Loss in coherency and coarsening behavior of Cr precipitates in Cu-Ag-Cr alloy

The coarsening behavior of Cr precipitates in Cu-0.1Ag-0.5Cr alloy was investigated, and the effects of aging processes on the microstructure and properties were discussed. The results show that the radius for coherent/semi-coherent transition of the Cr precipitates is determined from TEM micrographs as 1545nm. The calculated value of critical radius for a particle begining to lose coherency is about 12.5nm. The coherent (r<15nm) precipitates are found to coarsen and become semi-coherent during the passage of low-angle boundaries during recovery. The passage of high-angle boundaries through semi-coherent precipitates during recrystallization occurs by migration of the particle, resulting in the precipitates maintaining semi-coherent with the new grain.

Improved thermoelectric performance in p-type Bi_(0.48)Sb_(1.52)Te_3 bulk material by adding MnSb_2Se_4

Bismuth telluride（Bi2Te3） based alloys, such as p-type Bi（0.5）Sb（1.5）Te3, have been leading candidates for near room temperature thermoelectric applications. In this study, Bi（0.48）Sb（1.52）Te3 bulk materials with MnSb2Se4 were prepared using high-energy ball milling and spark plasma sintering（SPS） process. The addition of MnSb2Se4 to Bi（0.48）Sb（1.52）Te3 increased the hole concentration while slightly decreasing the Seebeck coefficient, thus optimising the electrical transport properties of the bulk material. In addition, the second phases of MnSb2Se4 and Bi（0.48）Sb（1.52）Te3 were observed in the Bi（0.48）Sb（1.52）Te3 matrix. The nanoparticles in the semi-coherent second phase of MnSb2Se4 behaved as scattering centres for phonons,yielding a reduction in the lattice thermal conductivity. Substantial enhancement of the figure of merit, ZT, has been achieved for Bi（0.48）Sb（1.52）Te3 by adding an Mn（0.8）Cu（0.2）Sb2Se4（2mol%） sample, for a wide range of temperatures, with a peak value of 1.43 at 375 K, corresponding to -40% improvement over its Bi（0.48）Sb（1.52）Te3 counterpart. Such enhancement of the thermoelectric（TE） performance of p-type Bi2Te3 based materials is believed to be advantageous for practical applications.

Effects of UV-, Visible-, Near-Infrared Beams in Three Therapy Resistance Case Studies of Fungal Skin infections

Fungal and bacterial diseases, directly infecting various parts of body, have received much attention in recent years. Bacterial infections, such as Tinea Pedis, Pityriasis versicolor and Mycetoma can secondarily occur in superficial fungal damaged skin. They often occur in immune compromised individuals including diabetics and patients with peripheral arterial diseases. Mycetoma infections can travel through the bloodstream affecting different organs. In this paper, we investigate the photo-inactivation of the pathogens causing Tinea Pedis, Pityriasis versicolor, and Mycetoma infections in three therapy resistant patients without photosensitizing drugs. We have used a combination of visible to near-infrared (VIS/NIR) laser beams in association with blue (B), red (R) and ultra-violet (UV) light emitted diodes (LEDs) with incident doses of 0.63 - 21.43 J/cm2. These beams have minimum side effects on the normal part of the skin. According to the physicians’ assessments, all case study patients achieved an observable progress such as decreases in inflammatory lesions, rapid process of wound healing and scars improvements. Side effects such as inflammation, crusting, or hypopigmentation were not observed. The presented irradiation protocol may be a valuable complementary treatment for patients suffering from fungal and bacterial skin infections.

