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 Acta Metallurgica Sinica (English Letters)Journal Prestige (SJR): 0.576 Citation Impact (citeScore): 2Number of Followers: 7      Hybrid journal (It can contain Open Access articles) ISSN (Print) 1006-7191 - ISSN (Online) 2194-1289 Published by Springer-Verlag  [2350 journals]
• Young’s Modulus Enhancement and Measurement in CNT/Al Nanocomposites
• Authors: Zi-Yun Yu; Zhan-Qiu Tan; Gen-Lian Fan; Ren-Bang Lin; Ding-Bang Xiong; Qiang Guo; Yi-Shi Su; Zhi-Qiang Li; Di Zhang
Pages: 1121 - 1129
Abstract: Abstract Young’s modulus is a critical parameter for designing lightweight structure, but Al and its alloys only demonstrate a limited value of 70–72 GPa. The introduction of carbon nanotubes (CNTs) is an effective way to make Al and its alloys stiffer. However, little research attention has been paid to Young’s modulus of CNT/Al nanocomposites attributed to the uncertain measurement and unconvincing stiffening effect of CNTs. In this work, improved Young’s modulus of 82.4 ± 0.4 GPa has been achieved in 1.5 wt% CNT/Al nanocomposite fabricated by flake powder metallurgy, which was determined by resonance test and 13.5% higher than 72.6 ± 0.64 GPa of Al matrix. A comparative study and statistical analysis further revealed that Young’s modulus determined by tensile test was relatively imprecise (83.1 ± 4.0 GPa) due to the low-stress microplasticity or interface decohesion during tensile deformation of CNT/Al nanocomposite, while the value (98–100 GPa) was highly overestimated by nanoindentation due to the “pile-up” effect. This work shows an in-depth discussion on studying Young’s modulus of CNT/Al nanocomposites.
PubDate: 2018-11-01
DOI: 10.1007/s40195-018-0730-8
Issue No: Vol. 31, No. 11 (2018)

• Ni-Based Metallic Glass Composites Containing Cu-Rich Crystalline
Nanospheres
• Authors: Yao-Yao Xi; Jie He; Xiao-Jun Sun; Wang Li; Jiu-Zhou Zhao; Hong-Ri Hao; Ting Xiong
Pages: 1130 - 1136
Abstract: Abstract In this work, a quaternary Ni–Cu–Nb–Ta system has been designed to obtain composite microstructure with spherical crystalline Cu-rich particles embedded in amorphous Ni-rich matrix. The alloy samples were prepared by using single-roller melting-spinning method. The microstructure and thermal properties of the as-quenched alloy samples were characterized by X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and differential scanning calorimetry. It shows that the spherical crystalline Cu-rich particles are embedded in the amorphous Ni-rich matrix. The average size of the Cu-rich particles is strongly dependent upon the Cu content. The effect of the alloy composition on the behavior of liquid–liquid phase separation and microstructure evolution was discussed. The phase formation in the Ni-based metallic glass matrix composite was analyzed.
PubDate: 2018-11-01
DOI: 10.1007/s40195-018-0756-y
Issue No: Vol. 31, No. 11 (2018)

• Crevice Corrosion of Several Supper Stainless Steels in the Simulated
LT-MED Environment
• Authors: Chang-Gang Wang; Xiao-Fang Li; Jie Wei; Xin Wei; Fang Xue; Rong-Yao Ma; Jun-Hua Dong; Wei Ke
Pages: 1137 - 1147
Abstract: Abstract Susceptibility and morphological characteristics of crevice corrosion for SS316, SS904L, SS254sMo and SS2507 in the simulated low-temperature multi-effect distillation environment were investigated by cyclic polarization test, scanning electron microscope and laser microscope. The results show that the crevice corrosion resistance of four kinds of stainless steel is ranked as SS254sMo ≈ SS2507 > SS316 > SS904L. There are “cover” structures over the edge of active crevice corrosion regions of SS904L, SS254sMo and SS2507, but SS316 is an exception. Galvanic corrosion characteristics appeared in the crevice of duplex supper stainless steel SS2507.
PubDate: 2018-11-01
DOI: 10.1007/s40195-018-0728-2
Issue No: Vol. 31, No. 11 (2018)

