat decreased. After further rolling on the FSPed plate, the strength of the alloy is improved. AZ31/GNP composites processed by FSP and rolling (50% reduction ratio) exhibits excellent mechanical properties with ultimate tensile strength of 296 MPa and elongation of 15.7%. The improved performance is attributed to the refinement of the grain and the homogenization of the second phase, which are the result of the severe plastic deformation characteristics of FSP. The multiplication of dislocations originated from rolling deformation and the reinforcement of GNP also contribute to the strength. The results verify that FSP as an intermediate step before rolling can be used as an effective mean to add reinforcement particles. On the other hand, the improved microstructure induced by severe plastic deformation of FSP is beneficial for further rolling.

Experimental study of laser proton acceleration was carried out using laser machined line targets and cross targets with tens of micrometers scale. We have found that both the shape and material of the microstructure targets have significant influences on the distribution of the proton beam. For the aluminum line target, the proton beam spot expands in a direction perpendicular to the boundary of the target; while for the plastic line target, it expands parallel to the boundary of the target. Detailed PIC simulations of the aluminum target have been carried out, which show that due to the lateral transport of hot electrons and the sheath fields accumulated at the edge of the microstructure target, the divergence angle of the accelerated proton beam is changed accordingly, thereby modulating the spatial distribution: the elliptical beam spot can be obtained from the line target, and the quasi-square beam spot can be obtained from the cross target. Simulations of the plastic target indicate that the difference in the electron transport properties for the two types of targets may be the reason for the completely different beam spot shapes. This work shows that the microstructure targets can be a potential method to manipulate the spatial distribution and uniformity of the proton beam. [ABSTRACT FROM AUTHOR]

FeCoNiAlCrx(x=0, 0.2, 0.4, 0.6, 0.8, atomic ratio) high-entropy alloy ingots were prepared by vacuum arc melting method, and the effect of Cr content on the microstructure and mechanical properties of the alloy was investigated. The phase structure, microstructure and the composition of the alloy were analyzed and characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS).The compression properties of the alloy were tested by universal testing machine. The results show that with the increase of Cr content, the microstructure of the alloy changes from a single-phase BCC structure to a BCC+FCC mixed structure; the microstructure of the alloy gradually changes from an equiaxed structure to a dendrite structure, and the grain size of the alloy is obviously refined. The five alloys prepared in this experiment have relatively good mechanical properties, and the compressive strength of the alloy increases greatly with the increase of Cr content. When x=0, the compressive strength and plastic strain of the alloy are the lowest, which are 1500 MPa and 13.56%, respectively; when x=0.8, the compressive strength and plastic strain of the alloy reach the maximum, which are 2460 MPa and 30.09%, respectively; the compressive strength of the alloy increases by 64%. It indicates that Cr addition plays an important role in the microstructure refinement, the improvement of compressive strength and ductility of FeCoNiAlCrx high-entropy alloys.

The effect law of heat treatment process on the microstructure of GCr15SiMo steel was studied, and the dynamic and high temperature mechanical behavior of GCr15SiMo steel with different microstructure was analyzed by using Hopkinson rod and GNT100-2 high temperature tensile testing machine. The results show that the mass fraction of M3C-type carbide particles of GCr15SiMo steel decreases from 2.319% to 0% when the quenching temperature increases from 800 ℃ to 920 ℃; the failure strains of GCr15SiMo steel all increase with the increase of strain rate during dynamic compression.When the true strain is 0.2 and 0.8, the rheological stress of GCr15SiMo steel decreases by 13.45%, 21.44%, 27.49% and 31.79% respectively with the increase of quenching temperature. The accelerated decrease of rheological stress is mainly related to the structure and adiabatic shear mechanism during dynamic compression deformation; at high strain rate, the macroscopic deformation of GCr15SiMo steel changes from pier coarseness to shear failure along 45°, the adiabatic shear mechanism is one of the main reasons for the change in deformation behavior, and the structure is one of the key factors affecting the sensitivity to adiabatic shear; during dynamic compression deformation of GCr15SiMo steel, the deformation temperature rises between 117 ℃ and 333 ℃, and the M3C carbide particle re-solution is one of the key factors for the increase of tensile strength and decrease of yield strength of high temperature performance. When the quenching temperature is 920 ℃, the microstructure of GCr15SiMo steel is uniform twin martensite. The subgrain boundaries in the twin crystal martensite can effectively impede the dislocation movement, which show obvious strain hardening phenomenon under the tensile stress, and the stress-strain curve shows a more significant rising trend than that at quenching temperature of 800 ℃.

