Subjects -> METALLURGY (Total: 59 journals)
Showing 1 - 10 of 10 Journals sorted alphabetically
Acta Metallurgica Slovaca     Open Access   (Followers: 2)
Advanced Device Materials     Open Access   (Followers: 6)
American Journal of Fluid Dynamics     Open Access   (Followers: 44)
Archives of Metallurgy and Materials     Open Access   (Followers: 9)
Asian Journal of Materials Science     Open Access   (Followers: 4)
Canadian Metallurgical Quarterly     Hybrid Journal   (Followers: 21)
Complex Metals     Open Access   (Followers: 2)
Energy Materials : Materials Science and Engineering for Energy Systems     Hybrid Journal   (Followers: 24)
Graphene and 2D Materials     Open Access   (Followers: 6)
Handbook of Ferromagnetic Materials     Full-text available via subscription   (Followers: 1)
Handbook of Magnetic Materials     Full-text available via subscription   (Followers: 2)
High Temperature Materials and Processes     Open Access   (Followers: 6)
Indian Journal of Engineering and Materials Sciences (IJEMS)     Open Access   (Followers: 11)
International Journal of Metallurgy and Alloys     Full-text available via subscription   (Followers: 2)
International Journal of Metals     Open Access   (Followers: 7)
International Journal of Minerals, Metallurgy, and Materials     Hybrid Journal   (Followers: 12)
International Journal of Mining and Geo-Engineering     Open Access   (Followers: 4)
Ironmaking & Steelmaking     Hybrid Journal   (Followers: 5)
ISIJ International - Iron and Steel Institute of Japan     Full-text available via subscription   (Followers: 26)
Izvestiya Vuzov. Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Proceedings of Higher Schools. Powder Metallurgy аnd Functional Coatings)     Full-text available via subscription   (Followers: 2)
JOM Journal of the Minerals, Metals and Materials Society     Hybrid Journal   (Followers: 35)
Journal of Advanced Joining Processes     Open Access  
Journal of Central South University     Hybrid Journal   (Followers: 1)
Journal of Cluster Science     Hybrid Journal  
Journal of Heavy Metal Toxicity and Diseases     Open Access  
Journal of Iron and Steel Research International     Hybrid Journal   (Followers: 11)
Journal of Materials & Metallurgical Engineering     Full-text available via subscription   (Followers: 2)
Journal of Materials Processing Technology     Hybrid Journal   (Followers: 21)
Journal of Metallurgical Engineering     Open Access   (Followers: 4)
Journal of Sustainable Metallurgy     Hybrid Journal   (Followers: 3)
Materials Science and Metallurgy Engineering     Open Access   (Followers: 7)
Metal Finishing     Full-text available via subscription   (Followers: 20)
Metallurgical and Materials Engineering     Open Access   (Followers: 7)
Metallurgical and Materials Transactions A     Hybrid Journal   (Followers: 42)
Metallurgical and Materials Transactions B     Hybrid Journal   (Followers: 32)
Metallurgical and Materials Transactions E     Full-text available via subscription   (Followers: 2)
Metallurgical Research & Technology     Full-text available via subscription  
Metallurgical Research and Technology     Full-text available via subscription   (Followers: 8)
Metallurgy and Foundry Engineering     Open Access   (Followers: 3)
Mining, Metallurgy & Exploration     Hybrid Journal  
Powder Diffraction     Full-text available via subscription   (Followers: 1)
Powder Metallurgy     Hybrid Journal   (Followers: 35)
Powder Metallurgy and Metal Ceramics     Hybrid Journal   (Followers: 7)
Powder Metallurgy Progress     Open Access   (Followers: 5)
Practical Metallography     Full-text available via subscription   (Followers: 6)
Rare Metals     Hybrid Journal   (Followers: 3)
Revista de Metalurgia     Open Access  
Revista del Instituto de Investigación de la Facultad de Ingeniería Geológica, Minera, Metalurgica y Geográfica     Open Access  
Revista Remetallica     Open Access   (Followers: 1)
Russian Metallurgy (Metally)     Full-text available via subscription   (Followers: 4)
Science and Technology of Welding and Joining     Hybrid Journal   (Followers: 8)
Soldering & Surface Mount Technology     Hybrid Journal   (Followers: 2)
Steel Times lnternational     Partially Free   (Followers: 19)
Transactions of the IMF     Hybrid Journal   (Followers: 14)
Transactions of the Indian Institute of Metals     Hybrid Journal   (Followers: 5)
Tungsten     Hybrid Journal  
Universal Journal of Materials Science     Open Access   (Followers: 3)
Welding in the World     Hybrid Journal   (Followers: 8)
Welding International     Hybrid Journal   (Followers: 11)
Вісник Приазовського Державного Технічного Університету. Серія: Технічні науки     Open Access  
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Rare Metals
Journal Prestige (SJR): 0.454
Citation Impact (citeScore): 1
Number of Followers: 3  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1001-0521 - ISSN (Online) 1867-7185
Published by Springer-Verlag Homepage  [2656 journals]
  • Microstructures and properties of 6016 aluminum alloy with gradient
           composition
    • Abstract: Weight reduction plays an important role in reducing fuel and emissions, and the heat-treatable 6016 aluminum alloy exhibits excellent application prospect in automobile lightweight. In this paper, ingot with constant Mg/Si ratio and decreased Mg and Si contents was obtained. Both the microstructure and the texture of 6016 aluminum alloy plate designed with different alloy compositions at the top/bottom were systematically investigated by electron backscatter diffraction technology (EBSD) measurement, as well as the room-temperature mechanical properties at the different positions with composition gradient. The results indicate that as Mg and Si contents increase, the grain size decreases, improving the cube texture with recrystallization and weakening the S texture. The strength of 6016 aluminum alloy decreases with lower Mg and Si contents. Graphic abstract
      PubDate: 2021-08-01
       
