Role of compositional changes on thermal,magnetic,and mechanical properties of Fe-P-C-based amorphous alloys

This work aimed to tune the comprehensive properties of Fe-P-C-based amorphous system through investigating the role of microalloying process on the crystallization behavior,glass forming ability(GFA),soft magnetic features,and mechanical properties.Considering minor addition of elements into the system,it was found that the simultaneous microalloying of Ni and Co leads to the highest GFA,which was due to the optimization of compositional heterogeneity and creation of near-eutectic composition.Moreover,the FeCoNiCuPC amorphous alloy exhibited the best anelastic/viscoplastic behavior under the nanoindentation test,which was owing to the intensified structural fluctuations in the system.However,the improved plasticity by the extra Cu addition comes at the expense of magnetic properties,so that the saturation magnetization of this alloying system is significantly decreased compared to the FeCoPC amorphous alloy with the highest soft magnetic properties.In total,the results indicated that a combination of added elemental constitutes,i.e.,Fe69Co5Ni5Cu1P13C7 composition,provides an optimized state for the comprehensive properties in the alloying system.     

Thermal and optical studies of an amorphous InSe9 alloy produced by mechanical alloying

In this paper we investigated thermal and optical properties of an amorphous alloy of the In–Se system. The amorphous InSe₉ alloy was produced by mechanical alloying and it was studied using Differential Scanning Calorimetry and microPhotoluminescence spectroscopy techniques, and from them several properties, such as glass transition and crystallization temperatures and energies and the optical gap energy were determined and compared to the values found in other alloys of the In–Se system. This comparison revealed some differences among our alloy produced by mechanical alloying and alloys produced by other techniques, which is a clear indication of the influence of the fabrication technique in their physical properties. The main differences occur in the activation energies associated with the glass transition and crystallization processes and also in the optical gap energy.     

NANOSTRUCTURED Zr-BASED ALLOYS-PHASE FORMATION AND MECHANICAL PROPERTIES

Newly developed nanostructured Zr/Ti-Al-TM multiphase alloys can provide a large bandwidth of interesting properties, such as mechanical properties. Bulk materials with nanocrystalline/ amorphous and (nano)quasicrystalline/ amorphous microstructure with different volume fractions of nanophases and with different grain sizes can be obtained by slowly cooling the melt as well as by solid state reactions. Multiphase structures are realized either by partial de-vitrification of bulk glass-forming alloys or by defined addition of inert compounds upon alloying. Special preparation techniques e.g. copper mould casting and subsequent controlled annealing and mechanical alloying combined with hot consolidation of powders are described. The phase formation and transformation processes and the thermal stability of such materials in dependence on alloy composition and processing parameters are discussed in detail. Currently, the exploration of properties with respect to potential applications of these nanostructured alloys is still at the beginning. First investigations on the contributions of different phases/ volume fractions to the overall mechanical behaviour will be shown. At room temperature, the deformation behaviour of amorphous/crystalline bulk samples is governed by contributions of all existing phases yielding a high strength of the material.     

Zr基大块非晶中添加元素对非晶形成能力及耐蚀性的影响

运用实空间递归方法研究了添加元素Nb,Ta,Y,La对Zr基非晶合金的非晶形成能力和耐腐蚀性能的影响.用计算机编程构造了Zr基非晶中初始晶化相Zr₂Ni的原子结构模型,用Zr₂Ni中的二十面体原子团簇模拟非晶中的二十面体团簇.计算了替代二十面体中心或顶角位置原子前后Ni,Zr及合金元素的局域态密度、团簇中心Ni与近邻Zr原子及Ni与替代元素Nb,Ta,Y,La间的键级积分,还计算了合金元素替代前后团簇的费米能级.局域态密度计算结果表明：合金元素Cu占据二十面体团 关键词： 电子结构 Zr基大块非晶 非晶形成能力 耐蚀性     

FeSiBP bulk metallic glasses with high magnetization and excellent magnetic softness

Fe-based amorphous alloy ribbons are one of the major soft magnetic materials, because of their superior magnetic properties such as the relatively high saturation magnetization (J_s) of 1.5–1.6 T and good magnetic softness. However, the preparation of the ordinary amorphous magnetic alloys requires cooling rates higher than 10⁴ K/s due to the low glass-forming ability (GFA) and thus restricts the material outer shape. Recently, Fe-metalloid-based bulk metallic glasses (BMGs) containing glass-forming elements such as Al, Ga, Nb, Mo, Y and so forth have been developed. These alloys have high GFA, leading to the formation of BMG rod with diameters of mm-order. However, the glass-forming metal elements in BMGs result in a remarkable decrease in magnetization. Basically, J_s depends on Fe content; hence, high J_s requires high Fe content in the Fe-based amorphous alloys or BMGs. On the other hand, high GFA requires a large amount of glass-forming elements in the alloys, which results in lower Fe content. Therefore, in substances, the coexistence of high J_s and high GFA is difficult. Since this matter should be immensely important from academia to industry in the material field, a great deal of effort has been devoted; however, it has remained unsolved for many years. In this paper, we present a novel Fe-rich FeSiBP BMG with high J_s of 1.51 T comparable to the ordinary Fe–Si–B amorphous alloy now in practical use as well as with high GFA leading to a rod-shaped specimen of 2.5 mm in diameter, obtained by Cu-mold casting in air.     

