Compression Properties of Ti-Al-X Alloys in Relation to Site Occupancies of Alloying Elements in TiAl and Ti3Al

1-IntroductionGammaTiAla1loyswithpotelltialforengineer-ingapplicationsinvariablycofltainasmallamountofa2-Ti3Alphase.Severalrepresentativetypesofmi-crostructurecanbeobtainedthroughbothalloyingandprocessing,resultinginsignificantvariationinmechanicalproperties[1].Extensiveresearchinthelastdecadehasbeendirectedatfindingthecorre-lationbetweenthemicrostructuralparametersandproperties;theunderstandingofthefundamentalmechanismofalloyinghasreceivedlessattention.Theimportanceofthislatterissueisbestil…     

Sb,Bi 元素对 Sn-22 Sb 高温钎料合金组织的影响

目的研究Sb和Bi元素对Sn-22Sb钎料显微组织的影响。方法制备了(Sn-22Sb)-xBi和Sn-xSb钎料合金,并分别采用差热分析和X射线衍射仪,分析了材料的熔化特征和物相。结果结果表明:Sn-22Sb钎料合金主要由灰色的β-Sn和白色块状的Sb2Sn3构成;少量的Bi使得Sn-22Sb钎料合金中Sb2Sn3金属间化合物逐渐细化和均匀化,数量却急剧增加;大量添加Sb后,使得Sn-22Sb钎料合金几乎全部变为粗大的块状β-SnSb组织,钎料合金的开始熔化温度有所提高。结论通过添加其他合金元素,降低Sn-50Sb钎料液相线温度,使其有望应用于二次回流焊。     

Mg-Al系耐热镁合金中的合金元素及其作用

合金化或微合金化作为改善合金性能或设计新型合金的重要手段之一,目前已普遍应用于Mg-A1系耐热镁合金的研究开发中.综述了Mg-Al系耐热镁合金中合金元素Al、Zn、Mn、Sb、Bi、Sn、Si、RE、Ca和Sr的作用行为,重点分析了Al和Zn 2种主体元素对Mg-Al系耐热镁合金组织和性能的影响,讨论了合金元素使用中存在的问题和今后的发展方向.     

Influence of alloying elements on temperature and composition for peritectic reaction in plain carbon steels

Abstract

The temperature and composition for the peritectic reaction have been evaluated thermodynamically for Fe–C-base ternary alloys containing a small amount of the third element. The peritectic temperature is significantly reduced by alloying elements having a strong tendency to segregation, such as sulphur and phosphorus, which are characterized by small coefficients of partition between solid and liquid. The effect of an alloying element on the temperature and composition for the peritectic reaction relates to the atomic number of the element. Alloying elements with larger or smaller atomic numbers in a periodic row have a significant influence on the peritectic temperature. The liquidus and solidus temperatures of plain carbon steels were also evaluated; the solidus temperature showed an explicit linear relationship with the ductile–brittle transition temperature of the steels.

MST/342     

Structure,mechanical properties,corrosion behavior and cytotoxicity of biodegradable Mg–X (X = Sn,Ga, In) alloys

As-cast Mg–Sn, Mg–Ga and Mg–In alloys containing 1–7 wt.% of alloying elements were studied in this work. Structural and chemical analysis of the alloys was performed by using light and scanning electron microscopy, energy dispersive spectrometry, x-ray diffraction, x-ray photoelectron spectroscopy and glow discharge spectrometry. Mechanical properties were determined by Vickers hardness measurements and tensile testing. Corrosion behavior in a simulated physiological solution (9 g/l NaCl) was studied by immersion tests and potentiodynamic measurements. The cytotoxicity effect of the alloys on human osteosarcoma cells (U-2 OS) was determined by an indirect contact assay. Structural investigation revealed the dendritic morphology of the as-cast alloys with the presence of secondary eutectic phases in the Mg–Sn and Mg–Ga alloys. All the alloying elements showed hardening and strengthening effects on magnesium. This effect was the most pronounced in the case of Ga. All the alloying elements at low concentrations of approximately 1 wt.% were also shown to positively affect the corrosion resistance of Mg. But at higher concentrations of Ga and Sn the corrosion resistance worsened due to galvanic effects of secondary phases. Cytotoxicity tests indicated that Ga had the lowest toxicity, followed by Sn. The most severe toxicity was observed in the case of In.     

