Amorphous forming ranges of Al-Fe-Nd-Zr system predicted by Miedema and geometrical models

A method based on the semi-empirical Miedema model and a geometrical model was used to study the glass forming abilities(GFA) and the amorphous forming ranges of Al-Fe-Nd-Zr system and its constituent ternary systems.The amorphous forming composition ranges were analyzed based on different criteria such as ΔGam-ss and PHSS(PHSS=ΔHchem(ΔSC/R)(ΔSσ/R)) for Al-Fe-Nd system.The predicted amorphous forming range was in good agreement with the experimental results.The results showed that the criterion of ΔGam-ss was more accurate,and agreed well with the experiment results.The Gibbs free energy difference ΔGam-ss and parameter PHSS were then used to predict the amorphous forming composition range for the rest of the constitutive ternary systems of Al-Fe-Nd-Zr.In addition,the amorphous forming composition ranges of the(Al-Fe-Zr)100–x Ndx(x=50,60,70) systems were predicted by ΔGam-ss and the modified parameter PHSS.The Gibbs free energy of Al10(Fe1–x Zrx)30Nd60 were also calculated.The GFA parameter PHSS indicated that the composition with the highest GFA was Al33.5Fe13.5Zr3Nd50 for the(Al-Fe-Zr)50Nd50 system,Al28.8Fe10Zr1.2Nd60for the(Al-Fe-Zr)40Nd60 system and Al22.8Fe6.9Zr0.3Nd70 for the(Al-Fe-Zr)30Nd70 system,and the results suggested that those alloys with high content of Al had higher GFA.The appropriate content of neodymium and zirconium resulted in the lower value of PHSS and increased the GFA obviously.     

Experimental investigation on phase equilibria of Ce-Sn-Zn system at 400℃

The Ce-Sn-Zn alloys were prepared by furnace melting. The isothermal section of the Ce-Sn-Zn system at 400 oC over the whole composition range was established by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). A new ternary compound, CeSn 2 Zn 2 , was discovered in the present work. This compound adopted CaBe 2 Ge 2 structure type (space group P4/nmm) with the lattice parameters of a=0.4455 (9) nm and c=1.0348 (1) nm. The existence of previously known ternary compounds, CeSnZn and Ce 2 SnZn 3 , were confirmed, too. The maximum solubility of Zn in CeSn 3 was determined to be 12.7 at.%.     

A Comparative Study on Hydrogen Diffusion in Amorphous and Crystalline Metals Using a Molecular Dynamics Simulation

A comparative study on hydrogen diffusion in amorphous and simple crystalline structures has been carried out using molecular dynamics simulations. The Cu-Zr bulk metallic glass (BMG) system is selected as the model material and a modified embedded-atom method (MEAM) interatomic potential for the Cu-Zr-H ternary system is developed for the atomistic simulation. It is found that the diffusivity of hydrogen in amorphous alloys is lower than that in open structured crystals but higher than that in close-packed crystals. The hydrogen diffusion in amorphous alloys is strongly hydrogen concentration dependent compared to crystals, increasing as the hydrogen content increases, and the Arrhenius plot of hydrogen diffusion in amorphous alloys shows an upward curvature. The reasons to rationalize all the findings are discussed based on the variety of energy state and migration energy barrier for interstitial sites in amorphous alloys.     

Development of bulk metallic glasses based on the Dy-Al binary eutectic composition

A series of dysprosium-based ternary, quadruple, and quintuple bulk metallic glasses （BMGs） based on Dy-Al binary eutectic composition were obtained with the partial substitution of Co, Gd, and Ni elements, for dysprosium. The results showed that the Dy31Gd25Co20Al24 alloy, which had the best glass forming ability （GFA）, could be cast into an amorphous rod with a diameter of 5 ram. The GFA of alloys was evaluated on the basis of the supercooled liquid region width, 7 parameter, the formation enthalpy, and the equivalent electronegativity difference of amorphous alloys. It was found that the eutectic composition was closely correlated with the GFA of the Dy-based BMGs.     

Electromotive Force Measurements in the Ternary System Bi-In-Zn

The thermodynamic properties of the ternary Bi-In-Zn system were determined with the electromotive force (EMF) method using a liquid electrolyte. Four different cross sections with constant In/Bi ratios of 1:2, 1:1, 2:1, and 9:1 were applied to measure the thermodynamic properties of the ternary system in the temperature range between the liquidus temperature of the alloys and 973 K (700 °C). Zinc was added in steps of 5 at. pct from 5 to 90 pct. The partial free energies of Zn in liquid Bi-In-Zn alloys were determined as a function of concentration and temperature. The integral Gibbs free energy and the integral enthalpy of the ternary system at 873 K (600 °C) were calculated by Gibbs–Duhem integration. The ternary interaction parameters were evaluated using the Redlich–Kister–Muggianu polynomials.     

