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[Display omitted] • Cu-Nb composite diffused metal interlayer was first applied to TC4 and 4J36 electron beam welding. • The use of Cu-Nb interlayer produces solid solutions in the two weld melting zones. • The use of Cu-Nb interlayer improves the quality of welded joint between TC4 and 4J36. • The formation mechanism of 4J36/Cu-Nb/TC4 bonded joints was studied. Electron beam welding of 4J36 invar alloy and TC4 titanium alloy was carried out with Cu-Nb composite diffused metal interlayer. The results showed that the depth to width ratio and the tensile strength of welded joints increased with the increase of electron beam current. Under the designed process parameters, two melting zones (MZ) in welded joints formed solid solutions (ss), the welded joint tensile strength reached maximum value of 244.1 MPa, and the fracture location was mainly located at 4J36/Cu interface. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to investigate the microstructure and properties of Cu-W alloys induced by high-current pulsed electron beam (HCPEB) irradiation. The microstructural observation shows that craters were formed after 5 pulses of HCPEB irradiation. With the increasing numbers of pulses, these craters were further fused and eliminated, which results in an excellent surface finishing. In addition, the composition of melted layer was homogenized because of the inter-diffusion between Cu and W atoms. During the process of HCPEB irradiation, several modifications were formed, including Cu (W) solid solution, ultrafine grains, amorphous phase, and long-period superlattice phase, which significantly increased the microhardness of the surface. The results of sliding wear tests indicate that the HCPEB irradiated samples exhibited better properties as compared to that of the initial one, which was attributed to the ultrafine W particles embedded in the Cu matrix. [ABSTRACT FROM AUTHOR]

Electron beam welding (EBW) was applied to 20 mm thick marine high-strength titanium alloy Ti6321 with different heat input conditions of the same line energy, and microstructure, microhardness and tensile properties of the defect-free welded joints were examined. The results show that for small heat input (SHI) weld metal, martensite α′ phase was wide and intertwined and the residual β was relatively high. For large heat input (LHI), martensite α′ was relative small. Microstructure of the HAZ is inhomogeneous. For SHI, β phase collected in fusion line, and the heat affected zone of SHI had more residual β phase than that of LHI. XRD results indicate that the weld metal of LHI nearly consists of α′ martensitic phase but small quantity of β phase. However, the weld metal of SHI exists α′martensitic phase, β phase and some α phase. Microhardness values in the centre of weld metal of SHI decreases greatly because of α phase. While hardness of LHI weld metal is consistent. The fracture locations of LHI EBW joint specimens are in base metal, and the UTS of the joints reach 935 MPa. The fracture locations of SHI EBW joint specimens are in weld metal, and the UTS of the joints reach about 905 MPa. [ABSTRACT FROM AUTHOR]

High current pulsed electron beam (HCPEB) technology was applied to irradiate the surface of mono-crystalline Ge wafers (Ge (100) and Ge (111)) with different orientations, and the microstructure and properties of the irradiated surface were analyzed in detail. The results show that after HCPEB irradiation, numerous molten pits and local microcracks were produced on the surface of mono-crystalline Ge, and the pit density decreased with the increase of irradiation pulses. TEM observations indicated that after irradiation, the defects are mainly vacancy group defects and dislocation rings, and Ge nanocrystals with uniform size distribution are produced. HCPEB irradiation also formed self-assembled nanostructures on the surface of Ge. Cross section TEM indicated that the 250 nm deep defect channels were under the quantum dots, which confirms the formation mechanism of self-assembled nanostructures. The photoluminescence results indicated that the irradiated mono-crystalline Ge still has blue emission properties, and the luminescence mechanism is the quantum confinement effect of Ge nanocrystals embedded in slightly oxidized or nitrided amorphous structures. • HCPEB irradiation can induce the proliferation of crystal defects and the formation of neatly arranged microcrack. • HCPEB irradiation induced numerous supersaturated vacancy defects in mono-crystalline Ge. • HCPEB irradiation induced the formation of nanocrystals on the Ge surface. • HCPEB irradiation induced the formation of self-assembled nanostructures on Ge surface. • After HCPEB irradiation, the blue light emission phenomenon of photoluminescence appeared in mono-crystalline Ge. [ABSTRACT FROM AUTHOR]

[Display omitted] • The cryogenic treatment was first applied to TC4/316L diffusion welded joint. • The effect of cryogenic treatment on microstructure of base metal TC4 and 316L was investigated. • The cryogenic treatment improves the quality of dissimilar joint between titanium alloy and stainless steel. • The bonding mechanism of joints and the influence mechanism of cryogenic treatment were analyzed. The diffusion welded joints of 316L/TC4 with Nb/Cu metal interlayer were subjected to cryogenic treatment. After cryogenic treatment, the strength of joints increased with the increase of soaking time. The strength of joints decreased with the increase of the cycle impact times. The average tensile strength of as-welded joints (AW) was 236.7 MPa, and the cryogenic treated samples for 24 h reached the best (280 MPa). The bonding mechanism of TC4/Nb/Cu/316L vacuum diffusion bonding joints and the influence mechanism of cryogenic treatment were analyzed. [ABSTRACT FROM AUTHOR]

