关键词： Magnesium alloy   Doublely-doped LDH film   Vanadate   Cerium   Anticorrosion  

摘要： A doublely-doped layered double hydroxide(LDH)film was produced on an anodized magnesium alloy *** Ce-doped Mg-Al LDH film was prepared by in-situ hydrothermal treatment method,and the intercalation of vanadate was realized by ion-exchange *** structure,morphology and composition of as-prepared LDH film were investigated by X-ray diffractometer,field-emission scanning electronic microscope and energy dispersive *** indicated that a uniform and compact LDH film was formed and the intercalation of Ce^(3+)and vanadate would change the crystal structure of *** results of the potentiodynamic polarization,electrochemical impedance spectra,hydrogen evolution and corrosion weight loss tests showed the Ce^(3+)and vanadate anions significantly improve the impedance of LDH film,and the active double-doped LDH film could effectively protect the magnesium substrate from corrosion.

关键词： 激光自熔焊   微观组织   力学性能   激光功率   AZ31镁合金  

摘要： 采用对接激光自熔焊方法焊接4 mm厚的AZ31镁合金,通过微观组织分析和力学性能测试研究了激光自熔焊工艺参数对镁合金激光焊接头焊缝成形、组织以及力学性能的影响。试验结果表明:采用试验范围内的工艺参数,可以获得焊缝成形良好、无明显焊接缺陷的接头。焊接速度从3 m/min增大到3.9 m/min,焊缝尺寸和接头抗拉强度变化较小。随着激光功率从2.4 kW增加到3.0 kW,接头抗拉强度逐渐减小。焊缝组织为晶粒均匀分布的等轴晶,其晶粒呈六角形,焊缝区硬度明显低于母材。当激光功率为2.4 kW、焊接速度为3 m/min时接头抗拉强度最高,为193 MPa。

关键词： 微弧氧化   稀土硝酸盐   润湿性   电化学分析  

摘要： 通过微弧氧化技术对镁合金表面改性,旨在获得拥有优良抗腐蚀性的陶瓷涂层。在硅酸盐电解液体系下对AZ31镁合金进行微弧氧化处理,研究Er(NO_(3))_(3)掺杂量变化对改性涂层相组成、微观结构、表面粗糙度、润湿角以及电化学性能的影响。结果表明,在电解液中掺杂和未掺杂稀土盐Er(NO_(3))_(3),获得的镁合金涂层均由MgO、MgSiO_(3)和Mg_(2)SiO_(4)等晶相组成,未检测到Er的氧化物相。掺杂稀土盐Er(NO_(3))_(3)后涂层中的MgSiO3相含量有所增加。未掺杂Er(NO_(3))_(3)时,涂层具有火山口状的微孔结构。随着Er(NO_(3))_(3)掺杂量增加,涂层表面的微孔数量呈现出先增加后降低的趋势。当Er(NO_(3))_(3)掺杂量超过4‰时,微弧氧化涂层微孔尺寸明显减小,出现较大区域的裂纹分布表面。在不同Er(NO_(3))_(3)掺杂量后获得涂层表面粗糙度在1.6~2.1μm。在电解液中引入Er(NO_(3))_(3)后,涂层腐蚀电位正向移动。与未添加Er(NO_(3))_(3)试样相比,掺杂Er(NO_(3))_(3)后获得的涂层腐蚀电流降低约1个数量级,涂层耐蚀性略有提高。

关键词： ZK61镁合金   带内筋筒形件   热强旋   感应加热   温度场  

摘要： 对于镁合金带内筋筒形件的热强旋成形,旋前管坯的温度场分布对成形过程中的材料流动及旋压件的成形质量具有重要影响。基于多物理场耦合软件COMSOL,建立了ZK61镁合金带内筋筒形件热强旋旋前管坯电磁感应加热模型,模拟分析了不同感应加热参数条件下管坯温度场的分布情况,并通过实验验证了模型的可靠性。研究结果表明:相比电流强度,电流频率对管坯表心温差的影响更为显著,随着电流频率及电流强度的增加,管坯表心温差均逐渐增大;感应线圈的匝数及线圈与管坯的间距对管坯表心温差的影响较大,随着线圈匝数的增大,管坯表心温差近似呈指数形式增加,线圈与管坯的间距越大,管坯表心温差越小。

关键词： cyclic extrusion compression angular pressing   AM60 alloy   strain distribution   mechanical properties   grain refinement  

摘要： A new severe plastic deformation(SPD)technique for improvement of the metallurgical properties of the magnesium alloys is *** this process,a cyclic extrusion compression angular pressing(CECAP)process is followed by an extrusion step in the outlet playing the role of additional back ***,more uniform and enhanced mechanical properties are expected in comparison with equal channel angular pressing(ECAP).In order to evaluate the effectiveness and capabilities of this new method,an AM60 magnesium alloy was *** element results exhibited a significant increase in strain values as well as uniform strain distribution for the new *** addition,~110%increase in compressive stress was observed in new method compared to the conventional *** results revealed a noticeable increase in the hardness and strength of the specimens processed by the new technique as a result of the formation of finer grains and more homogeneous microstructure with good distribution of refinedβ-phase along the *** may be concluded that the new process is very promising for future magnesium alloy products.