• Evolution of the Corrosion Product Film and Its Effect on the
Erosion–Corrosion Behavior of Two Commercial 90Cu–10Ni Tubes in
Seawater
• Authors: Okpo O. Ekerenam; Ai-Li Ma; Yu-Gui Zheng; Si-Yu He; Peter C. Okafor
Pages: 1148 - 1170
Abstract: Abstract The composition and structural evolution of the corrosion product film of two commercial 90Cu–10Ni tubes, namely Tube A and Tube B, after being immersed in natural seawater for 1, 3, and 6 months were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, and its effect on the erosion–corrosion behavior of the tubes was determined through a rotating cylinder electrode system using various electrochemical techniques. For the freshly polished samples used as contrast samples, the flow velocity mainly enhanced the cathodic reaction at low flow velocities while both the anodic and the cathodic reactions were remarkably accelerated at higher flow velocities. The corrosion product films formed on the two commercial 90Cu–10Ni tubes after being immersed in seawater for up to 6 months are of a complex three-layer or multilayer structure. The structural evolution of the films is out of sync for the two tubes. A continuous residual substrate layer depleted of Ni was observed in the inner layer of the films on Tube B after 30, 90, and 180 days’ immersion, while it was observed in the film on Tube A only after 180 days’ immersion. The nature of the inner layer plays a crucial role in the erosion–corrosion resistance of the 90Cu–10Ni tubes at higher flow velocity. The film with a compact and continuous inner layer of Cu2O doped with Ni2+ and Ni3+ which bonds firmly with the substrate could survive and even get repaired with the increased flow velocity. The film on Tube B possessing a hollow and discontinuous inner layer composed of the residual substrate was degraded rapidly with increasing rotation speed in spite of its quite good resistance at the stagnant or lower speed conditions.
PubDate: 2018-11-01
DOI: 10.1007/s40195-018-0745-1
Issue No: Vol. 31, No. 11 (2018)

• Corrosion Behavior of Epoxy-Coated Rebar with Pinhole Defect in Seawater
Concrete
• Authors: Yao-Zong Mao; Ying-Hua Wei; Hong-Tao Zhao; Chen-Xi Lv; Hai-Jiao Cao; Jing Li
Pages: 1171 - 1182
Abstract: Abstract Experiments were carried out to investigate the corrosion behavior of epoxy-coated rebar (ECR) with pinhole defect (diameter in hundreds of microns) immersed in the uncarbonated/carbonated simulated pore solution (SPS) of seawater concrete. Corrosion behavior was analyzed by electrochemical impedance spectroscopy. The composition and morphology of corrosion products were characterized by X-ray diffraction, energy-dispersive spectrometry and scanning electron microscopy. Meanwhile, oxide film produced by preheating before spray coating was investigated by X-ray photoelectron spectroscopy and Mott–Schottky technology. Results indicated that corrosion behavior of ECR with pinhole defect exhibited three stages when immersed in the uncarbonated/carbonated SPS. In the initial stage, steel in defect was passivated when exposed in the uncarbonated SPS and corroded when exposed in the carbonated SPS, due to competitive adsorption between chloride and hydroxyl ions. In the second stage, the oxide film under coating reconstituted (the thickness and defects density decreasing) in the uncarbonated SPS, which was caused by the synergy between high hydroxide and chloride activity, while in the carbonated SPS, crevice corrosion happened under the coating around pinhole, because of the different oxygen concentrations cell at the coating/steel interface. In the third stage, localized corrosion occurred under the coating around the pinhole in the uncarbonated SPS, which was probably induced by ion diffusion at the nano-scale coating/steel interface. The corrosion products adjacent to the defects were re-oxidized from FeCl2·4H2O and Fe2(OH)3Cl to Fe2O3·H2O, and the corrosion area was expanded outward in the carbonated SPS.
PubDate: 2018-11-01
DOI: 10.1007/s40195-018-0755-z
Issue No: Vol. 31, No. 11 (2018)