Interface Design Strategy for GNS/AZ91 Composites with Semi-Coherent Structure

The interfacial structure plays an important role in the mechanical properties of magnesium matrix composite(MMCs)reinforced with graphene nanosheet(GNS)due to their poor wettability with the Mg matrix.An interface design strategy was proposed to form the semi-coherent interfacial structure with superior bonding strength.The lattice mismatch and interfacial bonding strength between Mg/rare earth oxide/carbon were utilized as key characteristics to evaluate the interfacial structure.Lanthanum oxide(La2O3)was selected as the intermediate candidate due to its low lattice mismatch and high interfacial bonding strength.To identify the interfacial structure of Mg/La2O3/graphene,first-principles calculations were conducted to calculate the ideal work of separation and electronic structure of the interfaces.Results demonstrated the presence of strong ionic and covalent interactions at the interface,which theoretically verified the strong interfacial bonding strength among Mg/La2O3/graphene interfaces.To experimentally validate the interface strength,MMCs with the interface structure of Mg/La2O3/GNS were developed.The formation of in-situ La2O3 led to the successful attainment of semi-coherent structures between Mg/La2O3 and La2O3/GNS,resulting in high strength and good ductility of the composite.Overall,this work proposes a new approach to interface design in MMCs with an enhancement of mechanical properties.

Tailoring alloy-reaction-induced semi-coherent interface to guide sodium nucleation and growth for long-term anode-less sodium-metal batteries

Sodium metal batteries are emerging as promising energy storage technologies owing to their high-energy density and rich resources.However,the challenge of achieving continuous operation at high areal capacity hinders the application of this system.Here,a robust two-dimensional tin/sodium‒tin alloy interface was introduced onto an Al substrate as an anode via an industrial electroplating strategy.Unlike the widely accepted in situ formation of Na15Sn4 alloys,the formation of Na_(9)Sn_(4)alloys results in a semi-coherent interface with sodium due to low lattice mismatch(20.84%),which alleviates the lattice stress of sodium deposition and induces subsequent dense sodium deposition under high areal capacity.In addition,the strong interaction of Sn with anions allows more PF6−to preferentially participate in the interfacial solvation structure,thereby facilitating the formation of a thin(10 nm)NaF-rich solid electrolyte interface.Therefore,the substrate can withstand a high areal capacity of 5 mA h cm^(-2),exhibiting a high average Coulombic efficiency of 99.7%.The full battery exhibits long-term cycling performance(600 cycles)with a low decay rate of 0.0018%per cycle at 60 mA g^(-1).

Enhanced mechanical properties of giant magnetostrictive Tb-Dy-Fe alloy via constructing semi-coherent interface between matrix phase and ductile grain boundary phase

Giant magnetostrictive Tb-Dy-Fe alloys in the form of thin sheets or fine wires are required in precision micro-actuators and sensors.However,Tb-Dy-Fe alloys are too brittle to undergo machining and application.In the present work,we investigated the effects of diffusing the Dy_(36 )Cu_(64 )alloy into the grain boundary phases of the<110>-oriented Tb_(0.30) Dy_(0.70 )Fe_(1.95) alloy to modify the microstructural,mechanical,and magnetostrictive properties.Microstructural analysis revealed the introduction of Cu into the grain boundary phase through the diffusion treatment,transforming the brittle rare earth(RE)-rich grain boundary phase into a ductile(Tb,Dy)Cu grain boundary phase and changing the non-coherent interface to a semi-coherent one between the(Tb,Dy)Fe_(2) matrix phase and the grain boundary phase without affecting the microstructure of the matrix phase.The as-diffused Tb_(0.30 )Dy_(0.70) Fe_(1.95) alloy exhibited significantly improved mechanical properties,with its tensile strength,bending strength,and fracture toughness at room temperature increasing to 44.6 MPa,106.8 MPa,and 2.36 MPa m^(1/2),respectively,which were 2,2.4,and 1.5 times those of the non-diffused sample.This was attributed to the formation of ductile(Tb,Dy)Cu grain boundary phase and semi-coherent interfaces.Furthermore,the magnetostrictive strain of the as-diffused Tb_(0.30) Dy_(0.70) Fe_(1.95) alloy reached 1448 ppm,suggesting that there was minimal impact on the magnetostrictive properties,due to the small influence of grain boundary diffusion on the matrix phase.

