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Effect of high anodic polarization on the passive layer properties of superduplex stainless steel friction stir welds at different chloride electrolyte pH values and temperatures
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L. A. Santa-Cruz G. Machado A. A. Vicente T. F. C. Hermenegildo T. F. A. Santos 《矿物冶金与材料学报》2019,26(6):710-721
The conditions used for friction stir welding of duplex stainless steels determine the resulting mechanical and corrosion performance of the material.This study investigates the corrosion resistance of UNS S32750 and S32760 superduplex stainless steels(SDSSs)joined by friction stir welding,employing cyclic polarization,Mott–Schottky,and microscopy techniques for analysis.The microscopy images indicated the presence of a deleterious intermetallic phase after electrolytic etching of S32760,as well as decreased corrosion resistance.The presence of molybdenum in the steels promoted better passive behavior at low pH.The Mott–Schottky curves revealed p-n heterojunction behavior of the passive oxide.Images acquired after the polarization test by scanning electron microscopy showed higher passivation propensity with increases of temperature and pH. 相似文献
34.
Interface microstructure and formation mechanism of ultrasonic spot welding for Al–Ti dissimilar metals
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Li Zhou Shan Liu Jie Min Zhi-Wei Qin Wen-Xiong He Xiao-Guo Song Hong-Bo Xu Ji-Cai Feng 《矿物冶金与材料学报》2021,28(9):1506-1514
The present study focuses on interface microstructure and joint formation. AA6061 aluminum alloy (Al) and commercial pure ti-tanium (Ti) joints were welded by ultrasonic spot welding (USW). The welding energy was 1100–3200 J. The Al–Ti joint appearance and in-terface microstructure were observed mainly via optical microscopy and field emission scanning electron microscopy. Results indicated that a good joint can be achieved only with proper welding energy of 2150 J. No significant intermetallic compound (IMC) was found under all con-ditions. The high energy barriers of Al–Ti and difficulties in diffusion were the main reasons for the absence of IMC according to kinetic ana-lysis. The heat input is crucial for the material plastic flow and bonding area, which plays an important role in the joint formation. 相似文献
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Hua-bao Yang Liang Wu Bin Jiang Bin Lei Ming Yuan Hong-mei Xie Andrej Atrens Jiang-feng Song Guang-sheng Huang Fu-sheng Pan 《矿物冶金与材料学报》2021,28(10):1705-1715
Mg–Sn–Y alloys with different Sn contents (wt%) were assessed as anode candidates for Mg-air batteries. The relationship between microstructure (including the second phase, grain size, and texture) and discharge properties of the Mg–Sn–Y alloys was examined using mi-crostructure observation, electrochemical measurements, and galvanostatic discharge tests. The Mg–0.7Sn–1.4Y alloy had a high steady dis-charge voltage of 1.5225 V and a high anodic efficiency of 46.6% at 2.5 mA·cm?2. These good properties were related to its microstructure:small grain size of 3.8 μm, uniform distribution of small second phase particles of 0.6 μm, and a high content (vol%) of (11(2)0)/(10(1)0) orient-ated grains. The scanning Kelvin probe force microscopy (SKPFM) indicated that the Sn3Y5 and MgSnY phases were effective cathodes caus-ing micro-galvanic corrosion which promoted the dissolution of Mg matrix during the discharge process. 相似文献
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《自然科学进展(英文版)》2022,32(1):114-127
The effect of a small amount of Zr addition on the temperature-dependent stability of Laves phase particles and mechanical properties of Fe-13.5Cr-4.73Al-2.07Mo-(0.34–0.5)Nb-(0.65–0.98)Ta-(0–0.33)Zr (wt. %) ferritic alloys was investigated in the present study. The designed alloy ingots were hot-rolled, aged at 1073 ?K for 24 ?h, and then re-treated at 1273 ?K, 1323 ?K, 1373 ?K, and 1473 ?K for 1 ?h, respectively. It was found that the Zr addition could not only stabilize the Fe2M Laves phase (M ?= ?Mo,Nb,Ta,Zr) to a much higher temperature, but also induce the formation of stable Fe23Zr6 phase. The high-temperature (HT) microstructural stability of the alloys significantly was improved, as evidenced by the fact that a certain amount (0.66–1.19%) of precipitates (Fe2M, Fe23Zr6, and core(Fe23Zr6)-shell(Fe2M)-structured particles) with an appropriate size (~1.0 ?μm) uniformly distributed in the ferritic matrix even after being re-treated at 1473 ?K. Particularly, the formation of core-shell-structured particles at HTs was studied from the viewpoint of both solid solubility and diffusion coefficient of M in the matrix. All these aged alloys exhibited prominent mechanical properties at both room and elevated temperatures, showing high yield strength with σYS ?= ?490–560 ?MPa at room-temperature and σYS ?= ?80–85 ?MPa at 1073 ?K. The strengthening effect was further discussed in light of various strengthening mechanisms, and the calculated strength are in good agreement with the experimental results. 相似文献
37.