Eyelid tarsus is a fibrocartilagenous extracellular matrix around meibomian glands providing structural support to eyelids and play important roles in the integrity of the ocular surface. There are no previous studies investigating the relationship between micro-structure and function of eyelid tarsus. To investigate the structure of extracellular matrix and the biomechanical properties of tarsus, rabbit tarsus were stained with hematoxylin and eosin (H&E), MASSON and Verhoeff's Van Gieson (EVG), distribution of collagen and elastin fibers in tarsus extracellular matrix were analyzed with scanning electron microscopy. Tarsus strips were collected and went through uniaxial tensile test with an Instron Universal Testing Machine. Data from 15 tarsus samples were included in the study. The initial tensile modulus was 2.554 ± 1.453 Mpa, and the final tensile modulus was 23.554 ± 3.657 Mpa, with an extensibility of 35.47 ± 7.46%. Collagen fibers formed peripheral layers of lamellae around meibomian glands, while the elastin fibres were organized in a parallel arrangement in horizontal and sagittal section, and in a crossed arrangement around meibomian glands. After tensile test, elastin fibres were stretched and arranged perpendicular to the direction of the collagen fibril lamellae. The findings of this study suggest that the extracellular matrix structure formed by collagen-elastin network contributes to a nonlinear mechanical characteristic of eyelid tarsus. [ABSTRACT FROM AUTHOR]

In this study, CoCrFeNiAl x (x = 0.1, 0.5, 1) high-entropy alloys (HEAs) are prepared using vacuum arc melting. In order to improve the surface properties of CoCrFeNiAl x HEAs, their microstructure is manipulated by laser surface remelting (LSM). The microstructure, the mechanical properties, and the corrosion resistance of the HEAs before and after LSM are studied systematically. The microstructural analysis reveals that the LSM-samples contained either a single FCC phase (CoCrFeNiAl 0.1 and CoCrFeNiAl 0.5) or a mixture of BCC + B2 phases (CoCrFeNiAl 1) with refined grains. Moreover, BCC precipitates and a spherical nano-dispersed phase (B2) are detected in the surface layer of CoCrFeNiAl 0.5 and CoCrFeNiAl 1 , respectively. The mechanical properties of CoCrFeNiAl x alloys are found to be significantly enhanced after LSM, which is mainly ascribed to the generation of the BCC phase, dislocation reinforcement and grain-strengthening as well as precipitation hardening. The electrochemical measurements confirm that all samples (after LSM) have a positive potential and a lower current density in 3.5 wt% NaCl solution compared to the untreated sample. The results indicate that LSM can help homogenize the structure and improve the properties of CoCrFeNiAl x HEAs. [Display omitted] • LSM treatment was conducted on the surface of as-cast CoCrFeNiAlx (x = 0.1,0.5,1) HEAs and the grains of each component were refined obviously. • A 365.2–1200 μm thick remelted layer was formed. • After LSM, abundant dislocation structures appeared on the surface, and spherical nano dispersed B2 phase was found in Al 1. • Surface microhardness, wear and corrosion resistance were improved evidently. [ABSTRACT FROM AUTHOR]

[Display omitted] • The deep cryogenic treatment was first applied to TC4/4J36 diffusion welding joint. • The effects of soaking time and cycles on mechanical properties of joint were studied. • The deep cryogenic treatment improves the quality of dissimilar joint between titanium alloy and steel. • The influence mechanism of deep cryogenic treatment on joint was studied. The diffusion welded joints of 4J36/TC4 with Ni/Cu/V metal interlayer were subjected to deep cryogenic treatment. The results showed that the extension of soaking time could improve the mechanical properties of the joint. The sample soaked for 8 h had the best performance, and it possessed ultimate tensile strength of 357.9 MPa and elongation of 24.9%. All samples failed at Cu/Ni interface with a ductile fracture manner, indicating that the joint still had good performance at low temperature. [ABSTRACT FROM AUTHOR]

