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ISSN: 1006-7191
CN: 21-1361/TG
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China Association for Science and Technology
The Chinese Society For Metals
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Institute of Metal Research, Chinese Academy of Science

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 10 December 2019, Volume 32 Issue 12 Previous Issue
Orginal Article
 Select Effects of Temperature on Fretting Corrosion Between Alloy 690TT and 405 Stainless Steel in Pure Water Xing-Chen Liu, Hong-Liang Ming, Zhi-Ming Zhang, Jian-Qiu Wang, Li-Chen Tang, Hao Qian, Yong-Cheng Xie, En-Hou Han Acta Metallurgica Sinica(English letters). 2019, 32 (12): 1437-1448.   DOI: 10.1007/s40195-019-00929-9 Abstract   HTML   PDF (6195KB) In pressurized water reactor, fretting corrosion has become the main reason for the failure of 690TT heat exchanger tubes. The effect of temperature on the fretting corrosion behavior between 690TT tube and 405 stainless steel (SS) bar has been studied during 106 fretting cycles. The overall average coefficient of friction (COF) values descends with an increase in test temperature, while the width of worn scar becomes wider. The severest fretting corrosion happens when the test temperature is at 100 °C. The wear mechanism differs at different test temperatures, from adhesive wear at room temperature to abrasive wear and delamination at 100 °C, to abrasive wear at 200 °C. Deformation slips, high residual strain concentration, and micro-cracks are found which are disadvantageous for the further service performance of the tubes.
 Select Effects of Dissimilar Alumina Particulates on Microstructure and Properties of Cold-Sprayed Alumina/A380 Composite Coatings Xiang Qiu, Naeem ul Haq Tariq, Lu Qi, Jun-Rong Tang, Xin-Yu Cui, Hao Du, Ji-Qiang Wang, Tian-Ying Xiong Acta Metallurgica Sinica(English letters). 2019, 32 (12): 1449-1458.   DOI: 10.1007/s40195-019-00917-z Abstract   HTML   PDF (2961KB) In this study, alumina/A380 composite coatings were fabricated by cold spray. The influence of alumina particulates’ morphology (spherical and irregular) and content on the deposition behavior of the coatings (including surface roughness, surface residual stress, cross-sectional microstructure and microhardness) was investigated. Results revealed that the spherical alumina mainly shows micro-tamping effect during deposition, which result in remarkable low surface roughness and porosity of the coatings. In addition, very low deposition efficiency and good interfacial bonding between the coating and the substrate were achieved. For irregular alumina particles, the embedding of ceramic particulates in the coating was dominant during deposition process, resulting in high retention in the final deposit. However, it showed limited influence on porosity, surface roughness and interfacial bonding of the deposit. The coatings containing irregular alumina particulates exhibited much higher microhardness than those containing spherical alumina due to the higher load-bearing capacity of deposited alumina.
 Select Effect of Cl- Concentration on the SCC Behavior of 13Cr Stainless Steel in High-Pressure CO2 Environment Jin-Jin Zhao, Xian-Bin Liu, Shuai Hu, En-Hou Han Acta Metallurgica Sinica(English letters). 2019, 32 (12): 1459-1469.   DOI: 10.1007/s40195-019-00923-1 Abstract   HTML   PDF (3859KB) An effect of Cl- concentration on the stress corrosion cracking (SCC) behavior of 13Cr stainless steel was investigated by employing electrochemical measurements and the slow strain rate tensile tests. These tests were conducted in various solutions with different concentrations of NaCl at 90 °C under 3 MPa CO2 with 3 MPa N2. The results indicate that the passive film of the specimen formed in the 10% NaCl solution has the best protective effect on the matrix. The SCC susceptibility does not increase with increasing the chloride ion concentration, the lowest SCC susceptibility occurs when the NaCl concentration is 10%, and the specimens show higher SCC susceptibility in the 5% NaCl and 20% NaCl solutions.