Thermodynamic assessment of the Cu-Ti-Zr system. I. Cu-Ti system

The CALPHAD method is used for the thermodynamic assessment of the Cu-Ti system that bounds the ternary Cu-Ti-Zr system, which is capable of forming amorphous alloys. The self-consistent parameters of thermodynamic models of the phases are obtained from data on the phase equilibria and thermodynamic properties of liquid alloys and intermetallic compounds. The Gibbs energy of the liquid phase is described using the associated ideal solution model. To describe the thermodynamic properties of the Cu₄Ti and CuTi intermetallic compounds with homogeneity range, sublattice models are used. The calculated phase diagram of the system and the thermodynamic properties of the phases are in good agreement with experimental data.     

Solidification structures in rapidly quenched Cu-Ti-Zr alloys

The melt-spinning and pulsed laser-quenching techniques were used to generate fast cooling rates necessary to form metallic glass in ternary Cu-Ti-Zr alloys. Even though the cooling rates generated during melt-spinning were much lower than those generated during pulse laser-quenching, the amount of glass obtained in the melt spun alloys was much larger than in the laser-quenched alloys. The microstructure of the laser-quenched alloys consisted of metallic glass and a fine microcrystalline fcc phase, whereas the melt-spun ribbons of the same compositions were completely amorphous. Glass transition temperature trends in the ternary system were determined from alloys of composition traversing linearly from the binary Cu-Ti side to the Cu-Zr side. These trends showed a nearly linear change of T_g with composition.     

A study on the microstructural evolution of Al-25 at. pct V-12.5 at. pct M (M = Cu,Ni, Mn) powders by planetary ball milling

The alloying behavior of Al-25 at. pct V-12.5 at. pct M (M = Cu, Ni, Mn) by planetary ball milling of elemental powders hours as been investigated in this study. In Al₃V binary system, an amorphous phase was produced after 6 hours and the amorphous phase was mechanically crystallized after 20 hours. The large difference in the diffusivities between Al and V atoms in Al matrix results in the formation of the amorphous phase when the homogeneous distribution of all the elements in a powder was achieved at 6 hours. According to thermal analyses, the amorphous phase in the binary Al₃V was crystallized at 350 °C. The addition of ternary elements (Cu, Ni, Mn) increased the activation energy for the crystallization to D0₂₂ phase by interfering with the diffusion process. Therefore, ternary element addition improved the thermal stability of the amorphous structures. The amorphous phase in the 12.5 at. pct Ni added Al₃V was crystallized to D0₂₂ phase at 540 °C. The mechanical crystallization of the amorphous phase in the ternary element-added Al-V system either occurred later or was not observed during ball milling up to 100 hours. It is thought that the amorphous intermetallic compacts could be produced more easily in ternary element-added alloys by using an advanced consolidation method.     

新型(Fe,Co)-Zr-RE-B非晶合金的热稳定性和磁性

利用旋铸技术制备了一种新型的含稀土元素的铁基非晶合金。研究了Nd含量对Fe70Co8Zr7-xNdxB15(x=0～6%原子数分数)合金的非晶形成能力、热稳定性和磁性能的影响。当该合金系的Nd含量在0～6%(原子数分数)变化时,其饱和磁感应强度(Js)在1.10T～1.37T范围内变化,矫顽力(Hc)在2.28A/m～8.15A/m范围内变化。Js随Nd含量的增加而增加,当Nd含量为2%和3%时,其Hc值均在3A/m以下,且在Nd含量为2%时,具有最高的非晶形成能力(glassformationability简称GFA)即大的ΔTx(达61K);同时又有良好的软磁性能,其Js和Hc值分别为1.25T和2.28A/m。经对比得出,Fe70Co8Zr5RE2B15(RE=Ce、Pr、Gd和Tb)合金与Fe70Co8Zr5Nd2B15具有相近的非晶形成能力和磁性能。     

球磨法制备Mg-Cu非晶态合金粉末

本文研究了Mg—Cu二元相图的三个共晶点成分配方和两个化合物成分配方在球磨条件下非晶态合金的形成能力。XRD结果显示：除一个共晶点成分配方外，其它所有成分配方都能形成非晶态合金；非晶形成能力由大到小依次为MgCu2(化合物)，Mg58Cu42(共晶点)，Mg2Cu(化合物)，Mg85Cu15(共晶点)，Mg22Cu78(共晶点)。显然，作为选择非晶态合金成分的判据来说，Schwarz与Johnson的两个条件准则比Davies的共晶线准则更加合适。非晶形成的过程是：首先发生Mg在Cu中的固溶，随后形成过饱和固溶体，最后过饱和固溶体失稳形成非晶态合金。     