  • Deposition and characterization for high-quality Ti–Ni–Cu thin films
           with higher Cu content
    • Abstract: In order to attain high-quality Ti–Ni–Cu film, the surface morphologies, chemical compositions and mechanical properties of Ti–Ni–Cu thin films prepared by direct current (DC) magnetron sputtering at various processes were characterized by scanning electron microscopy (SEM), X-ray diffractometer (XRD) and tensile tests. The type of substrates, Ar pressure and sputtering power had significant effects on the quality and chemical composition of Ti–Ni–Cu thin film. Compared with Si and SiO2 slides, it was easier to obtain freestanding films by adopting glass or piezoid slide as substrates. The Ti–Ni–Cu thin film deposited at lower pressure (0.10 Pa) had a better density. The surface was featured with porous structure in the Ti–Ni–Cu thin film prepared by higher Ar pressure of 0.36 Pa. In addition, both the tensile strength and strain of annealed Ti–Ni–Cu thin film continuously increased with Ar pressure decreasing. Higher density contributed to the superior mechanical properties. The deposition rate firstly increased and then decreased with Ar pressure and sputtering power increasing. The composition of deposited Ti–Ni–Cu film can be tailored by changing sputter power. The deposited Ti–Ni–Cu thin films at different processing parameters were in amorphous state. In short, the present study offered the important theoretical basis for the preparation of Ti–Ni–Cu thin film with higher quality and performance. Graphic abstract
      PubDate: 2021-08-01
       
  • Preparation of {200} crystal faced SnO 2 nanorods with extremely high gas
           sensitivity at lower temperature
    • Abstract: Demand for simple and effective gas sensing sensors is growing rapidly due to the growing threat of triethylamine (TEA). Semiconductor tin oxide (SnO2) is one of the most widely used sensing materials for metal oxide gas sensors. In recent years, a lot of binary ternary compound researches have been carried out. In this paper, five different SnO2 samples were synthesized by simple synthesis method to understand the internal relationship and obtain different gas sensing characteristics. Based on the low temperature nitrogen adsorption tests and the atomic arrangement model, it can be inferred that different exposed surfaces play a key role in TEA sensing properties. In addition, the TEA sensing activity relationship of SnO2 exposed crystal faces is proposed as listed: (200) > (101) > (110). Graphic abstract
      PubDate: 2021-08-01
       