 Select Corrosion and Cavitation Erosion Behaviours of Cast Nickel Aluminium Bronze in 3.5% NaCl Solution with Different Sulphide Concentrations Qi-Ning Song, Nan Xu, Yao Tong, Chen-Ming Huang, Shou-Yu Sun, Chen-Bo Xu, Ye-Feng Bao, Yong-Feng Jiang, Yan-Xin Qiao, Zhi-Yuan Zhu, Zheng-Bin Wang Acta Metallurgica Sinica(English letters). 2019, 32 (12): 1470-1482.   DOI: 10.1007/s40195-019-00963-7 Abstract   HTML   PDF (4621KB) The effect of sulphide (Na2S) concentration (SC) on the corrosion and cavitation erosion behaviours of a cast nickel aluminium bronze (NAB) in 3.5% NaCl solution is investigated in this study. The results show that when the SC exceeds 50 ppm, the hydrogen evolution reaction dominates the cathodic process, and a limiting current region appears in the anodic branch of the polarisation curve due to the formation of a copper sulphide film, which is a diffusion-controlled process. After long-term immersion, the increased mass loss rate of NAB with the sulphide additions of 20 and 50 ppm is attributed to the less protective films, which contains a mixture of copper oxides and sulphides. Moreover, NAB undergoes severe localised corrosion (selective phase corrosion, SPC) at the β′ phases and eutectoid microstructure α + κIII. By comparison, NAB undergoes general corrosion and a copper sulphide film is formed in 100 and 200 ppm sulphide solutions. Cavitation erosion greatly increases the corrosion rate of NAB in all solutions and causes a negative potential shift in 3.5% NaCl solution due to the film destruction. However, a positive potential shift occurs in the solutions with SC higher than 50 ppm due to the accelerated mass transfer of the cathodic process. The cavitation erosion mass loss rate of NAB increases with the increase of SC. The occurrence of severe SPC decreases the phase boundary cohesion and causes brittle fracture under the cavitation impact. The corrosion-enhanced erosion is the most predominant factor for the cavitation erosion damage when the SC exceeds 50 ppm.
 Select Stern-Geary Constant for X80 Pipeline Steel in the Presence of Different Corrosive Microorganisms Yu-Peng Sun, Chun-Tian Yang, Chun-Guang Yang, Da-Ke Xu, Qi Li, Lu Yin, Cheng-Shuo Qiu, Dan liu, Ke Yang Acta Metallurgica Sinica(English letters). 2019, 32 (12): 1483-1489.   DOI: 10.1007/s40195-019-00902-6 Abstract   HTML   PDF (1585KB) The Stern-Geary constant (B value) is indispensable to measure the corrosion rate in the microbiologically influenced corrosion (MIC) systems. Linear polarization resistance (LPR) and weight loss methods were used to study the variation of B values for X80 pipeline steel in the presence of Pseudomonas aeruginosa, Acetobacter aceti and Desulfovibrio vulgaris. The results showed that B values in the presence of three different bacteria were 35.60 ± 0.55 mV, 33.00 ± 1.00 mV and 58.60 ± 0.55 mV, respectively, suggesting that the change of corrosion system significantly affected the B values of X80 pipeline steel. This work further indicated that the determination of B values is necessary to accurately measure the MIC rate by LPR method.
 Select Oxidation Performance and Interdiffusion Behavior of a Pt-Modified Aluminide Coating with Pre-deposition of Ni He Liu, Shuai Li, Cheng-Yang Jiang, Chun-Tang Yu, Ze-Bin Bao, Sheng-Long Zhu, Fu-Hui Wang Acta Metallurgica Sinica(English letters). 2019, 32 (12): 1490-1500.   DOI: 10.1007/s40195-019-00918-y Abstract   HTML   PDF (3357KB) To refrain the interdiffusion of elements while holding good oxidation resistance, a (Ni,Pt)Al/Ni composite coating was prepared by sequential treatments of electroplating Ni and Pt and successive gaseous aluminization. In comparison with normal (Ni,Pt)Al coating, high-temperature performance of the composite coating was evaluated in isothermal oxidation test at 1100 °C. Both the two coatings exhibited good resistance against high-temperature oxidation, but the interdiffusion of elements between composite coating and single-crystal (SC) superalloy substrate was greatly relieved, in which the thickness of secondary reaction zone (SRZ) and the amount of precipitated topologically close-packed phase in the SC alloy matrix were significantly decreased. Mechanisms responsible for delaying rate of coating degradation and SRZ growth/propagation are discussed.