• The V/Cu/Ni interlayer was first applied to weld TC4 titanium alloy and 4J36 invar alloy. • The use of V/Cu/Ni interlayer produces solid solutions at all interfaces. • The use of V/Cu/Ni interlayer improves the quality of dissimilar joint between titanium alloy and steel. • The formation mechanism of 4J36/Ni/Cu/V/TC4 bonded joints was studied. Diffusion bonding of 4J36 invar alloy and TC4 titanium alloy was carried out by inserting Ni/Cu/V multi-layer metal interlayer. The results showed that temperature had a significant effect on microstructure and mechanical properties of welded joints. At 890 °C, the joint tensile strength reached maximum value of 249.3 MPa. Fe-Ni solid solution ((Fe,Ni)ss), Cu-Ni solid solution ((Cu,Ni)ss), V-Cu solid solution ((V,Cu)ss) and Ti-V solid solution ((Ti,V)ss) were produced at interfaces of 4J36/Ni, Ni/Cu, Cu/V and V/TC4, respectively, and fracture surfaces of all joints showed dimples of different sizes, which showed that the application of Ni/Cu/V interlayer was an effective method. [ABSTRACT FROM AUTHOR]

Laser remelting (LR) treatment was used to regulate the microstructure of AlCoCrFeNiTa x high-entropy alloys prepared by vacuum arc melting, and the microstructure and properties of the alloys before and after LR treatment were analyzed. The original AlCoCrFeNiTa x alloys have typical dendritic morphology and the addition of Ta element promoted the formation of a Laves phase, gradually changing the alloys from two phase (BCC + B2) to three phase (BCC + B2 + Laves phase). After LR treatment, the grains were significantly refined, elemental segregation was alleviated, and a dense remelting layer with a thickness of 1200–1600 µm was formed on the surface of the alloy. In addition, the hardness and wear resistance of the alloys were improved with increasing Ta content and LR treatment, mainly caused by the combined effects of solution strengthening, second phase strengthening and fine grain strengthening. At the same time, the corrosion resistance of the alloys before and after LR treatment in 3.5 wt% NaCl solution is significantly improved by a stable Ta 2 O 5 and TaO 2 passivation films and the formation of a dense uniform remelting layer. • Refractory element was added and LR treatment was conducted on the surface of AlCoCrFeNiTax high entropy alloy. • After LR treatment, elemental segregation on the alloy surface is alleviated and the alloy grains are refined. • A remelted layer of about 1200–1600 µm thickness was formed on the alloy surface after LR treatment. • The hardness and wear resistance of the alloys were improved with increasing Ta content and LR treatment. • The corrosion resistance of the alloys in 3.5 wt% NaCl solution is improved by passivation film and remelted layer. [ABSTRACT FROM AUTHOR]

In order to improve the properties of AlCoCrFeNiNb x (x = 0, 0.1, and 0.5) high-entropy alloys (HEAs), the microstructure of the AlCoCrFeNiNb x is regulated by laser remelting (LR). By testing the microstructure and properties of alloys before and after LR treatment，the results indicate that the original AlCoCrFeNiNb x alloys have typical dendritic morphology, and the addition of the Nb element promoted the formation of Laves phase. The grains were significantly refined after LR treatment, and the dense remelting layers with thicknesses ranging from 1200 μm to 1650 μm were formed on the surface of the alloys. In addition, the hardness and wear resistance of the alloys were improved with the increase of Nb content and LR treatment due to the combined effect of fine grain strengthening, solid solution strengthening, and the second phase strengthening. At the same time, the corrosion resistance of the alloys before and after LR treatment in 3.5 wt% NaCl solution was significantly improved by the stable Nb 2 O 5 passivation film for Nb 0 and Nb 1 alloys. • LR treatment was conducted on the surface of as-cast AlCoCrFeNiNb x (x = 0.1,0.5 and 1) high entropy alloys. • AlCoCrFeNiNb x alloys have typical dendritic morphology, and the addition of the Nb element promoted the formation of Laves phase. • The grains were significantly refined after LR treatment, and the dense remelting layers with thicknesses ranging from 1200 μm to 1650 μm were formed on the surface of the alloys. • The hardness and wear resistance of the alloys were improved with the increase of Nb content and LR treatment due to the combined effect of fine grain strengthening, solid solution strengthening, and the second phase strengthening. • The corrosion resistance of the alloys before and after LR treatment in 3.5 wt% NaCl solution was significantly improved by the stable Nb 2 O 5 passivation film for Nb 0 and Nb 1 alloys. [ABSTRACT FROM AUTHOR]

Ultrasonic vibration (UV) treatment has been successfully applied to improve the particles distribution of nano-sized SiC particles (SiC p ) reinforced Al-5Cu alloy matrix composites which were prepared by combined processes of dry high energy ball milling and squeeze casting. When UV treatment is applied, the distribution of nano-sized SiC p has been greatly improved. After UV for 1 min, large particles aggregates are broken up into small aggregates due to effects of cavitation and the acoustic streaming. After UV for 5 min, all the particles aggregates are dispersed and the particles are uniformly distributed in the composites. Compared with the Al-5Cu matrix alloy, the ultimate tensile strength, yield strength and elongation of the 1 wt% nano-sized SiC p /Al-5Cu composites treated by UV for 5 min are 270 MPa, 173 MPa and 13.3%, which are increased by 7.6%, 6.8% and 29%, respectively. The improvements of mechanical properties after UV are attributed to the uniform distribution of nano particles, grain refinement of aluminum matrix alloy and reduction of porosity in the composites. [ABSTRACT FROM AUTHOR]

