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微量稀土Nd对AZ91微观组织及腐蚀性能的影响 总被引:1,自引:0,他引:1
采用X-射线衍射(XRD)、扫描电镜(sEM)、能谱分析(EDS)、集气法、动电位极化及浸泡实验等手段和方法研究了添加微量稀土元素钕(Nd)对AZ91镁合金微观组织及耐蚀性的影响,并从热力学角度分析了Nd对提高合金耐蚀性的影响机制.结果表明.少量稀土Nd细化了合金的微观组织,使β-Mg17Al12相变得断续、弥散,生成了Al3Nd相及Mg-Al-Mn-Nd-Fe金属问化合物;稀土Nd使合金在3.5%NaCl溶液中的自腐蚀电位升高,且与Al、O生成了不连续的致密的氧化膜,提高了合金的耐腐蚀性能;添加1.0wt%Nd时合金的耐蚀性最佳,腐蚀速率为0.28 mg·cm-2·d-1,比AZ91合金下降了一个数量级. 相似文献
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Mg-6Al镁合金具有较好的铸造性能和力学性能,目前鲜见单一稀土元素对其腐蚀性能影响的报道。通过合金制备、微观组织分析和耐蚀性测试等方法研究了稀土Gd添加量对Mg-6Al镁合金微观组织和耐蚀性能的影响。OM、SEM、EDS、XRD分析结果表明,稀土Gd的添加改善并细化了Mg-6Al合金的铸态组织,形成杆状或块状的Al2Gd新相;动电位极化、浸泡试验等测试结果表明Gd的添加显著提高了Mg-6Al合金在3.5%NaCl溶液中的耐腐蚀性能,Mg-6Al-2%Gd镁合金的腐蚀速度最小,为0.83 mm/a,且腐蚀后组织较为致密,腐蚀产物和腐蚀坑均变小,Mg-6Al-x Gd合金的腐蚀产物主要为Mg(OH)2。 相似文献
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研究了在变形镁合金AZ31中添加稀土元素Gd对合金铸态和轧态组织与性能的影响。结果表明:加入AZ31中的Gd元素形成了稀土相Al2Gd和Al-Mn-Gd的混合相,使β-Mg17Al12相的数量减少甚至消失。铸态合金中的少量Gd元素削弱了Al的晶粒细化作用,使组织粗化;而当Gd元素的含量提高时Gd开始发挥晶粒细化作用,使合金的晶粒显著细化。对于轧态合金,加入Gd元素后形成的Al2Gd相能促进合金在轧制过程中的动态再结晶,使孪晶数量减少,加工硬化作用减弱,晶粒尺寸细化。而过量的Gd元素形成粗大的第二相,使合金组织粗化。因此,适量的Gd元素可使轧态AZ31合金的强度降低而延伸率提高,其中在350℃轧制的AZ31-0.8Gd合金的延伸率最高(为13.4%),不含Gd的合金延伸率仅为5.4%。 相似文献
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不同表面处理工艺压铸镁合金涂层耐蚀性研究 总被引:3,自引:0,他引:3
为了研究不同表面处理工艺下压铸镁合金涂层的抗腐蚀性能,通过浸泡腐蚀和电化学腐蚀的方法,比较了微弧氧化和无铬化学氧化等表面处理试样的耐蚀性.结果表明,无铬化学氧化和微弧氧化处理能显著提高镁合金表面耐蚀性,而以微弧氧化处理更优;且两种处理方法覆盖层对孔洞、裂纹不敏感.根据交流阻抗图谱,拟合得到了微弧氧化、无铬化学氧化和未处理三种试样电化学腐蚀时体系的等效电路,拟合结果与实测结果吻合.XRD分析表明这两种处理方法得到的覆盖层中主体相均为Mg3Al2Si3O12等含硅的尖晶石型氧化物和Mg0.36Al2.44O4、MgAl2O4等不含硅的镁、铝复合氧化物,有利于提高镁合金耐蚀性. 相似文献
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本文研究了添加稀土元素 La、混合稀土(R·E)及钛元素对 Zn-27Al 合金耐蚀性能的影响,用扫描电镜观察了添加这些元素后合金中出现的化合物相,初步分析了这些化合物的形成过程及其对合金性能的影响。同时本文还探讨了热处理工艺改善 Zn-27Al 合金耐蚀性的可行性,讨论了添加元素—合金组织—相变—耐蚀性之间的关系。 相似文献
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Ni-α-Al2O3纳米复合电镀工艺的优选及镀层的硬度和耐蚀性 总被引:1,自引:0,他引:1
为了提高Ni-Al2O3纳米复合电镀层的硬度和耐蚀性,以正交试验对镀液温度、电流密度、α-Al2O3纳米粒子质量浓度等因素进行了优选,采用扫描电镜、能谱仪、硬度仪及电化学工作站分别研究了镀层的微观形貌、能谱、硬度和耐蚀性。获得了最优工艺条件:镀液温度65℃,阴极电流密度2 A/dm2,Al2O3加入量为10g/L;在此工艺条件下所得Ni-α-Al2O3纳米复合镀层晶粒细小、表面平整、光滑,显微组织致密、均匀,镀层的硬度及耐蚀性比纯镍镀层均有显著提高。 相似文献
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镁合金废料的回收及熔炼技术的研究 总被引:1,自引:0,他引:1
镁合金材料在运输工具、3C产品等领域的用量日益增长,随之而来的废镁量也越来越多.为了保护环境、对废料的再生利用,需要寻求一种经济的、质量能得到保证的再生利用技术.结合实际从废镁合金的产生、废镁合金的分类、镁合金废料的前期处理、镁合金的熔炼方法等方面分别进行了阐述. 相似文献
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Mechanoelectrochemical Behavior of Pure Magnesium and Magnesium Alloys Stressed in Aqueous Solutions 总被引:1,自引:0,他引:1