 Select Effect of Co on Microstructure and Stress Rupture Properties of K4750 Alloy Xiao-Xiao Li, Mei-Qiong Ou, Min Wang, Xian-Chao Hao, Ying-Che Ma, Kui Liu Acta Metallurgica Sinica(English letters). 2019, 32 (12): 1501-1510.   DOI: 10.1007/s40195-019-00936-w Abstract   HTML   PDF (4606KB) The effects of substituting Co for Fe on the microstructure and stress rupture properties of K4750 alloy were studied. The microstructure of the alloy without Co (K4750 alloy) and the alloy containing Co (K4750-Co alloy) were analyzed. Substitution of Co for Fe inhibited the decomposition of MC carbide and the precipitation of η phase during long-term aging treatment. In K4750-Co alloy, the morphology of MC carbide at the grain boundary (GB) remained dispersed blocky shape and no η phase was observed after aging at 750 °C for 3000 h. However, in K4750 alloy, almost all the MC carbides at GBs broke down into granular M23C6 carbide and needle-like η phase. The addition of cobalt could delay the decomposition of MC carbides, which accordingly restricted the elemental supply for the formation of η phase. The stress rupture tests were conducted on two alloys at 750 °C/430 MPa. When Co is substituted for Fe in K4750 alloy, the stress rupture life increased from 164.10 to 264.67 h after standard heat treatment. This was mainly attributed to increased concentration of Al, Ti and Nb in γ′ phase in K4750-Co alloy, which further enhanced the strengthening effect of γ′ phase. After aging at 750 °C for 3000 h, substitution of Co for Fe can also cause the stress rupture life at 750 °C/430 MPa to increase from 48.72 to 208.18 h. The reason was mainly because MC carbide degradation and η phase precipitation in K4750 alloy, which promoted the initiation and propagation of micro-crack during stress rupture testing.
 Select Site Occupation of Nb in γ-TiAl: Beyond the Point Defect Gas Approximation Wei Diao, Li-Hua Ye, Zong-Wei Ji, Rui Yang, Qing-Miao Hu Acta Metallurgica Sinica(English letters). 2019, 32 (12): 1511-1520.   DOI: 10.1007/s40195-019-00925-z Abstract   HTML   PDF (2063KB) Microalloying is an effective approach to improve the mechanical properties of γ-TiAl intermetallic compound. Knowledge about the site occupancy of the ternary alloying element in the crystal lattice of γ-TiAl is highly demanded in order to understand the physics underlying the alloying effect. Previous first-principle methods-based thermodynamic models for the determination of the site occupancy were based on the point defect gas approximation with the interaction between the point defects neglected. In the present work, we include the point defect interaction energy in the thermodynamic model, which allows us to predict the site occupancy of the ternary alloying element in γ-TiAl beyond the point defect gas approximation. The model is applied to the γ-TiAl-Nb alloy. We show that, at low temperature, the site occupancy of Nb atoms depends on the composition of the alloy: Nb atoms occupy the Al sublattice for the Ti-rich alloy but occupy Ti sublattice for the Al-rich alloy. The fraction of Nb atoms occupying Al sublattice in the Ti-rich alloy decreases drastically, whereas the fraction of Nb atoms on the Ti sublattice in the Al-rich alloy decreases slightly with increasing temperature. At high temperature, Nb atoms occupy dominantly the Ti sublattice for both the Ti-rich and Al-rich alloys. The interaction between the point defects makes the Ti sublattice more favorable for the Nb atoms to occupy.
 Select Torsional Fatigue Cracking and Fracture Behaviors of Cold-Drawn Copper: Effects of Microstructure and Axial Stress Rong-Hua Li, Peng Zhang, Zhe-Feng Zhang Acta Metallurgica Sinica(English letters). 2019, 32 (12): 1521-1529.   DOI: 10.1007/s40195-019-00965-5 Abstract   HTML   PDF (2312KB) The fatigue cracking and fracture behavior of cold-drawn copper subjected to cyclic torsional loading were investigated in this study. It was found that with increasing stress amplitude, the fracture mode of cold-drawn copper gradually changes from a shear fracture on transverse maximum shear stress plane to a mixed shear mode on both transverse and longitudinal shear planes and finally turns to the shear fracture on multiple longitudinal shear planes. Combining the cracking morphology and the relationship between torsional fatigue cracking and the grain boundaries, the fracture mechanism of cold-drawn copper under cyclic torsional loading was analyzed and proposed by considering the effects of the microstructure and axial stress caused by torsion. Because of the promotion of the grain boundary distribution on longitudinal crack propagation and the inhibition of axial stress on transverse crack grown, the tendency of crack propagation along the longitudinal direction increases with increasing stress levels.