Application of free energy-composition diagrams in predicting the sequences of phase transformations in Zr-Nb alloys

The free energy composition diagrams for the Zr-Nb alloy system have been computed from the phase diagram employing Rudman’s technique of phase diagram analysis. The influence of the clustering tendency in the β phase on the sequence of phase transformations in both Zr-rich and Nb (Cb)-rich alloys has been examined. It has been possible to predict different sequences of phase reactions in different ranges of composition and temperature. The experimentally observed phase reactions as reported earlier have been rationalized by the calculated free energy composition plots.     

Experimental study and modeling of the thermodynamic properties of Cu-Fe-Ni melts

The partial mixing enthalpy of nickel in ternary liquid Cu-Fe-Ni alloys is studied at 1873 K along sections characterized by ratios x _Cu: x _Fe = 3, 1, and 1/3 at x _Ni = 0–0.55. The investigations are undertaken using a high-temperature isoperibolic calorimeter. The temperature and composition dependence of the excess mixing Gibbs energy of liquid Cu-Fe-Ni alloys are described in terms of the Muggianu-Redlich-Kister model using the data obtained, the literature data on the activities of liquid alloy components, and the thermodynamic properties of melts of the boundary binary systems. This model is used to calculate isotherms of the thermodynamic properties of the liquid alloys over the entire composition range. The contribution of a ternary interaction to the integral mixing enthalpy of liquid Cu-Fe-Ni alloys is found to be mainly positive.     

Crystallization of amorphous Fe- P- C alloys

The transformation of amorphous Fe-P-C alloys from the amorphous state to crystalline state was studied by differential scanning calorimetry (DSC), X-ray diffractometry (XRD) and transmission electron microscopy (TEM). Compositions included iron and phosphorus rich alloys and alloys with compositions near the eutectic composition. The crystallization of Fe-P-C alloys proceeded by the following processes: for the iron rich alloy, bcc α Fe precipitated first; for the phosphorus rich alloy, Fe₂P and iron carbide precipitated first; for the alloys near the eutectic line, the eutectic reactions dominated, although some α Fe or Fe₂P plus iron carbide crystals were observed. The composition dependence of the transformation can be explained successfully by a free energy model with the help of the phase diagram. From DSC and TEM results, the nucleation rate of the α Fe precipitate decreased with time in the Fe rich alloys according to the recrystallization theory of Avrami. Formerly Research Fellow in the Department of Metallurgy and Materials Science, University of Pennsylvania This paper is based on a presentation made at a symposium on “Recovery Recrystallization and Grain Growth in Materials” held at the Chicago meeting of The Metallurgical Society of AIME, October 1977, under the sponsorship of the Physical Metallurgy Committee.     

The effect of composition and milling conditions on the structure of mechanically alloyed Mg-Al based alloys

Mg-Al based alloys were mechanically alloyed under varying conditions. Elemental reaction times correlated with known diffusion coefficients and elemental hardness, but milling temperature had almost no effect over a 200 °C range. Increasing impact energy caused the steady-state level of crystallinity to increase. Alloys with up to 6 at. pct of Ti, Y, Ca, Zr, V, Er, or Pr yielded amorphous alloys near the composition Mg₄₀Al₆₀. Certain phases were suppressed by mechanical alloying, while others became more dominant than in the equilibrium phase diagram. These effects are explained by differential scanning calorimetry (DSC) results, which indicate they are growth rate controlled during mechanical alloying. Hard elements such as Cr and Mo with positive free energy of mixing did not react completely even after relatively long milling times.     

Phase structure and electrochemical properties of laser sintered La2MgNi9 hydrogen storage electrode alloys

Phase structure and electrochemical properties of laser sintered La2MgNi9 alloys were studied. The sintered alloys contained a main phase, LaNi5, and a ternary La-Mg-Ni phase, with a PuNi3 structure and a small amount of LaMgNi4. The ternary La-Mg-Ni phase with a PuNi3 structure had the composition of La1.8Mg1.2Ni9 and La2MgNi9, for alloys laser sintered at 1000 and 1400 W, respectively. Owing to further reactions between LaNi5 and LaMgNi4, the amount of the PuNi3 phase increased for alloys sintered at 1400 W. Both alloys had good activation property (three charge/discharge cycles). The discharge capacities of the sintered alloys were 321.8 and 344.8 mAh/g, respectively. Compared with the alloy laser sintered at 1000 W, the poor cyclic stability of the alloy sintered at 1400 W was mainly attributed to the lower corrosion resistance of the La2MgNi9 phase.     