  • Microstructure, mechanical properties and fracture behavior of a new WE43
           alloy
    • Abstract: The microstructures, mechanical properties and fracture behaviors of a new WE43 alloy (Mg–4Y–1.6Nd–2Sm–0.5Zr) were investigated. The microstructure of the as-cast alloy includes a Mg matrix, Mg41Sm5, Mg41Nd5 and Mg24Y5 eutectic phases, as well as β-phase. After an optimal solution treatment, the eutectic phases are almost completely dissolved; only a few spots of blocky Mg–Y compounds remain at grain boundaries. After an aging treatment, a large amount of β′-phases are dispersed and precipitated at the grain interior, which provides good comprehensive mechanical properties of the alloy, particularly in the under-aged state. The tensile strength is up to 290 MPa, the yield strength reaches 209 MPa, and the elongation is slightly improved. Furthermore, the fracture behaviors of the studied alloy in different states significantly differ. In addition, a comparison of mechanical properties of the new WE43, traditional WE43 and other modified WE43 alloys is presented.
      PubDate: 2021-08-01
       
  • Microstructure and mechanical properties of TiAl/Ni-based superalloy
           joints vacuum brazed with Ti–Zr–Fe–Cu–Ni–Co–Mo filler metal
    • Abstract: For the purpose of elevated temperature service and weight reduction in aerospace vehicle applications, a novel Ti–Zr–Fe–Cu–Ni–Co–Mo filler metal was employed to join TiAl to Ni-based superalloy (GH536). The effects of brazing temperature on interfacial microstructure and chemical composition of the joints were analyzed. The representative joint microstructure from TiAl substrate to GH536 substrate was primarily composed of four characteristic layers in order: B2; Al3NiTi2; AlNi2Ti containing Cr-rich (Cr, Ni, Fe)ss (subscript ss represents solid solution), Ni-rich (Ni, Cr, Fe)ss and TiNi3; Cr-rich (Cr, Ni, Fe)ss containing AlNi2Ti, Ni-rich (Ni, Cr, Fe)ss and TiNi3. Layer IV has the majority of the brazing seam, while Layer II was the thinnest. And the thickness of Layer II was not affected by brazing temperature. With the increase in brazing temperature in the range of 1110–1170 °C, both the shear strength and the thickness of brazing seam firstly increased and then decreased. The joint performance was jointly controlled by the thickness of brazing seam, the amounts of microcracks and intermetallic compounds formed in brazing seam. The maximum shear strength of 183 MPa at room temperature was obtained together with a peak thickness when the joint was brazed at 1150 °C for 10 min and the shear fracture mainly occurred in the thinnest Layer II Al3NiTi2. Graphic abstract
      PubDate: 2021-08-01
       
  • Microstructural evolution and numerical simulation of laser-welded Ti 2
           AlNb joints under different heat inputs
    • Abstract: The influence of heat input on the microstructural evolution of laser-welded Ti2AlNb joints was investigated in this study. The thermal cycles during welding process were analyzed by numerical simulation. In the heat affected zone (HAZ), the amount of α2 and O phases decreased with laser power increasing. During the heating period, α2 → B2 and O → B2 transformations occurred, but the decomposition of the B2 phase into α2 and O phases was suppressed during the cooling period. The heat transfer in the HAZ generated more equiaxed B2 grains, fewer LAGBs and a weaker {001} \(<\!\!1{\bar1}0\!\!>\) texture due to recovery, recrystallization and grain growth. The phase composition of the fusion zone remained single with only the B2 phase with the increase in heat input, but the mode of grain growth transformed from cellular growth into cellular dendritic growth. A finite element model was established to simulate the thermal cycles during the welding process. Higher heat input induced higher peak temperature, leading to higher temperatures in the HAZ for longer periods of time, which was beneficial for the α2 → B2 and O → B2 transformations. The calculated cooling rates in both the HAZ and in the fusion zone were faster than the critical cooling rate for B2 → α2 and B2 → O transformations. Graphic abstract
      PubDate: 2021-08-01
       
  • Migration regularities of impurity aluminum and copper in purification of
           metal lanthanum by solid-state electrotransport
    • Abstract: In view of the previous studies on the migrations of impurity aluminum (Al) and copper (Cu) in purification of rare earth metal by solid-state electrotransport (SSE), there are still some questions about that which direction they migrate to and whether there are significant migrations or not. The metal lanthanum (La) was used as research object, and the effects of migration temperature and time on the distributions and migration regularities of impurity Al and Cu were investigated in the present study by increasing concentration of impurity Al and Cu in raw metal La. The impurity migration direction and removal difficulty were intuitively judged by the residual rate distribution curve of impurity. It is indicated that metal impurity Al and Cu in metal La at 800 °C with direct current are found to significantly migrate to anode and their residual rates near cathode decrease with the increase in migration temperature and prolongation of migration time. The relatively large vapor pressure of Al and Cu makes their residual rate distribution curves being low in middle and high in ends. When metal La was continuously purified for 100 h at 800 °C by SSE, the residual rates of impurity Al and Cu at 20 mm from cathode are 68.43% and 57.43%, respectively, showing that Cu is much easier to be removed than Al.
      PubDate: 2021-08-01
       
