FORMATION LAW OF PHASES IN ULTRAFINE POWDERS OF Al-Cu ALLOY PREPARED BY GAS EVAPORATION PROCESS

１ＩＮＴＲＯＤＵＣＴＩＯＮＵｌｔｒａｆｉｎｅｐｏｗｄｅｒｓｗｉｔｈａｐａｒｔｉｃｌｅｓｉｚｅｌｅｓｔｈａｎ１００ｎｍｈａｖｅｅｘｃｅｌｅｎｔｐｒｏｐｅｒｔｉｅｓｉｎｃｏｎｔｒａｓｔｔｏｃｏａｒｓｅｇｒａｉｎｍａｔｅｒｉａｌｓ［１,２］ａｎｄｈａｖｅｗ...     

Formation regularity of phases in nanometer powders of Al-Fe alloy prepared by gas evaporation

1　ＩＮＴＲＯＤＵＣＴＩＯＮＮａｎｏｍｅｔｅｒａｌｌｏｙｐｏｗｄｅｒｓａｒｅｅｘｐｅｃｔｅｄｔｏｅｘｈｉｂｉｔｕｎｉｑｕｅｃｈａｒａｃｔｅｒｉｓｔｉｃｓｗｈｉｃｈｃａｎｎｏｔｂｅｏｂｔａｉｎｅｄｆｏｒｐｕｒｅｍｅｔａｌｐｏｗｄｅｒｓａｎｄｃｏｎｖｅｎｔｉｏｎａｌｍａｔｅｒｉａｌｓ .Ｍｏｒｅｒｅｃｅｎｔｌｙ ,ａｓｅｒｉｅｓｏｆｓｔｕｄｉｅｓｏｎｔｈｅｐｒｅｐａｒａｔｉｏｎｔｅｃｈ ｎｉｑｕｅａｎｄｐｒｏｐｅｒｔｉｅｓｏｆｎａｎｏｍｅｔｅｒｐｏｗｄｅｒｓｗｅｒｅｃａｒ ｒｉｅｄｏｕｔ,ｓｅｖｅｒａｌｐｒ…     

气相蒸发Ti-Fe系合金纳米粉末相生成规律及尺寸效应研究

采用电弧加热蒸发法制备出粉末粒度在5nm～30nm的Ti-Fe系合金纳米粉末，研究了纳米粉末的相生成规律以及混合物粉末的尺寸效应。实验结果表明，纳米粉末中化合物相的生成规律与Ti-Fe合金平衡相图的不同。蒸发Fe含量大于73％（质量分数，下同）的母合金时易得到FCC相和Fe2Ti相，而蒸发Ti含量大于47％的母合金易得到以FCC相和FeTi相为主的粉末，且所有粉末中FCC相含量最多。当母合金中Fe含量为53％时，粉末中FeTi相的相对含量是所有粉末中最高的。只有在蒸发Ti含量为90％的母合盒所得的粉末中检测到了少量Ti单质相。FCC相的d（111）晶面间距随母合金中Ti含量的增加而增加，说明FCC为固溶体相。DSC结果表明，纳米粉末的平均熔点明显低于粉末中各个合金相在平衡状态下的熔点。     

储氚合金ZrCo0.8M0.2 (M = Co, Cu, Cr, Mn, Al)的性能研究

采用电弧熔炼的方法在氩气气氛中熔炼了ZrCo_0.8M_0.2 (M = Co、Cu、Cr、Mn、Al)合金。合金的主相均为ZrCo相,但Cr、Mn和Al部分替代Co后形成了第二相。Cr替代形成了Zr₂Co和ZrCr₂相,Mn替代形成了Zr₂Co和ZrMn₂相,Al替代形成Zr₃Co和Zr₆CoAl₂相。Cr和Mn的替代使合金的晶胞体积减小,而Cu和Al的替代使晶胞体积增大。Cu、Cr、Mn和Al替代后,ZrCo_0.8M_0.2合金的平台压变化不明显,但吸氢量出现了不同程度的降低。Cr和Mn元素的替代明显改善了ZrCo合金在室温下的活化性能。Cr和Mn元素的替代降低了高温下ZrCo合金发生歧化反应的速率,这主要是由于Cr和Mn元素的掺杂减少了氢原子占据不稳定位置8f₂ 和8e的数量,从而降低了歧化反应发生的驱动力。     

Enthalpy of formation of quasicrystalline phase and ternary solid solutions in the Al-Fe-Cu system

1. Introduction A novel intermetallic-phase quasicrystal was discovered in 1984. At first, the quasicrystalline phase was observed in rapidly quenched alloys of the Al-Mn system [1]. Till date quasicrystalline phases have been obtained in more than 100 systems; mainly Al, Cu, Ti, and Zr-based systems. The pecu- liarity of the quasicrystalline phases is that the exis- tence of symmetry axes for the fifth and tenth orders are forbidden by classic crystallography. The quasi- crystalline phases…     