Al-Li alloy has been widely used in aerospace field attribute to the advantages of lower density, higher strength, damage tolerance and corrosion resistance. Dynamic recrystallization phenomena exist in Al-Li alloy during hot deformation. This paper overviews the dynamic recrystallization behavior occurring in hot processing of Al-Li alloy. The research history of dynamic recrystallization is summarized, together with the key factors that influencing the dynamic recrystallization processes including stacking fault energy, grain size, hot processing conditions and secondary particles. The nucleation mechanisms and conditions of discontinuous dynamic recrystallization, continuous dynamic recrystallization and geometric dynamic recrystallization are depicted and analyzed respectively, followed by a discussion on the effects of the forward three dynamic recrystallization mechanisms regarding the mechanical properties and microstructure. Ultimately, the unsolved and challenging scientific and technological issues are highlighted with some aspects desiring further exploration. It is feasible to provide ideas and inspiration for scholars to better comprehend dynamic recrystallization mechanisms during the hot deformation of Al-Li alloy with the assistance of electron backscatter diffraction and transmission electron microscopy characterization methods.

By designing several extrusion parameters, the Mg-0.12Ca-0.08Ba (wt%) alloy with dilute alloy content was processed, the microstructure and tensile property of alloys have been reasonably examined by means of electron backscattered diffraction, scanning electron microscopy and X-ray diffraction. The results demonstrate the grains of Mg-0.12Ca-0.08Ba alloys are refined after extrusion, and the alloys form uniform dynamic recrystallized grains. There are two different types of texture components in the extruded alloy, rare earth texture and extruded fiber texture, which crystallographic orientation is ∥ED and ∥ED, respectively. This “rare earth texture” component was found to be suppressed at high extrusion temperatures. The extrudants at 380 °C exhibits the best performance, its yield strength (YS) and ultimate tensile strength (UTS) are 197 MPa and 252 MPa, respectively, and the elongation-to-fracture (EL) is 33.1%. The plastic enhancement after extrusion mainly comes from grain refinement and texture weakening in the alloys.

The microstructure of 3D n-directional braided composites is established in this study. A theoretical method that considers 3D braided composites as assemblages of unidirectional composites is proposed to predict their elastic properties. A comparison of the predicted stiffness with experimental results showed their good agreement. The relationship between braiding parameters, including the braiding angle and fiber volume fraction, and the elastic constants is analyzed. [ABSTRACT FROM AUTHOR]

Cu–15Ni–8Sn alloy is the best choice to replace beryllium bronze alloy. This alloy has unparalleled application value in aerospace, ocean engineering, electronic information, equipment manufacturing, and other fields. However, the application of Cu–15Ni–8Sn alloy is challenged and limited because of a series of problems in its preparation and processing, such as easy segregation, difficult deformation, and discontinuous precipitation. It is an effective way to improve the comprehensive properties of Cu–15Ni–8Sn alloy using alloying design and process optimization to control the as-cast, deformed, and heat-treated microstructures. At present, it is a hot spot for scholars to study. In this paper, the grade generation, system evolution, and preparation technology development of Cu–15Ni–8Sn alloy are comprehensively reviewed. The phase transformation sequence of the Cu–15Ni–8Sn alloy is discussed. The influence of the type, amount, and existing form of alloying elements on the strength of Cu–15Ni–8Sn alloy and its mechanism are systematically summarized. Furthermore, the latest research progress on the effects of solid solution, cold deformation, and aging on the phase structure transformation and mechanical properties of Cu–15Ni–8Sn alloy is summarized. Finally, the future development trend of the Cu–15Ni–8Sn alloy is projected. The research results of this paper can provide a reference for the control of the microstructure and properties of high-performance Cu–15Ni–8Sn alloys used in key fields, as well as the optimization of the preparation process and alloy composition.