A biomedical β titanium alloy (Ti–7Nb–10Mo) was designed and prepared by vacuum arc self-consumable melting. The ingot was forged and rolled to plates, followed by quenching and aging. Age-hardening behavior, microstructure evolution and its influence on mechanical properties of the alloy during aging were investigated, using X-ray diffraction, transmission electron microscopy, tensile and hardness measurements. The electrochemical behavior of the alloy was investigated in Ringer's solution. The microstructure of solution-treated (ST) alloy consists of the supersaturated solid solution β phase and the ω ath formed during athermal process. The ST alloy exhibits Young's modulus of 80 GPa, tensile strength of 774 MPa and elongation of 20%. The precipitation sequences during isothermal aging at different temperatures were determined as β + ω ath → β + ω iso (144 h) at T aging = 350–400 °C, β + ω ath → β + ω iso + α → β + α at T aging = 500 °C, and β + ω ath → β + α at T aging = 600–650 °C, where ω iso forms during isothermal process. The mechanical properties of the alloy can be tailored easily through controlling the phase transition during aging. Comparing with the conventional Ti-6Al-4 V alloy, the Ti–7Nb–10Mo alloy is more resistant to corrosion in Ringer's solution. Results show that the Ti–7Nb–10Mo alloy is promising for biomedical applications. [ABSTRACT FROM AUTHOR]

The influence of microstructure on creep behavior of Ti–5Al–5Mo–5V–1Fe–1Cr (TC18) alloy at 350–500 °C and tensile stress of 200–400 MPa was investigated by creep testing and transmission electron microscope (TEM). The creep mechanism was discussed by microstructure evolution. The results showed that, the alloy with lamellar structure showed better creep resistance than that of equiaxed structure. At 350–400 °C, the stress exponent n of samples with both structure was in the range of 1.2–1.9, the creep was controlled by a/3〈 11 2 ¯ 0 〉 dislocations gliding on { 10 1 ¯ 0 } prism plane, {0002} basal plane and { 10 1 ¯ 1 } pyramidal plane. The creep activation energy of samples with both structure increased from 119 to 364 kJ/mol, with the increase of tensile stress from 200 to 400 MPa. At 450 °C, the stress exponent n of samples with both structure was about 3.0. At 500 °C, n is 4.3–4.8 under lower tensile stress, and 8.2–8.5 under higher tensile stress. At 450 °C and 500 °C, there was a dramatical rise of total creep strain, the jogged dislocation glided on {0002} basal plane was dominated, and the creep was controlled by dislocation climb. [ABSTRACT FROM AUTHOR]

Recently, high-entropy alloys have drawn lots of attention due to their outstanding properties. In this paper, a promising new surface modification technique was acted on CoCrFeNiMo 0.2 high-entropy alloy to improve its mechanical and corrosion properties. CoCrFeNiMo 0.2 high-entropy alloys were synthesized via vacuum arc melting then, their surfaces were processed by high-current pulsed electron beam (HCPEB). Microstructure, microhardness, wear and corrosion resistance were studied systematically by means of X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Before and after HCPEB irradiation, CoCrFeNiMo 0.2 high-entropy alloy had a face-centered cubic (FCC) structure, and the surface of the irradiated samples revealed preferential orientation on the (111) and (200) planes. In addition, a compact and homogenization surface layer formed after irradiation. Also, high-amplitude stress caused high-density dislocations and stacking faults on the surface. After HCPEB irradiation, the properties of the samples were significantly improved, the maximum microhardness (392.9 HV) and lowest wear rate (0.92 × 10−4 mm3·N−1·m−1) was obtained after 35-pulsed irradiation. Furthermore, corrosion resistance was obviously enhanced after 25-pulsed irradiation. [Display omitted] • HCPEB irradiation was conducted on the surface of as-cast CrFeCoNiMo 0.2 high entropy alloy. • A 3-8 μm thick compact remelted layer was formed after irradiation and the equiaxed grains along with σ phase were refined with the increase of the pulses. • Abundant structure defects such as subcrystals, high-density dislocations, dislocation cells, and stacking faults were also formed due to thermal stress induced by irradiation, resulting in intense plastic deformation of the material surface. • Surface microhardness, tribological behavior and corrosion resistance were improved due to grain refinement and compositional homogenization. [ABSTRACT FROM AUTHOR]