• Dissimilar Joining of Pure Copper to Aluminum Alloy via Friction Stir
Welding
• Authors: Farhad Bakhtiari Argesi; Ali Shamsipur; Seyyed Ehsan Mirsalehi
Pages: 1183 - 1196
Abstract: Abstract In this study, the dissimilar friction stir welding (FSW) butt joints between aluminum alloy 5754-H114 and commercially pure copper were investigated. The thickness of welded plates was 4 mm and the aluminum plate was placed on the advancing side. In order to obtain a suitable flow and a better material mixing, a 1-mm offset was considered for the aluminum plate, toward the butt centerline. For investigating the microstructure and mechanical properties of FSWed joints, optical microscopy and mechanical tests (i.e., uniaxial tensile test and microhardness) were used, respectively. Furthermore, the analysis of intermetallic compounds and fracture surface was examined by scanning electron microscopy and X-ray diffraction. The effect of heat generation on the mechanical properties and microstructure of the FSWed joints was investigated. The results showed that there is an optimum amount of heat input. The intermetallic compounds formed in FSWed joints were Al4Cu9 and Al2Cu. The best results were found in joints with 1000 rpm rotational speed and 100 mm/min travel speed. The tensile strength was found as 219 MPa, which reached 84% of the aluminum base strength. Moreover, maximum value of the microhardness of the stir zone (SZ) was attained as about 120 HV, which was greatly depended on the grain size, intermetallic compounds and copper pieces in SZ.
PubDate: 2018-11-01
DOI: 10.1007/s40195-018-0741-5
Issue No: Vol. 31, No. 11 (2018)

• Precipitation Characteristics and Mechanism of Vanadium Carbides in a
V-Microalloyed Medium-Carbon Steel
• Authors: Xiao-Lin Pan; Minoru Umemoto
Pages: 1197 - 1206
Abstract: Abstract The precipitation characteristics and mechanism of vanadium carbides during isothermal transformation at 650 °C in a V-microalloyed medium-carbon steel were investigated through scanning electron microscopy and transmission electron microscopy as well as dilatometry test. Five morphologies of vanadium carbides were found to precipitate at different nucleation sites during the transformation. Two kinds of interphase precipitation form simultaneously in both pro-eutectoid and pearlitic ferrites. The linear arrays of fine interphase precipitates are parallel to the γ/α interface, and the fine needles of interphase precipitates are perpendicular to the γ/α interface. The vanadium carbides of long or short fibers, coarse particles and fine particles form in both pro-eutectoid and pearlitic ferrites, displaying different precipitation distributions and orientation relationships with ferrite. The precipitation mechanisms of vanadium carbide precipitates with different modes were proposed, and the precipitation sequence of various vanadium carbide precipitates was finally ascertained.
PubDate: 2018-11-01
DOI: 10.1007/s40195-018-0775-8
Issue No: Vol. 31, No. 11 (2018)

• Fe-Based Powders Prepared by Ball-Milling with Considerable Degradation
Efficiency to Methyl Orange Compared with Fe-Based Metallic Glasses
• Authors: Sheng-Hui Xie; Guang-Qiang Peng; Xian-Meng Tu; Hai-Xia Qian; Xie-Rong Zeng
Pages: 1207 - 1214
Abstract: Abstract In this study, the degradation efficiencies of zero-valent iron (ZVI) powders with different structures and components were evaluated for methyl orange (MO). The results show that the structure is an essential factor that affects degradation, and added non-metallic elements help optimize the structure. The amorphous and balled-milled crystalline Fe70Si10B20 has comparative degradation efficiencies to MO with t1/2 values of 6.9 and 7.0 min, respectively. Increasing the boron content can create a favorable structure and promote degradation. The ball-milled crystalline Fe70B30 and Fe43.64B56.36 powders have relatively short t1/2 values of 5.2 and 3.3 min, respectively. The excellent properties are mainly attributed to their heterogeneous structure with boron-doped active sites in ZVI. Composition segregation in the nanoscale range in an amorphous FeSiB alloy and small boron particles in the microscale range embedded in large iron particles prepared by ball-milling, both constitute effective galvanic cells that promote iron electron loss and therefore decompose organic chemicals. These findings may provide a new, highly efficient, low-cost commercial method for azo dye wastewater treatment using ZVI.
PubDate: 2018-11-01
DOI: 10.1007/s40195-018-0751-3
Issue No: Vol. 31, No. 11 (2018)

