New Thermodynamic Data for Liquid Aluminum-Magnesium Alloys from emf,Vapor Pressures,and Calorimetric Studies

Experimental thermodynamic studies of liquid Al-Mg alloys have been performed by several methods resulting in: (1) Mg activities from galvanic cells with liquid electrolytes at temperatures from 910 to 1070 K, at X_Mg = 0.1 to 0.7 and for the dilute range when X_Mg = 0.0126 to 0.1430 at 927 K; (2) Mg activities from the emf method with solid CaF2 electrolyte at temperatures 921 to 1093 K, with concentrations XMg = 0.05 to 0.9; (3) Mg activities from vapor pressure measurements (Knudsen effusion method) at temperatures ranging from 722 to 1188 K, at X_Mg = 0.0424 to 0.8885. Vapor pressures of pure solid Mg at temperatures 674 to 851 K. In addition, liquidus temperatures for Mg- and Al-rich alloys were obtained; and (4) Partial and integral enthalpies from reaction calorimetry at 1023 K, starting from pure Mg bath at concentrations, X_Al = 0.066 to 0.499, and starting from pure Al bath at X_Mg = 0.522 to 0.906. The mutual consistency of these four sets of data was analyzed. New results together with the selected thermodynamic information reported in literature were optimized to describe the liquid phase with the Redlich-Kister equation, as a preliminary step for phase diagram calculations of the Al-Mg system.     

Vapor Species Over Te Precious Metal Minerals

This paper reports on two developments of interest to extractive metallurgists: how the knowledge of the vapors over tellurium minerals can be used to develop better processing methods and how graphite furnace atomic absorption, used at moderate temperatures, can be used to characterize the vapors over ore minerals. Elemental tellurium, Ag₂Te, and AuTe₂ were studied from 250°C through 1050°C. The vapors over these solids were analyzed in-situ by placing the solids directly into the graphite furnace of an atomic absorption spectrophotometer and adjusting the temperature accordingly. Atomic Ag, Au, and Te and molecular Te were analyzed in the vapor above the solids. Using absorbance versus temperature data, Clausius-Clapeyron plots were made to determine how the solids were changing.     

锌铝合金的研究进展

回顾了锌铝合金的发展历史，介绍了锌铝舍金的成分、组织及性能特点，重点详述了舍金元素的作用和变质处理工艺。     

The Electrodeposition of Zinc on Aluminium and Its Alloys

Dull nickel deposits may be given a brilliant finish by a brief anodic treatment in a sulphuric acid solution; polishing action is obtained over a wide range of conditions. The method has possibilities as an alternative to bright nickel plating and the process has been investigated from this point of view. Under suitable conditions, the process does not adversely affect the protective properties of the deposit and the quality of the finish is at least as good as that obtained by bright nickel plating. The method also enables designs to be formed on nickel surfaces by localising the area polished, and attractive finishes may be produced in this way.     

生物可降解锌合金用于骨植入物的研究进展

生物可降解锌合金是新型的具有发展前景的人体骨植入物材料。讨论了生物可降解锌合金在力学性能、腐蚀降解行为和生物相容性等方面作为骨植入物材料的开发潜力和应用前景。重点综述了近年来不同合金元素的选择和添加量对生物可降解锌合金的强韧化影响、生物可降解性及生物相容性评价。同时,讨论了塑性变形过程对生物可降解锌合金力学性能的影响。另外,还介绍了生物可降解锌合金的体内外降解行为、生物腐蚀机理、生物相容性及其要求。明确了各种增强手段对生物可降解锌合金的影响,并分析讨论了各种手段的可取与不足之处。针对当前制备技术存在的问题,结合已有研究成果,指明生物锌合金未来的发展方向。生物锌合金的强化方法,如合金化、改变添加量、变形加工操作、表面改性处理等,可以有效提高纯锌的综合性能。锌合金的降解速率适中,不产生氢气袋,降解产物能起到保护层的作用,有助于提高细胞黏附性,增强抗菌能力。锌合金的生物相容性与锌离子的释放量密切相关。制备ZnP涂层的表面改性技术能够有效降低锌离子释放量,进而改善生物相容性。目前,生物可降解锌合金在生物体植入物中已经取得部分进展,但是,其力学性能和生物相容性仍是较长一段时间内努力的方向,开发新的增强手段及体内动态模拟试验和性能评估方法也都是未来的重要发展趋势。     