数据实时压缩处理模型与程序设计 总被引:1,自引:0,他引:1
数据实时压缩处理是数据采集处理的关键技术,内容包括峰谷值检测和无效幅值去除,其中“最短航道法”无效幅值去除模型构思巧妙,物理概念直观,压缩效果显著,并具备实时处理功能。本模型已用于某型发动机历程记录仪软件设计中,解决了小型机载记录仪数据压缩处理的关键技术问题,居国内领先水平。本无效幅值去除模型也可用于其他数据处理使用。 相似文献
38.
天然软黏土普遍具有结构性。结构性黏土在我国湛江地区分布广泛,该区域黏土具有天然含水率高、孔隙比大、高压缩性和低渗透性等特点,其土体结构特征对其变形特性有较大影响。以湛江市东海岛地区灰色结构性黏土为研究对象,通过室内试验研究其在加载作用下的压缩特性,以及在卸载作用下的回弹特性。主要结论如下:1天然原状土与重塑土的压缩特性存在较大差异,以重塑土为试验对象测得的土体力学指标不能很好的代表实际工程中原状土的力学特性;2天然原状土在加载阶段和卸载阶段的变形规律有相同之处,但土体在卸载阶段产生的总回弹变形量远小于加载阶段产生的总压缩变形量;3天然原状土存在临界卸荷比R为0.25和0.75,当0R≤0.25时,土样回弹变形量很小;当0.25R0.75时,土样发生回弹变形;当R≥0.75时,土体发生明显回弹变形,且此阶段回弹变形量占总回弹变形量比例最大。 相似文献
39.
随着社会的进步,计算机技术的出现,科技的创新,人们生产生活方式日益数字化,数字媒体出现并得到迅速发展。文章介绍了数字媒体的概念及数字媒体的特点,针对发展迅速的数字媒体,就数字媒体信息压缩的必要性和可行性进行论证分析,按出发点进行分类介绍了几种数字媒体信息压缩方法.应用Huffman编码和行程编码两种不同的编码方式针对两个不同的实例分别加以论证说明.就数字媒体信息压缩技术的未来发展进行展望。 相似文献
40.
为了研究配箍率对高强箍筋活性粉末混凝土梁抗剪性能的影响,开展6根配置HRB400级箍筋RPC梁的抗剪试验,考虑RPC的材料特征参数与钢纤维对斜截面承载力的影响,分析有腹筋与无腹筋梁在剪力传递机理及裂缝控制方面的差异,基于修正压力场理论,对开裂混凝土在拉、压应力下的本构关系及裂缝处的应力平衡条件进行适当修正,将弯矩效应叠加至纯剪作用建立RPC梁在弯剪复合作用下的分析模型,并根据弯剪复合作用采用MATLAB软件编制RPC梁斜截面抗剪强度分析计算程序,对RPC简支梁进行受剪强度分析,并将试验结果与计算结果进行对比分析,研究结果表明该计算程序能够较好地预测高强钢筋RPC梁的受剪承载力,具有一定的参考和实用价值。 相似文献