• EBSD Study of Microstructural and Textural Changes of Hot-Rolled
Ti–6Al–4V Sheet After Annealing at 800 °C
• Authors: Ji-Ying Xia; Lin-Jiang Chai; Hao Wu; Yan Zhi; Yin-Ning Gou; Wei-Jiu Huang; Ning Guo
Pages: 1215 - 1223
Abstract: Abstract In this paper, electron backscatter diffraction and various other characterization and analysis techniques including X-ray diffraction, electron channeling contrast imaging and energy-dispersive spectrometry were jointly employed to investigate microstructural and textural changes of a hot-rolled Ti–6Al–4V (TC4) sheet after annealing at 800 °C for 5 h. In addition, the hardness variation induced by the annealing treatment is rationalized based on revealed microstructural and textural characteristics. Results show that the TC4 sheet presents a typical dual-phase (α + β) microstructure, with α-Ti as the major phase and short-rod-shaped β-Ti (minority) uniformly distributed throughout the α matrix. Most of α grains correspond to the un-recrystallized structures with a typical rolling texture (c//TD and <11–20>//ND) and dense low angle boundaries (LABs). After the annealing, the stored energy in the as-received specimen is significantly reduced, along with greatly decreased LABs density. Also, the annealing allows recrystallization and grain growth to occur, leading to weakening of the initial texture. Furthermore, the water quenching immediately after the annealing triggers martensitic transformation, which makes the high-temperature β phases be transformed into submicron α plates. The hardness of the annealed specimen is 320.5 HV, lower than that (367.0 HV) of the as-received specimen, which could be attributed to reduced LABs, grain growth and weakened texture. Nevertheless, the hardening effect from the fine martensitic plates could help to suppress a drastic hardness drop.
PubDate: 2018-11-01
DOI: 10.1007/s40195-018-0768-7
Issue No: Vol. 31, No. 11 (2018)

• Effect of Heat Treatment on the Microstructure and Mechanical Properties
of the Modified 718 Alloy
• Authors: Da-Wei Han; Lian-Xu Yu; Fang Liu; Bin Zhang; Wen-Ru Sun
Pages: 1224 - 1232
Abstract: Abstract M718 alloy with an extra high Mo content of 7.50 wt% which reduced Nb addition and increased Al and Ti additions within the composition specifications of 718 alloy has been designed to increase the service temperature of 718 alloy. And the effect of the heat treatment on the microstructure and mechanical properties of M718 alloy has been investigated in this study. The results showed that Laves phase precipitated on the grain boundaries of M718 alloy instead of δ-Ni3Nb phase in 718 alloy, and γ′′ and γ′ phases precipitated in the matrix of M718 alloy as that in 718 alloy. Increasing the solution temperature from 960 to 1050 °C noticeably reduced the intergranular precipitation of Laves phase. The precipitation of Laves phase was appropriate at 1020 °C for improving the grain boundary cohesion. Increasing the two-stage aging temperatures markedly increased the sizes of γ′′ and γ′ phases. As a result, the strength of M718 alloy increased.
PubDate: 2018-11-01
DOI: 10.1007/s40195-018-0790-9
Issue No: Vol. 31, No. 11 (2018)

• Effects of Passes on Microstructure Evolution and Mechanical Properties of
Mg–Gd–Y–Zn–Zr Alloy During Multidirectional Forging
• Authors: Bing Li; Bu-Gang Teng; De-Gao Luo
Pages: 1009 - 1018
Abstract: Abstract The multidirectional forging (MDF) process was conducted at temperature of 753 K to optimize the mechanical properties of as-homogenized Mg–13Gd–4Y–2Zn–0.6Zr alloy containing long-period stacking ordered phase. The effects of MDF passes on microstructure evolution and mechanical properties were also investigated. The results show that both the volume fraction of dynamic recrystallization (DRX) grains and mechanical properties of the deformed alloy enhanced with MDF passes increasing till seven passes. The average grain size decreased from 76 to 2.24 μm after seven passes, while the average grain size increased to 7.12 μm after nine passes. The microstructure after seven passes demonstrated randomly oriented fine DRX grains and larger basal (0001)<11 $$\bar{2}$$ 0> Schmid factor of 0.31. The superior mechanical properties at room temperature (RT) with ultimate tensile strength (UTS) of 416 MPa and fracture elongation of 4.12% can be obtained after seven passes. The mechanical properties at RT after nine passes are inferior to those after seven passes due to the coarsening of DRX grains, which can be ascribed to the static recovery resulting from the repeated heating at the interval of MDF passes. The elevated temperature mechanical properties of the deformed alloy after seven passes and nine passes were investigated. When test temperature was below 523 K, the elevated temperature tensile yield strength and UTS after seven passes are superior to those after nine passes, while they are inferior to that after nine passes as temperature exceeds 523 K.
PubDate: 2018-10-01
DOI: 10.1007/s40195-018-0769-6
Issue No: Vol. 31, No. 10 (2018)