In situ TiN-reinforced CoCr2FeNiTi(0.5) high-entropy alloy composite coating fabricated by laser cladding

The fcc structural CoCr2 FeNiTi(0.5) high-entropy alloy(HEA) composite coating with TiN particles reinforced was acquired by laser cladding on the commercial904 L stainless steels.The results show that phase structure is mainly composed of fcc solid solution and TiN phases.The coating exhibits excellent structural stability below850℃.The microstructure consists of irregular dendrite and TiN particles.Transmission electron microscopy(TEM) results reveal that the close-packed plane of fcc phase is(111) with interplanar spacing of ~ 0.208 nm.The interface between TiN and fcc matrix is semi-coherent.And the angle of boundary between dendrite and matrix is ~ 65°.The hardness and corrosion resistance of coating have much improvement compared with those of substrate.

Ultra-high strength Mg-Li alloy with B2 particles and spinodal decomposition zones

The bcc-structured Mg-Li alloy is currently the engineering metallic material with the lowest density,but it has not been widely used due to its low strength.In this paper,alloying Zn effectively improves the strength of the bcc-structured Mg-Li alloy.Due to the semi-coherent B2 structured nanoparticles,the compressive yield strength of the as-cast Mg-13Li-9Zn alloy reaches higher than 300 MPa.Due to the solid solution strengthening of Zn and the spinodal zone,the compressive yield strength of the as-quenched Mg-13Li-15Zn(LZ1315)alloy immediately increases to 400 MPa.In addition,the as-quenched LZ1315 alloy exhibits natural aging strengthening behavior.Due to the precipitation of B2 nanoparticles,the yield strength of the peak aged alloy is up to 495 MPa.

Nitride-reinforced HfNbTaTiV high-entropy alloy with excellent room and elevated-temperature mechanical properties

Nitride-reinforced(HfNbTaTiV)_(90)N_(10) high-entropy alloy aiming at high-temperature applications is de-signed in this paper.Abundant FCC nitride phases are formed in situ in theBCC matrix by arc melt-ing technique,without complex deformation or heat treatment.The(HfNbTaTiV)_(90)N_(10) alloy exhibits a remarkable yield strength of 2716 MPa and ultimate compressive strength of 2833 MPa with a plas-tic strain of 10%at room temperature.Besides,the alloy remains a high yield strength of 279 MPa at 1400℃.The nitride phases play an essential role in maintaining the excellent strength-ductility com-bination at room temperature and enhancing the high-temperature softening resistance.Alternating BCC and FCC phases possess the semi-coherent interface,which not only strengthens the BCC matrix but also promotes the compatible deformation of the duplex microstructure.The lattice coherency structure of the semi-coherent interface is conducive to the slip transfer of partial dislocations through the interface,which facilitates the accommodation of plastic deformation.The cross-slip of the screw dislocations ef-fectively eliminates stress concentration and leads to good ductility of the dual-phase alloy.The results demonstrate that the nitride phases achieve coordinate deformation with the matrix without deteriorat-ing the ductility of the(HfNbTaTiV)_(90)N_(10) alloy.

Superheating and melting behaviors of Ag clusters with Ni coating studied by molecular dynamics and experiments

Using molecular dynamics with embedded-atom-type interatomicpotentials, we simulated the melting behavior of a spherical Ag3055 cluster coated with Ni. The semi-coherent Ag/Ni interface formed at low temperatures acts as an effective barrier against the surface melting and leads to a substantial superheating of the Ag cluster. The melting point was found to be about 100 K above the equilibrium melting point of the bulk Ag crystal (1230 K±15 K) and about 290 K above that (1040 K) of the free Ag3055 cluster. A superheating of 70 K was observed in the high-temperature differential scanning calorimetry measurement for Ag particles with a mean size of 30 nm embedded in Ni matrix prepared by means of melt-spinning. Melting is initiated locally at the defective interfacial area and then propagates inwards, suggesting a heterogeneously nucleated melting event at the Ag/Ni interface.