关键词： AZ91D镁合金   激光选区熔化   固溶处理   时效处理   显微组织   耐腐蚀性  

摘要： 目的研究热处理对激光选区熔化成形(Selective Laser Melting,SLM)AZ91D镁合金组织与耐蚀性能的影响。方法利用SLM技术成形了AZ91D镁合金,对试样进行固溶处理(T4)、固溶+时效处理(T6)。采用金相显微镜、扫描电镜、X射线衍射仪、电化学工作站分别对SLM、T4热处理、T6热处理的AZ91D镁合金试样的微观组织和耐蚀性能进行观察与测试。结果SLM试样经420℃保温6 h固溶处理后,β-Mg17Al12相基本固溶于基体中,晶粒尺寸由5μm增大至60μm左右。加热至200℃保温2 h时效处理后,β-Mg17Al12相从基体析出,随着时效时间由2 h增加至6 h,析出相数量逐渐增多。在3.5%NaCl溶液中浸泡120 h后,SLM试样表面腐蚀坑较小;T4热处理试样表面出现较大的腐蚀坑;T6热处理试样的表面腐蚀坑大小及深浅不一,腐蚀最严重。极化曲线结果表明,SLM试样的腐蚀电流密度Jcorr最小,为(1.889±0.2)×10^(–5)A/cm^(2),耐蚀性能最好;固溶+时效处理2 h的试样Jcorr最大,为(1.225±0.2)×10^(–4)A/cm^(2),耐蚀性能最差。不同热处理试样的耐蚀性能优劣排序为:SLM试样>T4试样>T6试样。结论未经热处理的SLM试样晶粒尺寸最小,耐蚀性最好。经420℃保温6 h固溶处理后,β-Mg17Al12相基本溶解,晶粒尺寸增大1个数量级;加热至200℃时效2 h处理后,耐蚀性最差,当时效时间继续延长至6 h后,β-Mg17Al12相的数量逐渐增多,耐蚀性能反而有所增强。

关键词： 高强镁合金   挤压温度   显微组织   力学性能   Mg-8Sn-1M镁合金  

摘要： 对建筑用Mg-8Sn-1Mn高强镁合金进行了挤压试验,并进行了不同挤压温度下镁合金的显微组织和力学性能的测试与分析。结果表明:随着挤压温度的升高,Mg-8Sn-1Mn高强镁合金试样的抗拉强度和屈服强度先增大后减小,断后伸长率和平均晶粒尺寸先减小后增大。与300℃挤压相比,390℃挤压温度下试样的抗拉强度、屈服强度增大,平均晶粒尺寸减小。

关键词： 海水淡化装置   轻金属材料   体育用品   医疗器械   国防军工   制药领域   石油化工   生物相容性  

摘要： 钛及钛合金由于具有很高的强度和耐蚀性,已成为一种新兴的轻金属材料,并在国防军工、石油化工、制药领域及医疗器械、海水淡化装置等方面得到广泛应用。并且,因其具有比强度高、耐高温、导热率低、无毒、生物相容性好等一系列优点而被应用于航空、航天、建筑、体育用品等军用和民用领域。

关键词： 植入人工骨   椎体成型术   骨质疏松   骨折  

摘要： 目的:比较植入人工骨和椎体成型术治疗老年骨质疏松性骨折的临床效果。方法:选取2018年6月-2019年6月玉林市中西医结合骨科医院接诊的80例骨质疏松性骨折患者,采用交替分组法分为两组,实施不同手术方案,对照组40例行椎体成型术,试验组40例行植入人工骨手术,分析疗效。结果:术后1 d,两组骨代谢水平对比无统计学意义(P>0.05)。术后3个月,两组BALP水平对比差异无统计学意义(P>0.05);试验组BGP水平高于对照组(P<0.05)。术后3个月,试验组骨密度高于对照组(P<0.05)。试验组临床总有效率97.50%,高于对照组的85.00%(P<0.05)。试验组骨折愈合时间(16.01±1.12)周,较对照组短(P<0.05)。试验组术后6 h疼痛评分低于对照组(P<0.05)。试验组术后3、6、12个月疼痛再次发生率低于对照组(P<0.05)。结论:与椎体成型术治疗对比,植入人工骨治疗老年骨质疏松性骨折疗效更加显著,有助于缩短骨折愈合时间,促进骨折恢复,对于骨代谢具有一定积极意义。

关键词： Magnesium alloy   Strain rate   Fractograph   Hopkinson bar system   Scanning electron microscope   Material model  

摘要： The performance of a structure depends on its material characteristics under various conditions of loadings, strain rate, and temperature, and therefore, it is necessary to understand these characteristics properly for the safe and reliable design of structures. In this paper, the flow stress behavior of AZ81 magnesium alloy is determined under tensile, compressive, and flexural loads at different strain rates and temperatures. An electromechanical universal testing machine of capacity 250 kN is used to perform quasi-static tests (0.0001-0.1 s(-1)) under tension and compression;and three-point bending (flexure) tests using suitable fixtures at crosshead speeds (1-100 mm/min) for varying span lengths (80-160 mm) and orientations (flat and transverse) at room temperature, 25 degrees C. The thermal and fracture behaviors of the alloy at various temperatures (25 degrees C, 100 degrees C, 150 degrees C, and 200 degrees C) are studied under quasi-static tension (0.001 s(-1)). The heating rate of the tensile specimens is 20 degrees C/min and the soaking time is 15 min. Dynamic tensile (850-1,400 s(-1)) and compressive (1,900-3,300 s(-1)) experiments are conducted using appropriate arrangements of Hopkinson bar systems. The effects of specimen geometry on the flow stress of the alloy are observed under compression. Ductility and toughness are determined to establish the energy dissipation capacity of the alloy. Fractographs of the fractured tensile specimens are studied by scanning electron microscope (SEM). Also, the applicability of the existing Cowper-Symonds and Johnson-Cook models in the aforementioned loading conditions is discussed. (C) 2020 American Society of Civil Engineers.