Study on Annealing Embritlement of Fe-B-Si Amorphous Alloy

ＳｔｕｄｙｏｎＡｎｎｅａｌｉｎｇＥｍｂｒｉｔｌｅｍｅｎｔｏｆＦｅ┐Ｂ┐ＳｉＡｍｏｒｐｈｏｕｓＡｌｏｙＣａｏＸｉｎｇｇｕｏ①，ＧｕｏＺｅｃｈｅｎ①，ＣｈｅＸｉａｏｚｈｏｕ②，ＬｉｕＰｉｎｇ①，ＹｉｎＢｉａｏ①ＡＢＳＴＲＡＣＴＴｈｅｌａｗａｎｄａｃｔｉｖ...     

Thermodynamic and Kinetic Study of Crystallization Reaction of Fe/Dy Multilayers Form Amorphous State

ＭａｇｎｅｔｉｃｆｉｌｍｓｏｆＴＭ/ＲＥｃａｎｔｒａｎｓｆｏｒｍｔｏａｍｏｒｐｈｏｕｓｓｔａｔｅｂｙｍｅａｎｓｏｆａｄｊｕｓｔｉｎｇｔｈｅｉｒｍｏｄｕｌａｔｉｏｎｐｅｒｉｏｄｉｃｉｔｙｄｕｒｉｎｇｄｅｐｏｓｉｔｉｏｎ .Ｔｈｅｆｉｌｍｓｉｎａｍｏｒｐｈｏｕｓｓｔａｔｅｅｘｈｉｂｉｔｐｅｒｐｅｎｄｉｃｕｌａｒａｎｉｓｏｔｒｏｐｙａｎｄａｒｅｐｒｏｍｉｓｉｎｇｃａｎｄｉｄａｔｅｓｆｏｒｍａｇｎｅｔｉｃｒｅｃｏｒｄｉｎｇｍｅｄｉａ .Ａｍｏｒｐｈｏｕｓｓｔａｔｅｉｓｔｈｅｒｍｏｄｙｎａｍｉｃａｌｌｙｍｅｔ…     

成分对非晶态Fe—B—Si合金退火脆化行为的影响

本文研究了Ｂ和Ｓｉ的含量及Ｆｅ／（Ｂ＋Ｓｉ）相对含量对非晶态Ｆｅ－Ｂ－Ｓｉ合金退火脆化行为的影响；分析了在常规热处理条件下，利用成分的变化，获得延性与磁性综合性能的可能性。实验结果表明，非晶态Ｆｅ－Ｂ－Ｓｉ合金的退火脆化行为具有较大的成分依赖性，位于Ｆｅ７９ａｔ％－８１ａｔ％，Ｂ１１ａｔ％，Ｓｉ８ａｔ％－９ａｔ％成分范围内的Ｆｅ－Ｂ－Ｓｉ非晶态合金的退火脆化敏感性最小，脆化仍发生于晶化开始之前...     

Study on Electrodeposition of Ho-Co Alloy in Dimethylsulfoxide

Ｎｏｗｒａｒｅｅａｒｔｈｓ ｉｒｏｎａｌｌｏｙｓａｒｅｐｒｏｄｕｃｅｄｍａｉｎｌｙｂｙｖａｃｕｕｍｅｖａｐｏｒａｔｉｏｎ ,ｃａｔｈｏｄｅｓｐｕｔ ｔｅｒｉｎｇｏｒｉｏｎｐｌａｔｉｎｇ ,ｗｈｅｒｅｔｈｅｃｏｓｔｉｓｈｉｇｈａｎｄｔｈｅｔｅｃｈｎｏｌｏｇｙｉｓｃｏｍｐｌｉｃａｔｅｄ .Ｅｌｅｃｔｒｏｄｅ ｐｏｓｉｔｉｏｎｍａｙｂｅａｃｏｍｐａｒａｔｉｖｅｌｙｇｏｏｄｗａｙｆｏｒｉｔｓｌｏｗｃｏｓｔａｎｄｓｉｍｐｌｅｔｅｃｈｎｏｌｏｇｙ .Ｈｏｗｅｖｅｒｉｔｉｓｄｉｆｆｉｃｕｌｔｔｏｅｌｅｃｔｒｏｄｅｐｏｓ…