E. M. Gutman Ya. Unigovski A. Eliezer E. Abramov 《Journal of Materials Synthesis and Processing》2000,8(3-4):133-138
A new synergistic effect of corrosion and stress on the viscoelasticity of pure magnesium and magnesium alloys has been shown. This phenomenon named corrosion creep has been studied in 99.9653% Mg, die-cast AZ91D (Mg–9% Al–1% Zn), AM50 (Mg–5% Al–0.4% Mn), and AS21 (Mg–2.3% Al, 0.23% Mn, 1.10% Si) alloys. Creep tests were carried out at 25°C in air and in the borate buffer aqueous solution (pH 9.3). It is found that the highest sensitivity to creep in the corrosive environment is observed in the alloy with the highest Al content. This agrees with the data obtained earlier in the study of mechanoelectrochemical behavior and corrosion fatigue of Mg alloys. However, in air, the creep behavior of all alloys at room temperature is approximately the same. Creep life of pure magnesium and its alloys significantly decreases in a corrosive environment. Corrosion-creep cracks filled with magnesium hydroxide particles were observed by SEM–EDS analysis at the surface of AS21 alloy. The thickness of the oxide layer defined by AES in samples of AZ91D, AM50, and AS21 alloys placed for 2 h into the borate solution amounts to 540, 1320, and 1440 nm, respectively. This can be explained with the account for surface phenomena. 相似文献
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Magnesium oxychloride cement concrete 总被引:1,自引:0,他引:1
The scope of magnesium oxychloride (MOC) cement in concrete works has been evaluated. MOC cement concrete compositions of
varying strengths having good placing and finishing characteristics were prepared and investigated for their compressive and
flexural strengths, E-values, abrasion resistance etc. The durability of MOC concrete compositions against extreme environmental conditions viz.
heating-cooling, freezing-thawing, wetting-drying and penetration and deposition of salts etc were investigated. The results
reveal that MOC concrete has high compressive strength associated with high flexural strength and the ratio of compressive
to flexural strength varies between 6 and 8. The elastic moduli of the compositions studied are found to be 23–85 GPa and
the abrasion losses between 0·11 and 0·20%. While alternate heating-cooling cycles have no adverse effect on MOC concrete,
it can be made durable against freezing-thawing and the excessive exposure to water and salt attack by replacing 10% magnesium
chloride solution by magnesium sulphate solution of the same concentration. 相似文献