In this study, trace amounts of In and Ce elements were composite added into a Ag10CuZnSn low-silver brazing filler metal, and the effects of the composite alloying on the solidus and liquidus temperatures, the spreading performance, the microstructure of the filler metal, and the mechanical properties of the joints prepared with these filler metals were studied. The results reveal that the In element can significantly decrease the solidus and the liquidus temperatures of the Ag10CuZnSn alloy, while the Ce element has little effect on the melting temperature. Trace amounts of In and Ce elements can obviously increase the spreading areas of the filler metals on the pure Cu and 304 stainless steel base metals. The In and Ce elements can refine the microstructure of the filler metals. When the contents of In and Ce are 1.5 wt% and 0.15 wt%, respectively, the microstructure refinement effect is the most obvious, and the shear strength of the 304 stainless steel brazed joint also achieves a maximum value of 375 MPa. Excessive addition of In and Ce can form brittle intermetallic compounds in the filler metal, decreasing the brazed joints' shear strength.

Research on magnesium alloys continues to attract great attention, with more than 3000 papers on magnesium and magnesium alloys published and indexed in SCI in 2020 alone. The results of bibliometric analyses show that microstructure control and mechanical properties of Mg alloys are continuously the main research focus, and the corrosion and protection of Mg alloys are still widely concerned. The emerging research hot spots are mainly on functional magnesium materials, such as Mg ion batteries, hydrogen storage Mg materials, and bio-magnesium alloys. Great contributions to the research and development of magnesium alloys in 2020 have been made by Chongqing University, Chinese Academy of Sciences, Central South University, Shanghai Jiaotong University, Northeastern University, Helmholtz Zentrum Geesthacht, etc. The directions for future research are suggested, including: 1) the synergistic control of microstructures to achieve high-performance magnesium alloys with concurrent high strength and superior plasticity along with high corrosion resistance and low cost; 2) further development of functional magnesium materials such as Mg batteries, hydrogen storage Mg materials, structural-functional materials and bio-magnesium materials; 3) studies on the effective corrosion protection and control of degradation rate of magnesium alloys; 4) further improvement of advanced processing technology on Mg alloys.

S30432 steels were processed by multistep shot peening treatment. The refined microstructures, including domain size, microstrain, domain size distribution and texture were characterized by X-ray diffraction (XRD) line profile analysis method, respectively. The results demonstrate that in the deformed layers, a gradient structure is formed after shot peening. The domain size reaches 25nm at the surface, then it decreases as the depth increases, but microstrain (0.0027) is the largest at the surface. The domain size distributions at different depths calculated by Rietveld method are consistent with domain size variation along the depth. There are no strong textures after shot peening treatment. The change of microhardness along the depth is in accordance with the gradient microstructure. It is expected that this work can offer useful information for characterizing the microstructure of shot peened materials. [ABSTRACT FROM AUTHOR]

The microstructure and mechanical properties of AZ91D alloy thin-wall parts produced by the rheomolding (RM) process were investigated and compared with the same alloy formed by conventional high-pressure die casting (HPDC). The results indicate that the RM process is able to get such AZ91D parts in which α-Mg with average size of 27.36 μm are spherical and uniformly distributed in the matrix, and the matrix is a mixture of numerous fine α-Mg and intermetallic β-MgAl. High mechanical properties including ultimate tensile strength (UTS) of 270 MPa, yield strength (YS) of 169 MPa, elongation of 7.1%, and Vickers hardness of 102 are obtained in parts formed by RM due to the fine and uniform microstructure and less porosities. Compared with HPDC, the UTS, YS, elongation, and hardness of RM AZ91D are increased by 14.4, 9.7, 86.8, and 21.4%, respectively. The solidified grains in RM AZ91D alloy show a smaller aluminum gradient than that in HPDC. This indicates that the solidification of the RM AZ91D is closer to equilibrium. [ABSTRACT FROM AUTHOR]