• CO Catalytic Oxidation of Pt-Loaded Perovskite BaTiO 3 Near
Ferroelectric-Phase Transition Temperature
• Authors: Si-Min Yin; Jia-Jie Duanmu; Yong-Feng Yuan; Shao-Yi Guo; Zhi-Chao Zhu; Zhao-Hui Ren; Gao-Rong Han
Pages: 1031 - 1037
Abstract: Abstract Perovskite BaTiO3 (BTO) nanocrystals with a size of 150–200 nm have successfully been synthesized via a facile hydrothermal method by employing titanate nanowires as synthetic precursor. Tetragonality and spontaneous ferroelectric polarization of BTO nanocrystals have been determined by X-ray diffraction and transmission electron microscopy investigations. BTO nanocrystals loaded with Pt nanoparticles in a size of 2–5 nm have been explored as a catalyst towards CO oxidation to CO2. It is interesting to find that CO catalytic conversion rate over Pt-BTO nanocrystals gradually decreased and further increased near 100 °C when the catalytic temperature keeps increasing, whereas the conversion behavior in oxides is expected to be enhanced upon the catalytic temperature grows. Using differential scanning calorimetry and first-principle calculations, the observed catalytic behavior has been discussed on the basis of the ferroelectric polarization effect and the ferroelectric–paraelectric transition of BTO nanocrystals with a Curie temperature of ~ 110 °C. Below Curie temperature, CO catalytic oxidation could be significantly tailored by ferroelectric polarization of BTO nanocrystals via a promoted dissociation of O2 molecules. The findings suggest that a ferroelectric polarization in perovskite oxides could be an alternative way to modify the CO catalytic oxidation.
PubDate: 2018-10-01
DOI: 10.1007/s40195-018-0757-x
Issue No: Vol. 31, No. 10 (2018)

• Effect of Pre-deformation on Grain Ultrafining by Intercritical
Deformation in Low-Carbon Microalloyed Steels
• Authors: Ba Li; Qing-You Liu; Shu-Jun Jia; Yi Ren; Bing Wang
Pages: 1038 - 1048
Abstract: Abstract In this study, the effect of pre-deformation at recrystallization and non-recrystallization zone on the grain ultrafining by the subsequent intercritical deformation (ID) was investigated on low-carbon microalloyed steel. The results showed that ultrafine grain microstructure with an average size of ~ 1.0 μm was fabricated through pre-deformation in the recrystallization zone followed by ID. When pre-deformed at the non-recrystallization zone prior to ID, the grain size increased to 1.6 μm with a heterogeneous distribution along with the well-developed dynamic recovery of ferrite. The grain ultrafining mechanism was attributed to the combined action of the deformation-induced ferrite transformation and the continuous dynamic recrystallization. In particular, the continuous dynamic recrystallization process during ID occurred on the pro-eutectoid ferrite as a result of the subgrain rotation mechanism and the absorbing dislocations mechanism.
PubDate: 2018-10-01
DOI: 10.1007/s40195-018-0767-8
Issue No: Vol. 31, No. 10 (2018)

• Tribocorrosion Behavior of 304 Stainless Steel in 0.5 mol/L Sulfuric
Acid
• Authors: Ming Liu; De-Li Duan; Sheng-Li Jiang; Ming-Yang Li; Shu Li
Pages: 1049 - 1058
Abstract: Abstract The tribocorrosion behavior of 304 stainless steel was studied through comparing the damage behavior of 304 stainless steel in dilute sulfuric acid to that in distilled water by a reciprocating tribotester. The re-passivation behavior, the surface and sectional morphological features, as well as the change of microhardness of samples were studied, and the tribocorrosion mechanism was also discussed. The experimental results reveal that the damage of stainless steel in dilute sulfuric acid was caused by the steel’s mechanical removal and electrochemical dissolution. The wear mechanism of stainless steel is abrasive wear, which mainly consists of micro-cutting and peeling. The synergetic action between corrosion and wear is notable. The corrosive environment leads to the embrittlement of the surface layer, and the wear destroys the passivation film and causes galvanic corrosion.
PubDate: 2018-10-01
DOI: 10.1007/s40195-018-0773-x
Issue No: Vol. 31, No. 10 (2018)