Sn对镁及镁合金显微组织和性能影响的研究现状及展望

合金化元素Sn在镁基体中的固溶度受温度影响比较大,且能够与镁形成高强、高硬、热稳定性好的Mg2Sn金属间化合物,在理论研究和实际应用上引起了人们的广泛关注。基于Mg、Mg-Al-Zn系、Mg-Mn系、Mg-Zn系、Mg-Li系等合金,综述了Sn对纯镁及镁合金微观组织及力学性能的影响,概述了Sn对镁合金的腐蚀、电化学等其他性能的影响。最后展望了Sn在镁合金中的应用前景。     

合金元素对镁合金耐腐蚀性能影响的研究进展

添加合金元素即合金化是改善镁合金性质、性能的有效途径。总结了基础合金元素(Al、Zn、Mn、Zr等)和微量合金元素(Ce、La、Sc、Er、Nd、Y、Sm、Ho、Gd及混合稀土等稀土元素和Ca、Sr等碱土金属元素以及Pb、Sn、Sb、Si、Hg、Ga等)对合金化镁合金耐腐蚀性能的影响,评述了失重法、电化学方法等合金化镁合金耐腐蚀性能的主要研究方法,指出了当前镁合金合金化及耐腐蚀性能研究中存在的问题和发展方向。     

Variations of color with alloying elements in Pd-free Au–Pt-based high noble dental alloys

The effects of alloying addition of a small amount of base metals (In, Sn, Fe, Zn) on color variations in Pd-free Au–Pt-based high noble dental alloys were investigated in terms of rectilinear and polar color coordinates. The ternary Au–Pt–X (X = In, Sn, Fe, Zn) and quaternary Au–Pt–In–Y (Y = Sn, Fe, Zn) alloys were prepared from high purity component metals. The amount of alloying base metals, X and Y, were restricted up to 2 at.%. The alloying addition of a small amount of Fe, In, Sn, to a binary Au–10 at.% Pt alloy (referred to as AP10) effectively increased chroma, C^*. On the other hand, the addition of Zn to the parent alloy AP10 did not change color coordinates greatly. The increase in chroma in the present Au–Pt-based high noble alloys was attributed to the increase in the slope of spectral reflectance curve at its absorption edge near 515 nm. It was found that the addition of a small amount of Fe to the parent alloy AP10 markedly increased lightness, L^*, and the addition of Sn gave a very light tint of red to the parent alloy. Although red–green chromaticity index a^* contributed to chroma to some extent, contribution of yellow–blue chromaticity index b^* was much greater in determining chroma in this Pd-free Au–Pt-based multi-component alloys. The present results are expected to be valuable in case color is to be taken into account in designing Pd-free Au–Pt-based high noble dental alloys.     

Evolution of alloying elements during outgassing in an aluminium zinc magnesium alloy made by powder metallurgy

To obtain high-quality produces from aluminium alloys powders, degassing is usually carried out before consolidation. But, in the case of Al-Zn-Mg alloys an evaporation of alloying elements may occur during outgassing. The aim of this work was to determine the influence of degassing conditions (temperature, pressure, nature of the gaseous atmosphere) on the stability of the alloy composition. These studies were performed on X7091 alloy by means of thermogravimetry and temperature-programmed desorption technique. The results show that liberation of alloying elements is closely connected with the evolution of the surface oxide layer which itself depends on various thermodynamic and kinetic parameters. The role of water vapour in the gaseous environment was particularly emphasized.     

The relation between valency,axial ratio,Young’s modulus and resistivity of rapidly solidified tin-based eutectic alloys

Eutectic alloys of Sn with Cu, Cd, Al, Pb and Sb (peritectic) were produced by the melt-spinning technique. These alloying elements were chosen according to their valencies +1, +2, +3, +4 and +5 respectively. X-ray diffraction analysis (XRD) was carried out. Young’s modulus and resistivity were measured. It was found that, alloying Sn with low valency metals such as Cu and Cd increases the axial ratio and alloying Sn with high valency metals such as Pb, Sb and Bi decreases the axial ratio. Also Young’s modulus was found to increase by increasing the axial ratio and decreases by decreasing it. On the contrary the resistivity decreases by increasing the axial ratio.     

The effects of third alloying elements on the bulk Ag<Subscript>3</Subscript>Sn formation in slowly cooled Sn–3.5Ag lead-free solder

The effects of third alloying elements (Cu, In, Zn) on the formation of bulk Ag₃Sn intermetallic compounds (IMCs) in slowly cooled Sn–3.5Ag lead-free solder were investigated by microstructural observation and thermal analysis technique. Microstructural observation shows that bulk Ag₃Sn IMCs existed in the microstructure of slowly cooled Sn–3.5Ag, Sn–3.5Ag–0.75Cu and Sn–3.5Ag–1.5In alloys, while no bulk Ag₃Sn IMCs formed in the slowly cooled Sn–3.5Ag–2.0Zn alloys. Thermal analysis results indicate that Ag preferably reacted with Zn to form Ag–Zn IMCs at high temperature rather than reacted with Sn to form Ag₃Sn plate.     