 Select Growth of Gallium Nitride Films on Multilayer Graphene Template Using Plasma-Enhanced Atomic Layer Deposition Ying-Feng He, Mei-Ling Li, San-Jie Liu, Hui-Yun Wei, Huan-Yu Ye, Yi-Meng Song, Peng Qiu, Yun-Lai An, Ming-Zeng Peng, Xin-He Zheng Acta Metallurgica Sinica(English letters). 2019, 32 (12): 1530-1536.   DOI: 10.1007/s40195-019-00938-8 Abstract   HTML   PDF (2218KB) In this work, the GaN thin films were directly deposited on multilayer graphene (MLG) by plasma-enhanced atomic layer deposition. The deposition was carried out at a low temperature using triethylgallium (TEGa) precursor and Ar/N2/H2 plasma. Chemical properties of the bulk GaN and GaN-graphene interface were analyzed using X-ray photoelectron spectroscopy. The sharp interface between GaN and graphene was verified via X-ray reflectivity and transmission electron microscope. The microstructures and the nucleation behaviors of the GaN grown on graphene have been also studied. The results of grazing incidence X-ray diffraction and Raman spectrum indicate that the as-deposited sample is polycrystalline with wurtzite structure and has a weakly tensile stress. Optical properties of the sample were investigated by photoluminescence (PL) at room temperature. The successful growth of GaN on MLG at a low temperature opens up the possibility of ameliorating the performance of electronic and optical devices based on GaN/graphene heterojunction.
 Select Hot Deformation Behavior and Processing Map of a Cu-Bearing 2205 Duplex Stainless Steel Tong Xi, Lu Yin, Chun-Guang Yang, Ke Yang Acta Metallurgica Sinica(English letters). 2019, 32 (12): 1537-1548.   DOI: 10.1007/s40195-019-00910-6 Abstract   HTML   PDF (2519KB) The hot deformation behavior and processing map of Cu-bearing 2205 duplex stainless steel (2205-Cu DSS) were investigated at temperatures of 950-1150 °C and strain rates of 0.01-10 s-1. The effects of Cu addition and different deformation parameters on deformation behavior were, respectively, characterized by analyzing flow curves, constitutive equations and microstructures. The results indicated that the shapes of flow curves strongly depended on the volume fraction of two phases. When deformed at low strain rate, DRV in ferrite was prompted with increase in the temperature and was further developed to continuous DRX. At high strain rate, flow localization preferentially occurred in ferrite at low deformation temperature due to the strain partitioning and relatively less fraction of ferrite. The activation energy for 2205-Cu DSS was 452 kJ/mol and was found to connect with the variation of strain, strain rate and deformation temperature. The optimum hot deformation parameters for 2205-Cu DSS were obtained in the temperature range of 1100-1150 °C and strain rate range of 0.1-1 s-1 with a peak power dissipation efficiency of 41%. Flow localization was the main way to lead to flow instability. Meanwhile, the Cu-rich precipitates were generated within a few ferrite grains when deformed at temperature lower than 1000 °C. The interaction between dislocations and Cu-rich precipitates at high strain rate, as well as the limited DRV in ferrite and DRX in austenite, contributed to the complex microstructure and flow behavior.
 Select Effect of Cooling Rate on Microstructure and Mechanical Properties of Sand-Casted Al-5.0Mg-0.6Mn-0.25Ce Alloy Hua-Ping Tang, Qu-Dong Wang, Chuan Lei, Kui Wang, Bing Ye, Hai-Yan Jiang, Wen-Jiang Ding Acta Metallurgica Sinica(English letters). 2019, 32 (12): 1549-1564.   DOI: 10.1007/s40195-019-00922-2 Abstract   HTML   PDF (17323KB) This study examines the relationship among cooling rate, microstructure and mechanical properties of a sand-casted Al-5.0Mg-0.6Mn-0.25Ce (wt%) alloy subjected to T4 heat treatment (430 °C × 12 h + natural aging for 5 days), and the tested alloys with wall thickness varying from 5 to 50 mm were prepared. The results show that as the cooling rate increases from 0.22 to 7.65 K/s, the average secondary dendritic arm spacing (SDAS, λ2) decreases from 94.8 to 27.3 μm. The relation between SDAS and cooling rate can be expressed by an equation: $\lambda_{2} = 53.0R_{\text{c}}^{ - 0.345}$. Additionally, an increase in cooling rate was shown not only to reduce the amount of the secondary phases, but also to promote the transition from Al10Mn2Ce to α-Al24(Mn,Fe)6Si2 phase. Tensile tests show that as the cooling rate increases from 0.22 to 7.65 K/s, the ultimate tensile strength (UTS) increases from 146.3 to 241.0 MPa and the elongation (EL) increases sharply from 4.4 to 12.2% for the as-cast alloys. Relations of UTS and EL with SDAS were determined, and both the UTS and EL increase linearly with (1/λ2)0.5 and that these changes can be explained by strengthening mechanisms. Most eutectic Al3Mg2 phases were dissolved during T4 treatment, which in turn further improve the YS, UTS and EL. However, the increment percent of YS, UTS and EL is affected by the cooling rate.
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