AZ31B合金固相反应型Al_2O_3基纳米复相陶瓷涂层热震性能研究

在镁合金AZ31B表面采用同相反应法制备了Al2O3基纳米复相陶瓷涂层,采用机械合金化(MA)制备了超细粉体,对粉体的相组成及粒度进行了测试,并用X射线衍射分析了涂层的相组成.结果表明,在MA后粉体的粒度接近纳米级;热固化后涂层中有Al2O3、TiB2、MgAl2O4、Zn6Al2O9和Ti3B4新相产生;涂层具有较好的抗热震性能,400℃耐热冲击达35次以上.     

机械合金化制备的Al-Pb-Cu合金结构与摩擦性能

用机械合金化方法制备了Al-Pb-Cu合金。X射线衍射（XRD）和扫描电镜（SEM）分析表明，随机械合金化的进行，Al-Pb-Cu合金中相继有Cu9Al4和CuAl2相形成，在随后的烧结过程中，CuAl2相农渐增加，而Cu9Al4相逐渐消失，最终获得了在Al基体上弥散分布为Pb相和CuAl2相的组织，与Al-Pb二元合金相比，Cu的加入在一定程度上抑制了Pb相的长大，摩擦磨损性能测定表明，Al-Pb-Cu合金的摩擦磨损性能比相同方法制备的Al-Pb二元合金有了较大提高，当Cu含量（质量分数）为4．5％时，合金的耐磨性最佳。     

Influence of Al Addition on Oxidation Behavior of Cu–Ni–Cr Alloys at 973–1073 K in 1.01 × 10<Superscript>2</Superscript> kPa Pure Oxygen

The oxidation behavior of Cu–20Ni–15Cr–2.5Al and Cu–20Ni–20Cr–2.5Al alloys was studied at 973–1073 K in 1.01 × 10² kPa pure oxygen. The oxidation kinetics exhibited large deviations from the parabolic rate law and were comprised of three or four quasi-parabolic stages. Oxidation rates of the present alloys were much lower than those previously reported for a Cu–20Ni–20Cr alloy. Cu–20Ni–15Cr–2.5Al alloy formed a continuous scale of chromia in contact with the alloy, while at other locations, the scale formed deep protrusions into alloy along β phases. Cu–20Ni–20Cr–2.5Al alloy formed a continuous scale of chromia with a small quantity of light and unoxidized precipitates of α phase, especially at 1073 K. There was a thin layer depleted in Cr beneath the continuous scales of chromia. The addition of 2.5 at.% Al to Cu–Ni–Cr alloy made the diffusion of reactive component Cr become much faster and facilitated the formation of a continuous external scale of chromia for a lower Cr content.     

MICROSTRUCTURE AND DECOMPOSITION OF RS Al-Fe-Cr-Zr ALLOY

ＭＩＣＲＯＳＴＲＵＣＴＵＲＥＡＮＤＤＥＣＯＭＰＯＳＩＴＩＯＮＯＦＲＳＡｌ－Ｆｅ－Ｃｒ－ＺｒＡＬＬＯＹ￥ＸｉａｏＹｕｄｅ；ＬｉＳｈｏｎｇｒｕｉ；ＸｉｅＹｏｎｇａｎ；ＸｕＹｉｈｅｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅａｎｄＥｎｇｉ...     

Thermodynamic modeling of Al–Ce–Mg phase equilibria coupled with key experiments

The ternary Al–Ce–Mg phase diagram was calculated using the Calphad method and investigated with selected key experiments. Arc melted alloys were annealed at 400 °C for 500 h and the phases were analyzed using quantitative X-ray powder diffraction (XRD). Differential thermal analysis (DTA) was also performed on an alloy with a composition near the ternary phase Al₁₃CeMg₆ (τ). Temperatures above 1000 °C could be attained due to a special sealing of the sample under argon by welding in a tantalum crucible to avoid evaporation and oxidation. Only with this procedure could reproducible and reliable DTA signals be obtained. The present experimental investigation and the consistent thermodynamic calculation show that the “ternary phase” Ce(Mg,Al)₂, seemingly isolated in the ternary at 400 °C, can be rationalized as a single solid solution phase between the binary end members if a larger temperature range and a solid state miscibility gap is considered. It is demonstrated that previously reported low values of ternary liquidus temperatures must be related to other phase equilibria. The actually found ternary liquidus temperatures are much higher and widely governed by the high melting compound Ce(Al,Mg)₂ and also by Al₁₁Ce₃ with primary solidification fields stretching far into the ternary system.     