Effect of Ru on microstructural evolution during heat treatment in single crystal superalloys

Abstract

The effect of Ru addition on the as cast microstructure, structural evolution during heat treatment and long term aging was employed in single crystal superalloys with different contents of Ru addition (0, 1·5 and 3·0 wt-%). The results show that NiAl based β phase can occur in the interdendritic region in 3Ru alloy. With increasing Ru content in the alloys, the incipient melting temperature of alloy decreases gradually, while the liquidus and solidus changed slightly. After solution treatment and the same aging treatment, the γ′ phase size decreased with increasing Ru addition. An remarkable inverse partition of alloying elements, i.e. more matrix forming elements Re and Mo distribute to the γ′ phase and more Ni element distribute to the matrix, was observed in the alloys with more Ru content after aging treatment. Ru addition can accelerate the rafting of γ′ phase and suppress the precipitation of topologically close packed (TCP) phases effectively.     

Design of lead-free candidate alloys for low-temperature soldering applications based on the hypoeutectic Sn–6.5Zn alloy

The coupling effect of both minor alloying addition and reducing the amount of Zn phase have been proposed as an important strategy to improve the integrity and reliability of eutectic Sn–9Zn solder joints. In this work, the changes in microstructures, thermal behaviors and mechanical properties associated with the alloying of Ni and Sb to eutectic Sn–Zn after reducing the amount of Zn phase were explored. Thermal analysis confirmed that Ni and Sb additions being effective in reducing the amount of undercooling, while the melting temperature and pasty range remained at the hypoeutectic Sn–6.5Zn level. The resulting ultimate (UTS), yield tensile strength (YS) and elongation (El) of Sn–6.5Zn–0.5Ni and Sn–6.5Zn–0.5Sb alloys were experimentally determined and compared with the corresponding results of plain Sn–6.5Zn solder alloy. It was found that the Sn–6.5Zn–0.5Ni and Sn–6.5Zn–0.5Sb alloys examined comply with the compromise between high mechanical strength and ductility. Microstructural analysis revealed that the origin of change in mechanical properties was attributed to the enhanced solid solution effect of Sb and the flower shaped (Ni, Zn)₃Sn₄ intermetallics (IMC) phase produced by Ni addition. The Sn–6.5Zn–0.5Sb alloy has the highest UTS and appropriate ductility of all alloys examined. This finding indicates the capability of newly developed ternary solder alloys to serve a much wider array of value-added applications.     

Development and characterization of β-type Ti-Zr-Nb-Sn dental implant materials

To develop new materials of proper elastic modulus and biocompatibility for dental implants, Ti-2Zr-xNb-xSn (x = 0, 0.1, 0.2, 0.3) and Ti-2Zr-xNb-xMo (x = 0, 0.1, 0.2, 0.3) alloys were designed and fabricated. Effects of alloying elements on properties and the feasibility of application in dentistry are analyzed. It is indicated that Nb, Sn and Mo obviously influence the phase compositions of Ti-2Zr-based biological alloys. With the increase of alloying element content, all the alloys tend to form a single β-Ti phase. Ti-2Zr-xNb-xSn alloys exhibit better mechanical properties and corrosion resistance than the Ti-2Zr-xNb-xMo alloys. The Ti-2Zr-0.1Nb-0.1Sn alloy has proper elastic modulus (14.72 GPa) (which is very close to the natural bones), excellent corrosion resistance and comprehensive mechanical properties, and is considered as ideal candidate for implant materials.     

国内Spinodal分解Cu-Ni-Sn系合金研究进展

全面回顾了国内自开展Spinodal分解Cu-Ni-Sn系合金研究以来所做的工作,系统介绍了Cu-Ni-Sn系合金的组织、性能、添加元素的作用以及制备方法,并指出进一步提高合金性能、开发能抑制Sn偏析的合金制备新技术是今后研究的方向.     