  • Microstructural evolution and aging behavior of
           Mg–4.5Y–2.5Nd–1.0Gd–0.5Zr alloys with different Zn additions
    • Abstract: Microstructures and mechanical properties of Mg–4.5Y–2.5Nd–1.0Gd–0.5Zr–xZn (x = 0, 0.5, 1.0, and 1.5; wt%) alloys under as-cast and peak-aged states were investigated in this work. The results indicate that the intermetallic phase components are closely dependent on Zn content. Under as-cast state, the dominant eutectic phase is Mg5RE in the alloys with 0 wt% and 0.5 wt% Zn additions while Mg5RE, 18R- and 14H-LPSO (long period stacking ordered) phases in the alloys with 1.0 wt% and 1.5 wt% Zn additions. After solution and peak-aging, the highest strength and hardness were obtained on the alloy with 0.5 wt% Zn addition. Transmission electron microscopy (TEM) characterizations revealed that there are denser and finer precipitates on basal (β′) and prismatic (γ″) planes, respectively. Therefore, the excellent mechanical performance of the alloy with 0.5 wt% Zn addition is mainly due to precipitation strengthening and grain boundary strengthening. Graphic abstract
      PubDate: 2021-08-01
       
  • A comparison between novel Gd 2 Zr 2 O 7 and Gd 2 Zr 2 O 7 /YSZ thermal
           barrier coatings fabricated by plasma spray-physical vapor deposition
    • Abstract: Spherical Gd2Zr2O7 hollow powders with a mean size of 8.8 μm were fabricated as feedstock for thermal barrier coatings (TBCs) by spray-drying. The single-ceramic-layer (SCL) Gd2Zr2O7 TBCs and double-ceramic-layer (DCL) Gd2Zr2O7/YSZ TBCs with quasi-columnar structure were successfully fabricated by plasma spray-physical vapor deposition (PS-PVD). Tensile and water-quenching tests were applied to evaluate TBCs performances. The results show that adhesion strength of SCL Gd2Zr2O7 TBCs and DCL Gd2Zr2O7/YSZ TBCs is 36.5 MPa and 15.4 MPa, respectively. The delamination of SCL Gd2Zr2O7 TBCs and DCL Gd2Zr2O7/YSZ TBCs in the tensile test takes place at the middle and bottom of Gd2Zr2O7 layer, respectively, due to relatively lower fracture toughness of Gd2Zr2O7 layer. After 40 cycles of water-quenching test, DCL Gd2Zr2O7/YSZ TBC surface keeps relatively intact, while SCL Gd2Zr2O7 TBC surface shows 20% visible destroyed regions, which demonstrates that DCL Gd2Zr2O7/YSZ TBCs have a better thermal shock resistance than SCL Gd2Zr2O7 TBCs. The cracks in the SCL system propagate near thermally grown oxide (TGO) due to thermal mismatch and TGO growing stress, while cracks in the DCL system propagate in the Gd2Zr2O7 layer due to its relatively lower fracture toughness.
      PubDate: 2021-08-01
       
  • Microstructure and mechanical properties of friction-stir-welded
           high-Mg-alloyed Al–Mg alloy plates at different rotating rates
    • Abstract: Hot-rolled high-Mg-alloyed Al–Mg alloy (Al–9.2Mg–0.8Mn–0.2Zr–0.15Ti, labeled as 5A12) plates were successfully friction stir welded at rotating rates ranging from 750 to 1500 r·min−1 at a constant welding speed of 50 mm·min−1. The joints were characterized by optical microscopy (OM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), electron-dispersive spectroscopy (EDS), and tensile testing. All the joints are volume defect-free and exhibit fine, equiaxed dynamic recrystallization (DRX) grains with high-angle grain boundaries (HAGBs) fractions of 88.6%–93.3% in the nugget zones (NZs). The DRX grain size and the second-phase particle size in the NZs have a parabolic relation with the rotating rate. Furthermore, among the joints tested, the joint prepared at 1000 r·min−1, which has the highest ultimate tensile strength ((478 ± 3) MPa) and the largest elongation to rupture (22.5% ± 1.4%)—approximately 87.5% and 145.2% those of the base metal, respectively, exhibits the smallest grain size of 2.93 μm, as well as the smallest particle size in the NZs. These excellent mechanical properties can be ascribed to the combined effects of the fine DRX grains with high fraction of HAGBs and the fine second-phase particles with a uniform distribution. Graphic abstract
      PubDate: 2021-08-01
       