Low ductility has always been a drawback for nanostructured materials. In this study, we applied a low-temperature annealing process on a cold rolled Al-8.1Mg-0.15Zr alloy with supersaturated state. It is found that the uniform elongation of the rolled specimen was improved by 124% after a low-temperature annealing treatment at 333 K, while an enhanced tensile strength was obtained in the annealed specimen. The good combination of tensile strength and ductility was mainly attributed to the fully nanostructured microstructure and the formation of nanoscale precipitates and segregation of Mg element after annealing treatment. [ABSTRACT FROM AUTHOR]

In this paper, the microstructures of solder alloys were improved by adding trace elements of Ni to BiSbSn solder to enhance Bi-based solder alloys mechanical properties. The spreading areas, tensile strengths and shear strengths of the Bi-5Sb-8Sn-xNi solders with various Ni contents were characterised. The results revealed that after Ni was added to the BiSbSn solder, two new phases occurred: Ni3Sn4 and NiSb2. When the Ni content was 1%, the solder tensile strength was at the highest. When the Ni content was less than 3%, the shear strength increased as the Ni content increased. When the Ni content was more than 3%, the shear strength decreased gradually, primarily owing to the large amounts of impurities and pores introduced by the internal aggregation effect. In summary, when the Ni content was between 1 and 3%, the solders had the most-usable overall properties. [ABSTRACT FROM AUTHOR]

The effects of curing temperature on alkali activated slag cement (AAS) were investigated. The results indicate that the impact of the curing temperature is much more significant on the setting time of AAS than that of ordinary Portland cement. Curing at below normal temperature (∼7°C) greatly prolongs both the initial and final setting times, and also remarkably reduces the early age strength of AAS, whereas it will not lead to significant reduction in late age strengths. Scanning electron microscopy revealed significant difference in microstructures of AAS pastes cured for 28 days, and the compactness of the paste structure increases greatly with the increasing of the curing temperature. [ABSTRACT FROM AUTHOR]

The effect of cement/sand ratio of the original mortar, type of the activators and addition of slag powder on alkali activated recycled cement mortar powder (AARCMP) pastes were studied. The results show that the cement hydrates in recycled cement mortar can be activated by alkali to reconstruct new cementitious substances. Water glass is more effective as an activator than NaOH. Recycled cement mortar with higher original cement/sand ratio yields higher strengths, and addition of slag powder can remarkably increase the strengths of the materials. AARCMP paste with the 28 day flexural and compressive strengths of 7·5 and 45·4 MPa respectively was prepared by replacing 30% slag powder for the recycled mortar powder. Scanning electron microscopy revealed that there is a great difference between the microstructures of the hardened paste of AARCMP and that of ordinary Portland cement. [ABSTRACT FROM AUTHOR]

In this paper, a lattice Boltzmann method for modelling and simulation of droplet dynamics on both chemically heterogeneous and microstructured partial wetting surfaces with large liquid–gas density ratio is developed and reported. Applying the method, the effects of surface chemistry and topography on motions of liquid drops are studied and analysed numerically. The obtained steady contact angles are in good agreement with those of theoretical prediction. Moreover, based on the evolutions of phase distribution and flow fields obtained from the numerical calculation, the corresponding mechanisms of droplet dynamics on partial wetting surfaces including droplet spreading, breaking up, migration as well as dynamic apparent contact angle, etc. are discussed and analysed. [ABSTRACT FROM PUBLISHER]