• Control of Secondary Phases by Solution Treatment in a N-Alloyed High-Mn
Cryogenic Steel
• Authors: Xiao-Jiang Wang; Xin-Jun Sun; Cheng Song; Shuai Tong; Luo-Jin Liu; Huan Chen; Wei Han; Feng Pan
Pages: 1059 - 1072
Abstract: Abstract The secondary phases of the steels have significant effects on the microstructure and mechanical properties, making controlling these secondary phases important. The control of MnS inclusions and AlN precipitates in a N-alloyed high-Mn twin-induced plastic cryogenic steel via solution treatment was investigated with several different techniques including microstructural characterization, 298 K tensile testing, and 77 K impact testing. The solutionizing temperature (ST) increased from 1323 to 1573 K, where the elongated MnS inclusions and large-sized AlN precipitates became spheroidized and dissolved. The aspect ratio of the MnS inclusions decreased as the ST increased and the number density increased. The impact toughness of the steels showed anisotropy and low impact energy values, due to the elongated MnS inclusions and large-sized AIN precipitates. The anisotropy was eliminated by spheroidizing the MnS inclusions. The impact energy was improved by dissolving the large-sized AlN precipitates during the solution treatment. The austenite grain size increased when the dissolution of the AlN precipitate increased, but the effect of the grain size on the yield strength, toughness, and the strength–ductility balance was weak.
PubDate: 2018-10-01
DOI: 10.1007/s40195-018-0759-8
Issue No: Vol. 31, No. 10 (2018)

• Friction and Wear Behavior of AlTiN-Coated Carbide Balls Against SKD11
Hardened Steel at Elevated Temperatures
• Authors: Rui Wang; Hai-Juan Mei; Ren-Suo Li; Quan Zhang; Teng-Fei Zhang; Qi-Min Wang
Pages: 1073 - 1083
Abstract: Abstract In this study, AlTiN coatings were deposited on YT14 cemented carbide balls by arc ion plating technique. The friction and wear behavior of the AlTiN-coated balls against SKD11 hardened steel was investigated by sliding tests using a ball-on-disk tribometer at various temperatures from 25 to 700 °C in air. The results showed that the friction and wear behavior was significantly influenced by the testing temperature. Obvious fluctuations were observed in the friction curves at elevated temperatures, which could be attributed to the formation and rupture of unstable Fe and Cr oxide layers. As the temperature increased from 25 to 500 °C, the wear rate of the coated balls increased from the scale of 10−21–10−20 m3/N m, and then decreased to 10−22 m3/N m as the temperature further increased to 700 °C. It was also found that the friction and wear behavior of the coated balls was directly dependent on the counterpart materials. As the temperature increased, the main wear mechanism of the coated balls changed from mild abrasive wear and adhesive wear to abrasive wear failure at 500 °C, and then transferred to adhesive wear and mild oxidation wear at 700 °C. For SKD11 hardened steel, the primary wear mechanism changed from delamination wear to abrasive wear and then transferred to plastic deformation and fatigue wear, accompanied by adhesive wear and tribo-oxidation wear.
PubDate: 2018-10-01
DOI: 10.1007/s40195-018-0753-1
Issue No: Vol. 31, No. 10 (2018)

• Achieving High Strength and High Electrical Conductivity in a CuCrZr Alloy
Using Equal-Channel Angular Pressing
• Authors: Yun-Xiang Tong; Yu Wang; Zhi-Min Qian; Dian-Tao Zhang; Li Li; Yu-Feng Zheng
Pages: 1084 - 1088
Abstract: Abstract In the present work, a CuCrZr alloy characterized by ultrafine grains and nanoscale particles was prepared by equal-channel angular pressing (ECAP) at 450 °C. A desired combination of a tensile strength (580 MPa) and an electrical conductivity (81% International Annealed Copper Standard) is simultaneously obtained in the as-ECAP-processed CuCrZr alloy without additional aging treatment. The improved properties can be mainly attributed to the ultrafine grains and nanoscale precipitates. This processing may pave a way to develop the CuCrZr alloys having high strength and high electrical conductivity for engineering applications.
PubDate: 2018-10-01
DOI: 10.1007/s40195-018-0766-9
Issue No: Vol. 31, No. 10 (2018)