Design of lead-free candidate alloys for high-temperature soldering based on the Au–Sn system

Au–Sn based candidate alloys have been proposed as a substitute for high-lead content solders that are currently being used for high-temperature soldering. The changes in microstructure and microhardness associated with the alloying of Ag and Cu to the Au rich side as well to the Sn rich side of the Au–Sn binary system were explored in this work. Furthermore, the effects of thermal aging on the microstructure and microhardness of these promising Au–Sn based ternary alloys were investigated. For this purpose, the candidate alloys were aged at a lower temperature, 150 °C for up to 1 week and compared with aging at 200 °C for respective durations. It was determined in this work that the candidate alloys on the Sn rich side were relatively more stable, i.e. only the aging temperature had a substantial impact on the microstructure and not the aging duration. The candidate alloys aged at 200 °C were substantially softer on the Au rich side than the candidate alloys on the Sn rich side. However, the difference in hardness narrowed down considerably between the candidate alloys on the Au rich side and the Sn rich side when subjected to aging at 150 °C.     

Influence of alloying elements on thermal conductivity and high temperature strength of copper based alloys

Abstract

The effects of alloying elements and annealing temperature on thermal conductivity and softening behaviour of Cu – 0·1Ag – xP–yMg and Cu – xSn – yTe alloys (all compositions are in wt-%) have been investigated. The Cu – 0·1Ag – xP–yMg alloys, in spite of greater amounts of P and Mg, had a higher electrical conductivity and a higher softening temperature than those of a Cu – 0·1Ag – 0·031P alloy. A Cu – 0·032Sn – 0·023Te alloy had the same levels of electrical conductivity and softening temperature as those of Cu – 0·040Sn. The conductivity and softening temperature of the Cu – 0·032Sn – 0·023Te alloy are comparable with those of the Cu – 0·1Ag – 0·013P alloy currently used for continuous casting mould materials.     

Modelling beta transus temperature of titanium alloys using artificial neural network

An artificial neural network (ANN) model is developed to simulate the non-linear relationship between the beta transus (β_tr) temperature of titanium alloys and the alloy chemistry. The input parameters to the model consist of the concentration of nine elements, i.e. Al, Cr, Fe, Mo, Sn, Si, V, Zr and O, whereas the model output is the β_tr temperature. Good performance of the ANN model was achieved. The interactions between the alloying elements were estimated based on the obtained ANN model. The results showed good agreement with experimental data. The influence of the database scale on ANN model performance was also discussed. Estimation of β_tr temperature through thermodynamic calculation was carried out as a comparison.     

Metallurgical structure and phase diagram of Fe–C–V system: comparison with other systems forming MC carbides

Abstract

Liquid–solid equilibria were studied in the Fe rich corner of the Fe–C–V system using differential thermal analysis (DTA), SEM, TEM, and electron probe microanalysis. A modified version of the DTA technique, quenched interrupted DTA, was employed to establish the solidification paths. Several transformations occurring just below the liquidus temperature are described and explained by reference to the peritectic reaction and a proposed metatectic transformation. The tie lines were determined at the liquidus temperature and an equation is proposed to predict the partitioning coefficient of V as a function of the composition of the alloy. The influence of other solute elements on the equilibria and on the microstructure was investigated. A comparison is drawn with some similar systems: Fe–Nb–C, Fe–Ta–C, and Fe–Ti–C. In particular, for all these systems, blocky, faceted carbides form in the melt even in hypoeutectic alloys.

MST/622     

Effects of Sn segregation and precipitates on creep response of Mg‐Sn alloys

Mg‐Sn alloys are promising for the development of new cheap creep resistant magnesium alloys. In the present paper, the creep behaviours of Mg‐Sn and Mg‐Sn‐Ca alloys were examined at the constant temperature and different stresses. The measurements of stress exponents indicate that the dislocation climbing is the dominant mechanism during the creep of Mg‐3Sn or Mg‐3Sn‐2Ca alloys. The poor creep resistance of the binary Mg‐3Sn alloy is caused by the easy movement of dislocation and the segregation of Sn at the boundaries. Both T4 and T6 heat treatments improve the creep resistance of Mg‐3Sn alloy due to the alleviation of Sn segregation at grain boundaries and the precipitation of Mg₂Sn particles, respectively. Ca is an effective alloying element to increase the creep resistance of Mg‐Sn alloys. The Ca addition leads to the formation of thermal stable phases Mg₂Ca and CaMgSn in Mg‐3Sn‐Ca alloys. These two phases effectively hinder the movement of dislocations and the sliding of grain boundaries. On the other hand, the addition of Ca alleviates the segregation of Sn by the interaction of Ca with Mg and Sn to form the phase CaMgSn.