三元合金高温理论氧化图Ⅱ.低氧压下的近似分析

在假设三元A-B-C固溶合金中三组元氧化物不互溶且不形成复合氧化物，并忽略合金内氧化的条件下，计算并建立了合金在单一氧化剂、低氧压下形成各氧化物的动力学氧化图，并考虑组元的扩散作用，描述了变氧压条件下该四元系合金与各氧化物之间的平衡关系以及合金的成膜规律。     

低蒸气压中温钎料研究进展

熔点在400～600℃的低蒸气压中温钎料在电子器件、电真空元件、硬质合金刀具等钎接领域的应用十分广泛.本文概述了中温钎料的最新研究现状,指出在Ag-Cu二元舍金中复合添加适量的Sn、In、Ni、Si、Ge和Ga元素进行合金化处理,是获得低蒸气压中温真空钎料的有效途径.     

锌基合金热力学和相图数据库的建立

利用Visual Basic 6.0软件开发了一套锌基合金体系热力学和相图数据库系统,用于收集、整理锌基合金体系的热力学和相图相关信息.利用该软件系统可以实现对锌基合金体系热力学和相图数据的排序、查询和打印等功能,也可实现数据库的实时更新.探讨了如何实现该软件系统的各项功能,解决了锌合金体系热力学和相图数据人工查询的低效率问题,该数据库软件在锌合金的改性和新型锌合金的设计与开发应用中具有一定使用价值.     

High-Strength Aluminum Alloys with Zinc,Magnesium, and Copper

Metal Science and Heat Treatment -     

Complete Kinetic Maps for Binary Alloys Forming Two Insoluble Oxides Under High Oxygen Pressures

The oxidation under high pressures of a single oxidant of binary A–B alloys forming two insoluble oxides involves the internal oxidation of the most reactive component B when its concentration falls below an upper critical concentration defined by means of a criterion due to Wagner. However, this oxidation mode is no longer stable for alloys sufficiently dilute in B. The paper predicts the nature of the oxidation modes stable in this alloy region and calculates the critical contents of B required for the corresponding transitions.     

环氧涂层中锌铬黄颜料对镁合金的防蚀机理

采用电化学阻抗、动电位极化、开路电位监测和X射线光电子能谱(XPS)等手段,研究了环氧涂层中锌铬黄颜料对镁合金的腐蚀防护作用,并分析了其防蚀机理。结果表明,锌铬黄防锈颜料均匀分散在涂层中,增强了涂层的屏蔽性能以及涂层与镁合金基体的结合力;在3%NaCl水溶液中,锌铬黄是一种阳极型缓蚀剂,它依靠铬酸根离子的阳极钝化作用形成钝化膜,阻滞了阳极腐蚀过程,造成涂层试样开路电位正移,使涂层试样的阳极极化增大。     

A356合金二次无氰浸锌层的微观组织研究

本文利用扫描电镜（SEM）和原子力显微镜（AFM）观察了一次浸锌和二次浸锌不同时间下浸锌层的微观形貌，建立了无氰多元浸锌全过程模型。结果表明铝及其合金的浸锌过程是锌晶粒在基体上不断形核和长大的过程。浸锌初期主要是晶核形成期，浸锌后期主要是晶粒生长期；金属离子放电的高活性中心在金属表面上的低能量点上，多元合金中的铁、镍和铜是锌晶粒生长的异质晶核；二次浸锌得到的锌晶粒比一次浸锌更细小、均匀和致密，对基体覆盖能力好。二次浸锌时间为20-30S时，浸锌层的微观形貌最好。     

电子束物理气相沉积TiAl基合金薄板的物相及显微分析

采用电子束物理气相沉积（EB-PVD）技术，成功制备了尺寸为150mm×100mm的TiAl基合金薄板，并利用光学显微镜（OM）、扫描电子显微镜（SEM）和x射线衍射（XRD）等测试手段，对真空退火或热压前后试样的显微形貌、物相组成等进行了分析。结果表明，蒸镀态TiAl基合金薄板由 γ相、α2相和ι相组成，成分呈梯度变化，内部自然分层，显微组织结构为柱状晶；经1000℃，16h的真空退火处理后，柱状晶和τ相消失，α2相含量显著减少，成分趋于均匀化；而经1250℃，1h的真空热压处理后，材料致密度得到明显提高。TiAl基合金薄板经真空退火或热压处理前后，断裂方式由沿晶断裂转变为解理断裂和沿晶断裂的混合断裂方式。     

