Effects of sodium tungstate on characteristics of microarc oxidation coatings formed on magnesium alloy in silicate-KOH electrolyte

Oxide coatings on AM60B magnesium alloy were prepared using the microarc oxidation（MAO） technique in silicate-KOH electrolyte with addition of 0-6.0 g/L Na2WO4. The MAO processes in base electrolyte with different concentrations of Na2WO4 were studied. The microstructure, compositions and mechanical tribological characteristics of the oxide coatings were also investigated by SEM, XRD, XPS, microhardness analysis and ball-on-disc friction testing, respectively. It is found that the addition of Na2WO4 into the base electrolyte has direct effect on the characteristics of voltage-time curves and breakdown voltage in MAO process. The number of micropores at top of the coating surface is increased by the addition of Na2WO4. The fraction of forsterite Mg2SiO4 in the oxide coating increases with increasing concentration of Na2WO4 in base electrolytes. Furthermore, the microhardness and wear resistance of oxide coatings are enhanced as well.     

Microstructure and properties of cutting magnesium-brass containing no lead

1 INTRODUCTIONLead-brass has excellent cutting ability , me-chanical and physical properties and is one of themost widely used copper alloys . The occupationratio of brass tube to all kinds of tubes reaches90 % in developed countries . The cutting lead-brass is a dual-phase brass and fine lead particlesdistribute dispersivelyin grains and on grain boun-ries . Theleadin wasted brass can easily beleachedand dissolvedinto soil .If the wasted lead-brass isburned in air ,the lead will become p…     

镁合金材料的应用及其加工技术的发展(1)

第一部分较全面地介绍镁及镁合金材料在交通运输、航空航天、电子工业、核能工业、化工、冶金等部门的应用方向与实例。第二部分简要地论述镁合金材料的加工技术，重点介绍镁合金新材料的研发、熔炼铸造工艺、压铸成型工艺、挤压技术、锻压技术与轧制技术的进展。指出镁合金是一种很有发展前景的新型金属材料，其加工技术将获得进一步的快速发展。     

PHASE INTERFACE SEGREGATION OF Mg IN A Ni-BASE SUPERALLOY IN100

The segregation of Mg to phase interfaces in a nickel base superalloy IN 100 has been investi-gated using EPT(Electron Microprobe Technique).AES(Auger Electron Spectroscopy)and EDS analyses on thin TEM film.The results show that Mg segregates to the phase inter-faces of MC/γ and γ′/γ.The segregation concentration and layer thickness of Mg onMC/γ phase interface are larger than that on γ′/γ phase interface.Mg is not only a grainboundary segregation element,but also a phase interface segregation one.     

高温镁合金的成分、组织设计与制备加工技术进展

介绍了提高镁合金高温性能的主要途径及目前研究较多的Mg-Al系、Mg-Zn系和Mg-RE系合金,同时分析了正在开始研究的含Y、Sc、Gd等稀土的新型耐热镁合金;同时分析了耐热合金中的耐热相,耐热合金的加工制备工艺进展。     

合金化对AZ91D镁合金组织与力学性能的影响

利用光学显微镜（OM）和X射线衍射（XRD）分析了分别加入合金化元素Ce，Si和Ca后AZ91D合金的铸态组织和相组成，测试了合金室温拉伸性能和硬度。结果表明：加入Ce和Si后合金组织中分别生成杆状Al4Ce和汉字状Mg2Si相，而加入Ca后无新相生成，加入的Ca主要固溶于β相中；Al4Ce和Mg2Si相在合金凝固过程中被推移到生长界面，Ca原子偏聚在生长界面前沿，从而阻碍枝晶的自由生长，细化合金铸态组织：Ce和Ca的加入可提高合金室温综合力学性能，且前者提高程度要高于后者提高程度，而Si的加入却降低合金室温综合力学性能。     

镁合金结构及焊接

从战略高度阐明了研发镁合金结构材料的重要意义和它在汽车、国防军工、电子产品、民用产品的应用现状,并将其与高分子材料进行了比较.讨论了研发镁合金所需解决的问题以及镁合金的可焊性,介绍了镁合金焊接的新成果.     

AZ91D镁合金化学镀镍

利用化学镀镍的方法，在AZ91D镁合金表面得到了均匀、致密，无明显表面缺陷的Ni－P涂层，X－ray衍射分析表明，镀层组织为单一的Ni；热震实验表明涂层与基体合金结合良好；动电位极化测试表明涂层的自腐蚀电位接近－0．4V（SCE），有明显的钝化区，而腐蚀性能优异，可对基体合金起到理想的防护作用。     

镁合金TIG焊工艺

分析了镁合金的焊接特点和焊接性,指出了目前镁合金熔化焊接时的难点.针对镁合金的TIG焊方法,从焊缝组织、极性选择、氩气流量以及工艺参数、缺陷修复等方面做了全面阐述.指出了镁合金TIG焊的不足之处和研究重点.     

HOMOGENIZATION TREATMENT OF Mg-Al-Zn(MM)MAGNESIUM ALLOY INGOTS

The Mg-Al-Zn series AZ31 and AZ31 MM alloys are homogenized at 673, 723 and 753K respectively. The hardness of alloy ingots at different heat-treated states is measured and the micro structures are observed. The optimum annealing temperature is 723K and the time is 12h.