• Influence of Cryorolling on the Precipitation of Cu–Ni–Si Alloys: An
In Situ X-ray Diffraction Study
• Authors: Wei Wang; Zong-Ning Chen; En-Yu Guo; Hui-Jun Kang; Yi Liu; Cun-Lei Zou; Ren-Geng Li; Guo-Mao Yin; Tong-Min Wang
Pages: 1089 - 1097
Abstract: Abstract The effect of cryorolling on the precipitation process of deformed Cu–Ni–Si alloys was investigated through in situ synchrotron X-ray diffraction technique. The results demonstrate that the precipitation process is significantly accelerated by cryorolling. Cryorolling produces higher dislocation density, which provides more heterogeneous nucleation sites for Ni2Si precipitates, hence promotes precipitation. In the early stage of aging, the enhanced nucleation of precipitates accelerates the depletion of supersaturation, and finer precipitates are obtained. In addition, recrystallization is promoted as a result of high stored energy in the cryorolled Cu–Ni–Si alloys, which facilitates the formation of discontinuous precipitation in the late stage of aging.
PubDate: 2018-10-01
DOI: 10.1007/s40195-018-0781-x
Issue No: Vol. 31, No. 10 (2018)

• Effect of Sintering Temperature and Heating Rate on Crystallite Size,
Densification Behaviour and Mechanical Properties of Al-MWCNT
Nanocomposite Consolidated via Spark Plasma Sintering
• Authors: Lavish Kumar Singh; Alok Bhadauria; Subhodeep Jana; Tapas Laha
Abstract: Abstract Powder mixture of ball-milled aluminium and functionalized multi-walled carbon nanotubes was compacted via spark plasma sintering (SPS) to study effects of sintering temperature and heating rate. An increase in sintering temperature led to an increase in crystallite size and density, whereas an increase in heating rate exerted the opposite effect. The crystallite size and relative density increased by 85.0% and 14.3%, respectively, upon increasing the sintering temperature from 400 to 600 °C, whereas increasing the heating rate from 25 to 100 °C/min led to respective reduction by 30.0% of crystallite size and 1.8% of relative density. The total punch displacement during SPS for the nanocomposite sintered at 600 °C (1.96 mm) was much higher than that of the sample sintered at 400 °C (1.02 mm) confirming positive impact of high sintering temperature on densification behaviour. The maximum improvement in mechanical properties was exhibited by the nanocomposite sintered at 600 °C at a heating rate of 50 °C/min displaying microhardness of 81 ± 3.6 VHN and elastic modulus of 89 ± 5.3 GPa. The nanocomposites consolidated at 400 °C and 100 °C/min, in spite of having relatively smaller crystallite size, exhibited poor mechanical properties indicating the detrimental effect of porosity on the mechanical properties.
PubDate: 2018-08-17
DOI: 10.1007/s40195-018-0795-4

• Effects of W Addition on the Electrochemical Behaviour and Passive Film
Properties of Fe-Based Amorphous Alloys in Acetic Acid Solution
• Authors: Dan-Dan Liang; Xian-Shun Wei; Chun-Tao Chang; Jia-Wei Li; Yong Wang; Xin-Min Wang; Jun Shen
Abstract: Abstract The electrochemical behaviour and passive film properties of Fe–Cr–Mo–W–C–B–Y amorphous alloys in acetic acid solution were investigated. The potentiodynamic polarisation and Nyquist curves demonstrated that W addition significantly enhanced the corrosion resistance. Mott–Schottky plots and angle-resolved X-ray photoelectron spectra indicated that passive films with different W contents exhibited dipolar (p–n) semiconducting characteristics separated by flat-band potentials. The outer and inner oxide layers of the passive films were modified by reducing the acceptor and donor densities. Moreover, W addition favoured the formation of a thicker and more stable passive film to inhibit the dissolution of alloy elements.
PubDate: 2018-08-17
DOI: 10.1007/s40195-018-0791-8

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