HT250 铸铁表面等离子合金化 AlCoCrCuFex MnNiCx高熵合金复合涂层

目的通过等离子合金化高熵合金涂层,提高铸铁表面耐磨性。方法采用等离子合金化法,以等摩尔比的Al,Co,Cr,Cu,Mn,Ni单质金属粉在HT250铸铁表面制备高熵合金复合涂层。通过SEM,EDS,XRD等分析涂层的组织,测试涂层的显微硬度分布。结果由于铸铁基体少量熔化,基体中的Fe和C元素进入涂层,形成了厚度约为0.2 mm的Al Co Cr Cu FexMn Ni Cx高熵合金涂层。从涂层表面到基材,体系的混合熵呈高熵-中熵-低熵的梯度变化。涂层主要由高熵合金的枝晶和枝晶间渗碳体、σ相等组织构成,主要有FCC,BCC,Fe3C及σ相。涂层的显微硬度大约为350~600HV0.2,明显高于铸铁基体的硬度(200~230HV0.2)。结论通过等离子合金化可以在铸铁表面形成高熵合金+碳化物的复合涂层,提高了铸铁的显微硬度,有利于铸铁表面耐磨性的提高。     

纳米多孔铜制备及其电化学性能研究

通过真空熔炼和快速凝固技术制备了Cu-55Al(at%)合金铸锭和快淬薄带,用稀盐酸浸泡法对所得合金进行了化学脱合金。采用XRD、SEM和TEM等方法对脱合金前后的相组成及微观形貌进行了表征。结果表明,合金原始物相均由AlCu和Al2Cu相组成,快淬薄带中Al2Cu相含量更高。二者经脱合金后均能获得三维无序网状多孔铜,孔带平均尺寸分别为83、58 nm。此外,块体多孔铜中虽有少量Al残余,但孔带光滑完整。而合金薄带虽然能够完全脱Al,但孔带表面粗糙,并含有少量的Cu2O。电化学测试表明,多孔铜在碱性条件下电氧化甲醇的电流密度较光滑铜电极提高了25倍,同时还表现出优良的电容性能。     

Preparation of low-oxygen-containing Ti–48Al–2Cr–2Nb alloy powder by direct reduction of oxides

A high-purity Ti–48Al–2Nb–2Cr alloy powder with an oxygen content as low as 0.0572 wt.% and a particle size of <150 μm was produced from a mixture of TiO₂, Al₂O₃, Nb₂O₅, and Cr₂O₃ powders through reduction with magnesium and deoxidation with calcium. The phase and composition of the products were analyzed. The final product mainly included γ-TiAl and minor α₂-Ti₃Al phases, and Ti, Al, Cr, and Nb were homogenously distributed in the powder with a mole ratio of 49.73:43.51:2.05:1.98. The reduction and deoxidation mechanisms were investigated by thermodynamic modeling using the HSC Chemistry software and Pandat software based on the Ti alloy database.     

纳米钨合金粉末的制备技术

钨合金包括W－Ni-Fe,W-Ni-Cu,W-Cu,WC-Co等钨基合金材料。钨合金材料将是21世纪出现的一种多功能高性能的多胜任的新型材料。有杉纳米粉末制备的亚微或微米钨合金块体材料具有非常优越的潜在物理力学性能,用作高性能结构件和高性能电子、微电子等功能材料方面都将具有很大的潜在优势,可以更好地满足高性能新型材料的要求。本文综合近几年来国内外纳米钨合金的研究状况,详细地介绍了有关纳米钨合金粉末的制备技术,预测了今后钨合金材料的研究方向。     

Effect of brazing conditions on the microstructure and mechanical properties of duplex stainless steels to Cr−Cu alloy with Cu−base insert metal

The brazing of a copper-chromium alloy and DSS (Duplex stainless steel) was conducted under various conditions to investigate the bonding phenomena, microstructures and mechanical properties. The reactions of liquid insert metal with dissimilar base metals, a Cu−Cr alloy and DSS produced various phases in the bond zone. The chemical composition and the volume fraction of the phases varied as a function of the brazing conditions. The Cu phase for the DSS and piece of stainless steel separated from the DSS was produced from the reaction of the insert metal and the SSS. In addition, the Cr−Mn phase, Mn−Fe phase and Fe−Cr phase were formed by the reaction between the insert metal and each base metal. As the brazing temperature and time increased; the amounts of the Cu phase and the number of stainless steel pieces increased. In addition, the Mn−Fe phase varied compared to the Fe−Cr phase after brazing at 1273 K at 0 min. The Cr−Mn phase initially increased but eventually decreased after holding times of 15 min at 1273 K and 7 min at 1303 K.     