A novel thermal spray material of Mo-Co-Cr-B with high durability in molten alloys has been developed to utilise for die casting parts and for galvanising bath parts. In the present paper, detonation gun (D gun) spray technique was used to deposit a Mo-Co-Cr-B alloy coating onto 316L stainless steel substrate, and the microstructures and mechanical properties of the coating system were studied using XRD, SEM, tensile test and Vickers microhardness. The results show that the microstructures of the coating consisted of ternary transition metal borides matrix CoMo2B2, CoMoB, as well as a little amount of binary borides, MoB and CrB. The ternary borides matrix contained both amorphous phase and nanocrystalline grains with a size of 60±35 nm. The bond strength of the coating decreases with increasing thickness of the as sprayed coatings. The anisotropy in the mechanical properties between the cross-section and plan section of the coatings is examined. Comparing the microhardness and bond strength of detonation sprayed Mo-Co-Cr-B coating with those of HVOF sprayed Mo-Co-Cr-B coating, it can be concluded that the detonation spray process has a better performance than HVOF spray process. [ABSTRACT FROM AUTHOR]

A (Ti,V)C/Fe composite was produced by self-propagating high temperature synthesis combined with powder metallurgy using Ti, Fe, FeV and carbon powder. The microstructure of the Fe–(Ti,V)C composite was studied by scanning electron microscopy and X-ray diffraction; with the help of differential thermal analysis, the reaction mechanism of the Fe–Ti–V–C system was discussed. The results show that the production of an iron matrix composite reinforced by (Ti,V)C particulates using the process is feasible. (Ti,V)C particles exhibit homogeneous distribution in the α-Fe matrix. The reaction mechanism is as follows: first, allotropic change Feα→Feγ and the reaction FeV+C→Fe+VC at 765·7°C; second, formation of the compound Fe2Ti at 1058·5°C because of the eutectic reaction between Ti and Fe; third, reaction between carbon and melted Fe2Ti causing formation of TiC at 1140·4°C; finally, formation of (Ti,V)C due to the solubility between TiC and VC. [ABSTRACT FROM AUTHOR]

Type I clathrate bulk materials Ba8Sb2Ga14Ge30 were prepared by the melt spinning (MS) technique combined with the spark plasma sintering (SPS) method. The microstructure and thermoelectric transport properties of the compounds were investigated. The results show that the grain size decreases greatly compared with materials obtained by the traditional melting and SPS method. The electrical conductivity increases greatly and the lattice thermal conductivity decreases significantly with increasing roller linear speed. The maximum thermoelectric dimensionless figure of merit ZT of 1.05 is obtained at 950 K for the sample prepared by melt spinning with a roller linear speed of 40 m/s. [ABSTRACT FROM AUTHOR]

The atomic force microscopy (AFM)-based mechanical nanoscratching method is employed to be integrated with self-assembly process on the surface of silicon (111) forming a novel fabricating approach: An AFM diamond tip is used to scratch the sample surface, forming complex structures with dimensions of several microns. Then the same sample is immersed into the hexadecane solution and heated to 200 °C for about 2 h. Finally, self-assembly monolayer is formed on all sample surfaces except the scratched area. Results of x-ray photoelectron spectroscopy analysis verify the formation of monolayer on the silicon surface. Mechanical properties of the sample such as friction and adhesive behaviours are studied by AFM. Results show that the scratched silicon surface has a larger friction force and adhesion force than the self-assembly monolayer area. [ABSTRACT FROM AUTHOR]

High-aspect ratio (HAR) silicon molds formed with deep-reactive ion etching (DRIE) technique are difficult to use as masters for replication, especially for replication of high-aspect ratio microstructures. Microstructures in silicon molds made by DRIE have high surface energy and wavy vertical side walls, both of which make demolding difficult. In the research reported here, microstructured silicon master molds were made with the DRIE technique; the mold microstructures were "trenches" with maximum depth and width of 146 µm and 9.8 µm, respectively. Silicone rubber replicas could not be successfully demolded from such a high aspect ratio (15) silicon master without further surface modification. A second similarly etched mold was plasma treated with C4F8 for 120 seconds after etching (postpassivated). This treatment was found to be successful; five faithful replicas in silicone rubber were successfully demolded from the postpassivated mold whereas the replica mold broke during demolding from the unpostpassivated master, leaving the master mold microstructure filled with silicone rubber. At higher aspect ratio of 18, the silicon mold had to be plasma treated with C4F8 for at least 400 s before five replicas could be demolded successfully. Post-passivation with C4F8 was found to reduce the root mean square sidewall roughness of the silicon master mold trenches by about halves. The nanotribology of the silicon surface was studied with atomic force microscopy. The friction coefficient of the silicon surface was found to be reduced six-fold by the postpassivation technique. XPS analyzes showed that when post-passivation timing was increased, concentration of C-F increased while that of C-CF decreased and the thickness of the fluorinated coating increased. These results show that postpassivation of silicon microstructures made by DRIE can be used to fabricate much higher aspect ratio molds that has heretofore been considered possible using this substrate material and fabrication technique. [ABSTRACT FROM AUTHOR]