硅对铁基合金耐液锌腐蚀的影响

采用扫描电镜(SEM)和能谱(EDS)分析对含硅和不含硅的铁基合金在450℃液锌中的腐蚀行为进行了研究。结果表明:在浸锌时间不长的情况下,不含硅的铁基合金的耐锌蚀能力较好,随着浸锌时间的延长,含硅的铁基合金表现出较好的耐锌蚀能力,基体中Si的加入,界面处液相中Si富集,使得ζ相生长方式接近线性生长,导致腐蚀产物中的ζ相呈粗大的柱状,且腐蚀层中Г相消失,ζ相优先在Fe-Zn界面形成。     

La对高铝锌合金组织和性能的影响

在高铝锌合金中加入不同量的稀土La浇注合金试样,通过微观金相组织分析和力学性能分析,研究了微量稀丰元素La对进一步改善锌铝合金组织、提高性能及作用机理.试验结果表明:La加入量在0.1%时,能够细化锌铝铸造合金的组织,改善高铝锌合金的力学性能,合金的拉伸强度、伸长率和硬度都有一定的提高;La的加入量过多时,La以块状的富La稀土相析出;La加入量在0.4%左右时,能够显著消除合金的底缩.     

Fe-Al-Cr合金在含锌蒸汽的低氧压中预氧化后的表面形貌

在900、950和1 000℃含Zn蒸汽的低氧压下对4种Fe-Al-Cr合金进行了预氧化实验,时间为1~5 h。Zn/Zn O粉末加热后提供的氧压在10-21~10-18 MPa之间。结果表明:经1 000℃预氧化1 h,Fe-1.2Al-2Cr合金表面的组织是Zn M2O4(M∶Al+Cr)+Zn O+α-Fe,Fe-2Al-3Cr及Fe-3Al-4Cr合金的表面组织是Zn M2O4+α-Fe,Fe-3Al-6Cr合金的组织是Zn M2O4+M2O3。合金中随Al、Cr元素少量的增加,表面氧化物增加,其中的Al含量快速增加;表面褶皱程度降低,突出的α-Fe相数量减少,向圆粒状转变。延长预氧化时间与提高预氧化温度都可以使表层的α-Fe相减少,氧化物面积增加。Zn在试样表面分布均匀,会渗入α-Fe相,会与表层的铝铬氧化物反应生成Zn M2O4相。     

Complete Maps for the Internal Oxidation of Ideal Ternary Alloys Forming Insoluble Oxides under High Oxidant Pressures

This paper presents an analysis of the conditions of stability of the different forms of internal oxidation of ideal ternary A-B-C alloys, where A is the most noble and C the most reactive component, forming insoluble oxide and exposed to high pressures of a single oxidant. The treatment, based on an extension to ternary alloys of Wagner's criterion for the transition from internal to external oxidation in binary alloys, allows to predict the existence of three different forms of internal oxidation. In fact, in addition to the most common kinds of internal attack, involving the coupled internal oxidation of B+C beneath external AO scales and the internal oxidation of C beneath external BO scales, a third mode, involving the internal oxidation of C beneath external scales composed of mixtures of AO+BO, becomes also possible under special conditions. A combination of the boundary conditions for the existence of these different types of internal oxidation allows to predict three different kinds of complete maps for the internal oxidation in these systems, one of which involves only two modes, while the other two involve all the three possible modes of internal oxidation.     

Effect of Zinc Chloride in Ash in Oxidation Kinetics of Ni-Based and Fe-Based Alloys

Corrosion by molten phases leads to severe corrosion of heat exchangers in waste-to-energy plants. In addition, the presence of heavy metal chlorides in ash deposit increases degradation at low temperature due to the formation of highly corrosive molten phases. In this study, two heat exchanger materials, a low alloy steel (16Mo3) and a nickel based alloy (Inconel 625) were exposed in air to three different synthetic ashes, with various chloride contents, including ZnCl₂ at isothermal temperatures of 450 and 650 °C in a muffle furnace. After the test, thickness and mass losses were evaluated on two separate samples, and metallographic cross sections of the specimens were characterized via SEM/EDX analyses. Both measurement results were in good agreement and showed that the corrosion observed on both materials was higher in the presence of zinc chloride in ash at 450 °C than in ashes without heavy metal chloride at 650 °C.