Influence of alloy ingredients on mechanical properties of ternary boride hard alloy clad materials

Using Mo, B-Fe alloy and Fe powders as raw materials, and adding C, Cr and Ni ingredients, respectively, or C, Cr and Ni mixed powders, ternary boride hard alloy clad materials was prepared on Q235 steel substrate by means of in-situ reaction and vacuum liquid phase sintering technology. The influence of alloy ingredients on the mechanical properties of ternary boride hard alloy clad materials was investigated. The results indicate that a mixture of 0.8% C, 5% Cr and 2% Ni ingredients gives a ternary boride hard alloy clad material with optimal mechanical properties, such as high transverse rupture strength, high hardness and good wear resistance.     

不同SPS烧结温度Ti-45Al-5.5(Cr,Nb,B,Ta)合金的显微组织及力学性能(英文)

采用高能球磨和放电等离子烧结(SPS)技术,制备成分为Ti-45Al-5.5(Cr,Nb,B,Ta)的TiAl合金块体,随后对TiAl合金进行热处理。研究在不同SPS烧结温度下制备的TiAl合金经过热处理后的显微组织和力学性能。结果表明:高能球磨后的合金粉末形状不规则,粉末颗粒尺寸大约为几十微米。XRD分析表明,机械球磨后的粉末由TiAl和Ti3Al两相组成;烧结后的Ti-45Al-5.5(Cr,Nb,B,Ta)合金块体主要是TiAl相,以及少量的Ti3Al和TiB2相。当烧结温度为900°C和1000°C时,合金的显微组织为双相结构,并伴随有一些细小的等轴γ晶粒和细小的针状TiB2相。当烧结温度从900°C上升到1000°C时,Ti-45Al-5.5(Cr,Nb,B,Ta)合金的显微硬度变化不大,抗压强度从1812MPa提高到2275MPa,压缩率从22.66%增加到25.59%,合金的断裂方式为穿晶断裂。     

Overheating temperature of 7B04 high strength aluminum alloy

The microstructure and overheating characteristics of the direct chill semicontinuous casting ingot of 7B04 high strength aluminum alloy, and those after industrial homogenization treatment and multi-stage homogenization treatments, were studied by differential scanning calorimetry(DSC), optical microscopy(OM) and scanning electron microscopy with energy dispersive X-ray spectroscopy(SEM-EDX). The results show that the microstructure of direct chill semicontinuous casting ingot of the 7B04 alloy contains a large number of constituents in the form of dendritic networks that consist of nonequilibrium eutectic and Fe-containing phases. The nonequilibrium eutectic contains Al, Zn, Mg and Cu, and the Fe-containing phases include two kinds of phases, one containing Al, Fe, Mn and Cu, and the other having Al, Fe, Mn, Cr, Si and Cu. The melting point of the nonequilibrium eutectic is 478 ℃ for the casting ingot of the 7B04 alloy which is usually considered as its overheating temperature. During industrial homogenization treatment processing at 470 ℃, the nonequilibrium eutectic dissolves into the matrix of this alloy partly, and the remainder transforms into Al2CuMg phase that cannot be dissolved into the matrix at that temperature completely. The melting point of the Al2CuMg phase which can dissolve into the matrix completely by slow heating is about 490 ℃. The overheating temperature of this high strength aluminum alloy can rise to 500-520 ℃. By means of special multi-stage homogenization, the temperature of the homogenization treatment of the ingot of the 7B04 high strength aluminum alloy can reach 500 ℃ without overheating.     

Mn-30Al中间合金对镁合金的晶粒细化

采用真空淬火炉制备出含ε-AlMn相的Mn-30Al中间合金和含γ_2-Al_8Mn_5相的Mn-30Al中间合金,观察了两种中间合金的组织,并探讨ε-AlMn相、γ_2-Al_8Mn_5相、Mn和Al对镁合金的晶粒细化效果.试验表明,相比添加Mn、Al,含γ_2-Al_8Mn_5相的Mn-30Al中间合金对AZ31镁合金存在一定的细化效果,含ε-AlMn相的Mn-30Al中间合金对AZ31镁合金具有更好的细化效果.当含ε-AlMn相的Mn-30Al中间合金添加量为0.4%时,AZ31镁合金的晶粒尺寸由原来的898μm减小至320 μm,Mg-Zn合金晶粒尺寸由原来的320 μm减小至180μm.通过面错配度计算,ε-AlMn可以成为初生α-Mg晶粒的良好异质形核核心.     

Mn元素在7A99铝合金中微观组态分布的研究

通过半连续铸造方式向7A99铝合金中添加0.4％Mn(质量分数)元素,采用SEM、TEM、HRTEM与三维原子探针(3DAP)开展Mn元素在7A99铝合金铸锭、均匀化以及固溶时效过程中的微观组态分布的研究.结果表明,Mn元素在7A99铝合金铸锭中主要以晶界处鱼骨状的含AlZnMgCuMn的MgZn2型非平衡共晶化合物形...