  • Zr 55 Al 10 Ni 5 Cu 30 amorphous alloy film prepared by magnetron
           sputtering method
    • Abstract: In this work, amorphous Zr55Al10Ni5Cu30 alloy thin film was prepared on D36 steel substrate by magnetron sputtering method. The film was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), hardness tester and nano indentation. Corrosion behavior of the film was investigated in 3.5% NaCl aqueous solutions by an electrochemical method. At room temperature, the amorphous alloy film was formed completely after sputtering for 5 h. The surface morphology of the amorphous alloy film was uniform and smooth. Formation of the amorphous alloy film improved the microhardness and corrosion resistance of the D36 substrate. The amorphous alloy film (prepared at room temperature for 5 h) exhibited good adhesion strength with the substrate. The as-sputtered sample exhibited a crevice corrosion trend when the sputtering time was too short (1 h) or too long (10 h). Graphic abstract
      PubDate: 2021-08-01
       
  • Characteristics of oxide pegs in Ti- and Y-doped CoNiCrAl alloys at
           1150 °C
    • Abstract: Oxide pegging is a widely accepted mechanistic model explaining the reactive element effect on the improved adherence of scale. However, previous models for the oxide peg formation process have not considered the effects of more than one active element added into the alloy during the peg formation. This study proposes a new model of oxide peg formation and growth for the doping of two reactive elements in an alloy (the precipitated Y and solid solute Ti). Different amounts of Ti and Y were added to a CoNiCrAl alloy, and the characteristics of the resulting oxide pegs, such as their linear density, size, and forming process, are obtained by examining alloy samples subjected to an isothermal oxidation operation at a temperature of 1150 °C. It is found that the amount of Y determines the density of the oxide pegs, and Ti does not form a Ti-rich oxide core if a Y-rich oxide exists in the sample. In samples with the same Y content, the oxide pegs primarily grow in length, and with increased Ti content, they grow along the β-phase boundary and into the alloy. Based on these results, a three-step model for oxide peg formation and growth is conceived.
      PubDate: 2021-08-01
       
  • Evolution of microstructure and intervariant boundaries of α phase in
           electron beam melted and heat-treated Ti–6Al–4V alloy
    • Abstract: It is important to understand the correlation between grain morphology and intervariant boundaries of the α phase after heat treatment below β transus of the electron beam melted (EBMed) Ti–6Al–4V alloy. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) analysis have shown about 99% α phase and 1% β phase in the heat-treated samples when the temperature rises to 950 °C. Four distinct types of α grain morphology have been found: allotromorphous α, relatively coarse α plate, large precipitation α and granular α. A single peak of the intervariant boundary with the misorientation of 60°/ \(\left[ {11\bar{2}0} \right]\) associated with Burgers orientation relationship (OR) was found in the allotromorphous α colony. Multiple intervariant boundaries mixed with a fraction of general high-angle grain boundary (GHABs, not Burgers OR) were present in the relatively coarse α plate colony. Almost only low-angle grain boundaries (LABs) with the misorientation of < 5° were found in the large precipitation α grains. β phase tends to distribute around the boundaries of relatively coarse α plates. It suggests that different formation mechanisms are involved in the distinct types of α grain morphology.
      PubDate: 2021-08-01
       