Examines the effect of oxygen on interface microstructure evolution in cadmium sulfide\cadmium tellurium (CdS\CdTe) solar cells. Systemic layer characterization at various stages during heterojunction growth; Results of auger electron spectroscopy and transmission electron microscopy of the Cds\CdTe interface.

We have demonstrated the effect of gradients in phase composition and microstructure of p-type CeFe4Sb12 melt-spun ribbons on Seebeck coefficient by using a thermoelectric (TE) screening tool in conjunction with x-ray diffraction. The spatial Seebeck coefficient variation was found to correlate with the changes in the phase composition and microstructure. The observed gradient was the result of a postannealing effect caused by the thermal lag between the contact surface with the roller and the free surface. Our results illustrate the application of our screening tool to the three-dimensional variation in Seebeck coefficient in a model TE material. [ABSTRACT FROM AUTHOR]

In most Cu(In,Ga)Se[sub 2] thin films used for solar cells, there usually exist interfaces lying about 0.1 to 0.2 µm below surfaces. We report on convergent-beam electron diffraction and energy-dispersive x-ray spectroscopy study of the microstructure and chemical composition of the surface region in Cu(In,Ga)Se[sub 2] thin films. We find that the surface region and the bulk are structurally similar, with no ordered defect chalcopyrite structure observed. However, their composition is slightly different, indicating that they can have different point defect physics. Our results suggest that the subinterfaces and the bulk absorber may form homojunctions. [ABSTRACT FROM AUTHOR]

Abstract Lead‐free polycrystalline manganese telluride holds great potential in the development of waste heat recovery due to its fascinating physical properties. However, the poor thermoelectric (TE) performance in the p‐type MnTe alloys always results from their inferior carrier concentration, leading to low power factor and high thermal conductivity which restrict the overall thermoelectric performance. In this work, the problem is solved by decoupling its electrical and thermal transports through the hole donor Ge‐deficiency in MnTe + x mol.% GeTe (0 ≤ x ≤ 4) compounds. Intrinsically, extra GeTe in MnTe + x mol.% GeTe compound offers free charge carriers due to a narrow bandgap comparatively, realizing not only a full assessment of stimulated electrical performance but also an enhanced power factor. Moreover, benefiting from the nano‐precipitates and tweed microstructures, the lattice thermal conductivity effectively reduces due to the intensive phonon scattering accordingly. Ultimately, a maximum ZT of ≈1.2 at 873 K in the 3 mol.% GeTe doped MnTe sample is realized.

Abstract: Proton Beam Writing (PBW) is a direct write lithographic technique that has recently been applied to the fabrication of three dimensional metamaterials. In this work, we show that the unique capabilities of PBW, namely the ability to fabricate arrays of high resolution, high aspect ratio microstructures in polymer or replicated into metal, is well suited to metamaterials research. We have also developed a novel method for selectively electroless plating silver directly onto polymer structures that were fabricated using PBW. This method opens up new avenues for utilizing PBW for making metamaterials and other sub-wavelength metallic structures. Several potential applications of three dimensional metamaterials fabricated using PBW are discussed, including sensing and negative refractive index materials. [Copyright &y& Elsevier]

• The temperature and the size of the molten is affected by the heat accumulation. • The center of the molten pool shifts slightly toward back of the laser beam. • The simulated and experimental morphology in repaired area shows a good agreement. • The relationships among the thermal cycle, the grain size and the micro-hardness. 316L stainless steel plate with a trapezoidal groove was repaired by laser metal deposition (LMD) with 316L stainless steel powder. Finite element method (FEM) is adopted to predict the thermal behavior in the molten pool during the LMD. There is an overlapping between the adjacent tracks and adjacent layers during the LMD, forming a three dimensional structure. The influence of the second track in the first layer and the first track in the second layer on the first track in the first layer was investigated by the simulation process and experimental method. The numerical results indicated that the maximum temperature and the dimensions of the molten pool at the second track in the first layer and the first track in the second layer are larger than those at the first track in the first layer. The temperature of the first track in the first layer increases after the deposition of the second track in the first layer and the first track in the second layer. The microstructure evolution of the first track in the first layer was examined by the optical microscope (OM) and scanning electron microscope (SEM). The experimental results show that the thermal cycle caused by adjacent tracks brings about a significant effect on the microstructure and micro-hardness of the first track in the first layer. [ABSTRACT FROM AUTHOR]

The microstructure of a Ti-8Mo-6Fe ternary alloy with ultrafine grains was systematically studied with Tecnai-G2 F20 field transmission electron microscope and JEMS 2010 transmission electron microscope. A new Ti phase with face-centered-cubic (Fm-3m) structure was discovered. The morphology of these FCC Ti phases was elliptical, and they were widely distributed at interfaces between the polygonal BCC TiMoFe phases. The size of the FCC Ti phases was concentrated in the range of 200–450 nm. The lattice constant of FCC Ti phase was 0.431 nm. Simulated high-resolution images of FCC Ti and compounds of FCC TiC, TiN and TiO with different thicknesses and different defocus amounts were carried out to prove that the FCC structure in Ti-8Mo-6Fe alloy was indeed FCC Ti but not FCC TiC, TiN and TiO. First principle calculations revealed the metallic properties and stability of FCC Ti. All alloy elements of Mo and Fe were in the polygonal BCC TiMoFe phases. The semicircular arc periodic strips formed by electron diffuse scattering were present on the selected area electron diffraction (SAED) patterns of the BCC TiMoFe phase, which may come from the ordered domain of Mo and Fe or local ordering by Mo, Fe and Ti. [ABSTRACT FROM AUTHOR]

Abstract: The effects of the annealing temperature on the microstructure and the corrosion behavior of duplex stainless steel 2507 were investigated by means of magnetic force microscopy (MFM), scanning Kelvin probe force microscopy (SKPFM), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The SEM results indicated that the volume fraction of the austenite phase decreased with the increased annealing temperature. SKPFM/MFM measurements conducted in air at the room temperature and an ambient relative humidity of about 25% showed a higher Volta potential of the paramagnetic austenite than that of the ferromagnetic ferrite. The in situ AFM observation in a hydrochloric acid solution provided solid evidence that corrosion preferentially occurred in the ferrite phase. The sample annealed at 1100°C exhibited a greater Volta potential difference between the ferrite and austenite and a higher corrosion rate in the ferrite, while that annealed at 1150°C had a smaller Volta potential difference and a lower corrosion rate. The relative nobility and microstructure change of two phases, as well as their corrosion behavior, can be explained by the effect of the composition of alloying elements. [Copyright &y& Elsevier]

Abstract: The aim of the work was to study the properties of the bacterial cellulose membrane (BCM) and the feasibility of using it as a new, environmentally friendly support carrier for yeast cell immobilization. It was observed that the morphology of BCM varied with different cultivation methods and the scanning electron microscopy (SEM) images confirmed that the yeast cells were entrapped in the porous network of BCM obtained from the static culture and stabilized by the cross-linked fibrils. Particularly, the research confirmed the effectiveness of yeast immobilization in BCM reflected by the high yield of alcohol (9.7% v/v, a 21.25% increase of those using free cells) and the high stability. The specific rate of ethanol production by the immobilized cells in BCM was 2.1gg−1 h−1, 31.3% greater than that of the suspended cells. Results implied that applying BCM as the support carrier had little adverse effects on cell viability and proliferation. Instead, it facilitated the product leakage and nutrients transportation through the porous network. [Copyright &y& Elsevier]