  • Microstructure and mechanical properties of spark plasma-sintered La 2 O 3
           dispersion-strengthened W–Ni–Fe alloy
    • Abstract: An investigation of lanthanum oxide (La2O3) addition to tungsten heavy alloy (WHA) with a ternary composition of W–7Ni–3Fe was reported in this study. The mixed powders were sintered using spark plasma sintering (SPS) technique. La2O3 was added in increments of 0.25 wt%, 0.50 wt%, 0.75 wt% and 1.00 wt% to WHA, respectively. The sintered samples were characterized for microstructural evolution and mechanical properties. The influences of La2O3 addition on density, grain size, hardness, ultimate tensile strength (UTS) and ductility on W–7Ni–3Fe system were discussed in this study. The highest relative sintered density of 87.95% was obtained for 0.25 wt% La2O3 addition to W–7Ni–3Fe. The lowest grain size of 7.89 μm was observed for 1.00 wt% La2O3 addition. Similarly, the highest hardness and UTS of HV 533 and 1110 MPa, respectively, were also obtained for the same composition. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) of the samples revealed homogenous distribution of La2O3 in the alloy matrix. Fractography of the sintered alloy samples revealed W–W intergranular fracture.
      PubDate: 2021-08-01
       
  • A chitosan/amido-graphene oxide-based self-powered humidity sensor enabled
           by triboelectric effect
    • Abstract: In this work, amido-graphene oxide (GO-NH2) loaded chitosan (CTS) composite material (CTS/GO-NH2) that acts as both the triboelectric and sensing film was prepared on rotary fan-shaped triboelectric nanogenerator for humidity detection. Compared with the pristine CTS-based triboelectric humidity sensor (CTS-THS) and GO-NH2-THS, the CTS/GO-NH2-based humidity sensor exhibited higher humidity response and better linearity in the relative humidity (RH) range of 18.7%RH–91.5%RH. The above results can be explained by the massive exposed and less concealed hydrophilic functional groups of CTS with the help of the wrinkle structure of GO-NH2. Meanwhile, the CTS/GO-NH2-THS possessed good repeatability and acceptable hysteresis (~ 6.2%RH). Finally, a humidity sensing mechanism coupling triboelectric contact charging effect with electrons transfer principle under moisture environment was established to interpret the enhanced humidity sensing performance of the composite film-based THS. This work demonstrates that CTS/GO-NH2 composite film can be utilized to fabricate humidity sensors based on the triboelectric effect. Graphic
      PubDate: 2021-08-01
       
  • Tensile deformation behavior of coarse-grained Ti-55 titanium alloy with
           different hydrogen additions
    • Abstract: The effect of hydrogen addition on the deformation behavior of coarse-grained Ti-55 alloys (~ 20 μm) was studied by uniaxial tension tests at high temperature. The elongation of hydrogenated Ti-55 titanium alloy firstly increases and then decreases with hydrogen content increasing at 875 °C. The highest elongation of 243.8% is obtained in the hydrogenated alloy with 0.1 wt% H, and the peak stress reaches a minimum value of 29.0 MPa in the hydrogenated alloy with 0.3 wt% H. Compared with that of the unhydrogenated alloy, the elongation of the hydrogenated alloy with 0.1 wt% H increases by 41.3% and its peak stress decreases by 40.6% at 875 °C. Hydrogen addition can promote the transformation of β phase and the dislocation movement. Appropriate hydrogen content can evidently improve the deformation properties of coarse-grained Ti-55 titanium alloy. Graphic abstract
      PubDate: 2021-08-01
       
  • Mechanism of adding rhenium to improve hot corrosion resistance of
           nickel-based single-crystal superalloys
    • Abstract: Hot corrosion behavior in sulfate salt at 950 °C of Rene N5 single-crystal superalloys with 3 wt% rhenium (NSR) was investigated compared with that of nickel-based single-crystal superalloys without rhenium (NS). After 30-h corrosion, the surface of the NS superalloy is seriously corroded. Many holes and exfoliation appear on the surface. The NSR superalloys exhibit better hot corrosion resistance than the NS superalloys. After 30-h corrosion, a continuous and compact Al2O3 film is observed on its surface. The Al2O3 film with dense structure formed on the surface provides protection for the matrix. The characterization results show that Al is aggregated in the γ′ phase, while Re is aggregated in the γ phase during the formation of oxide scale. Considering that Re can inhibit the diffusion of Al in the nickel matrix, it is inferred that Re can inhibit the outward diffusion of Al and prevent the decrease of Al concentration in the γ′ phase. High concentration of Al hinders the decomposition of Al2O3 due to the reaction of acid and basic dissolution. Al2O3 keeps its structure intact and provides protection for the matrix.
      PubDate: 2021-08-01
       
  • Microstructure, mechanical properties and stretch formability of as-rolled
           Mg alloys with Zn and Er additions
    • Abstract: The magnesium alloy has a unique advantage in 3C fields due to its high specific strength and excellent electromagnetic shielding characteristic. However, it is difficult to deform homogeneously because of hexagonal close-packed structure. In the present work, the microstructure, mechanical properties and stretch formability of magnesium alloy sheets with different alloying elements were investigated. It was indicated that a trace addition of Zn or/and Er made a key role in modifying texture, activating shear bands formation and precipitating nanoscale second phases, respectively, which resulted in an obvious improvement in both stretch formability and mechanical properties. The results suggested that the Mg–0.5Zn–0.5Er alloy sheet exhibited higher tensile strength along the rolling direction, i.e., yield strength of 180 MPa and ultimate tensile strength of 201 MPa, accompanying with superior Erichsen value of 7.0 mm at room temperature. The good performances of the sheet were ascribed to weakening basal texture intensity, formation of shear bands and precipitation of nanoscale W-phase (Mg3Zn3Er2). Graphic abstract The microstructure, mechanical properties and stretch formability of magnesium alloy sheets with different alloying elements were investigated in the present investigation. It was indicated that a trace addition of Zn or/and Er made a key role in modifying texture (Fig. 1), activating shear bands formation and precipitating nanoscale secondary phases (Fig. 2), respectively, which resulted in an obvious improvement in both stretch formability and mechanical properties (Fig. 3).
      PubDate: 2021-08-01
       
  • Construction of high-performance magnetic sensor based on anisotropic
           magnetoresistance Ta/MgO/NiFe/MgO/Ta film
    • Abstract: The anisotropic magnetoresistance film is an important core material for developing the magnetic sensors. Here, Ta(5)/MgO(3)/NiFe(10)/MgO(3)/Ta(3) multilayers (in nanometer) were prepared by magnetron sputtering and further applied to construct a sensor element by combining with the Wheatstone bridge. The 1/f noise of the sensor element was greatly reduced by three orders of magnitude after annealing at 400 °C for 7200 s, which was mainly due to the significant microstructural changes during the annealing. However, when the sensor element was applied to detect the magnetic signal of a magnetic code disk with 512 N–S magnetic poles, the output voltage signal of the sensor displayed a large fluctuation of ± 0.05 V. In order to reduce the voltage fluctuation, a magnetic sensor chip by using a parallelly arranged multi-path Wheatstone bridges and auto-gain compensation structure was designed, and magnetic sensor elements and the high-performance computing drive module were prepared. The output voltage fluctuation of the magnetic sensor was reduced by about 90% and approached to ± 0.005 V. These findings provide an important basis for the practical application of NiFe-based magnetic sensing film materials. Graphic abstract
      PubDate: 2021-08-01
       
  • Preparation and properties of hot-deformed magnets processed from
           nanocrystalline/amorphous Nd–Fe–B powders
    • Abstract: The hot-deformed magnets processed from nanocrystalline/amorphous Nd–Fe–B powders were prepared under different hot-pressing temperatures (600–750 °C, at intervals of 25 °C) by the self-made hot-pressing equipment. The microstructure and magnetic properties of hot-deformed magnets prepared at different temperatures were also investigated. When the temperature is above 650 °C, the density of magnet reaches 7.5 g·cm−3. The optimum magnetic properties of magnetic induction intensity of Br = 1.3 T, optimum energy product of (BH)max = 282.5 kJ·m−3, intrinsic coercivity of Hcj = 1130.0 kA·m−1 of hot-deformed magnets are obtained at hot-pressing temperature of 650 °C. X-ray diffractometer pattern shows that the (00L) texture has been obtained. For the microstructural characteristic, on the one hand, the good magnetic performance is attributed to the fine platelet-like grains with an average length of 410–440 nm at the hot-pressing temperature range from 625 to 675 °C. On the other hand, the unaligned coarse grains are observed in all the samples. And the areal fraction of those is gradually increasing with the rise of the hot-pressing temperature, which tends to deteriorate the magnetic properties. The composition map shows the accumulation of Nd/Pr-rich phase in the coarse grains’ region.
      PubDate: 2021-08-01
       
 
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