Unusual glass-forming ability of bulk amorphous alloys based on ordinary metal copper

We report the unusual glass-forming ability (GFA) of a family of Cu-based alloys, Cu46Zr47-xAl7Yx (0相似文献   

The influence of 3d-metal alloy additions on the elastic and thermodynamic properties of CuPd3

Embedded-atom method （EAM） potentials are used to investigate the effects of alloying （e.g. 3d-metals） on the trends of elastic and thermodynamic properties for CuPd3 alloy. Our calculated lattice parameter, cohesive energy, and elastic constants of CuPd3 are consistent with the available experimental and theoretical data. The results of elastic constants indicate that all these alloys are mechanically stable. Further mechanical behavior analysis shows that the additions of Cr, Fe, Co, and Ni could improve the hardness of CuPd3 while V could well increase its ductility. Moreover, in order to evaluate the thermodynamic contribution of 3d-metals, the Debye temperature, phonon density of states, and vibrational entropy for CuMPd6 alloy are also investigated.     

Ductile Bulk Aluminum-Based Alloy with Good Glass-Forming Ability and High Strength

Based on a new approach for designing glassy alloy compositions, bulk Al-based alloys with good glass-forming ability （GFA） are synthesized. The cast Al86Si0.5Ni4.06Co2.94 Y6Sc0.5 rod with a diameter of i mm shows almost fully amorphous structure besides about 5% fcc-Al nucleated in the center of the rod. The bulk alloy with high Al concentration exhibits an ultrahigh yield strength of 1.18 GPa and maximum strength of 1.27 GPa as well as an obvious plastic strain of about 2.4% during compressive deformation. This light Al-based alloy with good GFA and mechanical properties is promising as a new high specific strength material with good deformability.     

Elastic moduli of nanocrystalline binary Al alloys with Fe,Co, Ti,Mg and Pb alloying elements

The paper studies the elastic moduli of nanocrystalline (NC) Al and NC binary Al–X alloys (X is Fe, Co, Ti, Mg or Pb) by using molecular dynamics simulations. X atoms in the alloys are either segregated to grain boundaries (GBs) or distributed randomly as in disordered solid solution. At 0 K, the rigidity of the alloys increases with decrease in atomic radii of the alloying elements. An addition of Fe, Co or Ti to the NC Al leads to increase in the Young’s E and shear μ moduli, while an alloying with Pb decreases them. The elastic moduli of the alloys depend on a distribution of the alloying elements. The alloys with the random distribution of Fe or Ti demonstrate larger E and μ than those for the corresponding alloys with GB segregations, while the rigidity of the Al–Co alloy is higher for the case of the GB segregations. The moduli E and μ for polycrystalline aggregates of Al and Al–X alloys with randomly distributed X atoms are estimated based on the elastic constants of corresponding single-crystals according to the Voigt-Reuss-Hill approximation, which neglects the contribution of GBs to the rigidity. The results show that GBs in NC materials noticeably reduce their rigidity. Furthermore, the temperature dependence of μ for the NC Al–X alloys is analyzed. Only the Al–Co alloy with GB segregations shows the decrease in μ to the lowest extent in the temperature range of 0–600 K in comparison with the NC pure Al.     

Structure and mechanical property variations in Mg–Gd–Y–Zn–Zr alloy depending on its composition and processing conditions

An effect of alloying element content on mechanical properties and precipitate formation in Mg–RE alloys was studied for Mg–8Gd–4Y–1Zn–0.4Zr (wt%) and Mg–10Gd–5Y–1.8Zn–0.4Zr (wt%). It is shown that small variations in the alloying element concentration can be used to manipulate the alloy microstructure and precipitate formation towards eliminating the asymmetry (tension/compression) and anisotropy of yield stress.     

Influence of alloying elements on structure and some physical properties of quenched Sn–Sb alloy

We study the influence of ternary and quaternary alloying elements (Pb, Cd, Cu or Cu–Pb and Cu–Cd) on structural, electrical, hardness and other mechanical properties of Sn–Sb alloys (using an X-ray diffractometer and optical microscope, the double bridge method, Vickers hardness tester and the dynamic resonance method) to produce the best alloy for bearing applications. Adding Cu or Pb to Sn–Sb alloys improves their bearing properties, such as the mechanical properties (elastic modulus, internal friction, hardness and fracture strain) and thermal conductivity. Also, adding Cu, Pb or Cu–Pb to Sn–Sb alloys makes them excellent in their bearing applications and environmental hazards when compared with the Pb ₈₈Sn ₁₀Cu ₂ alloy for automotive applications (FIAT Normalizzazione) and the lead-based Babbitt bearing alloy.     

Microstructure and mechanical properties of nano-Y2O3 dispersed ferritic steel synthesized by mechanical alloying and consolidated by pulse plasma sintering

Ferritic steel with compositions 83.0Fe–13.5Cr–2.0Al–0.5Ti (alloy A), 79.0Fe–17.5Cr–2.0Al–0.5Ti (alloy B), 75.0Fe–21.5Cr–2.0Al–0.5Ti (alloy C) and 71.0Fe–25.5Cr–2.0Al–0.5Ti (alloy D) (all in wt%) each with a 1.0?wt% nano-Y₂O₃ dispersion were synthesized by mechanical alloying and consolidated by pulse plasma sintering at 600, 800 and 1000°C using a 75-MPa uniaxial pressure applied for 5?min and a 70-kA pulse current at 3?Hz pulse frequency. X-ray diffraction, scanning and transmission electron microscopy and energy disperse spectroscopy techniques have been used to characterize the microstructural and phase evolution of all the alloys at different stages of mechano-chemical synthesis and consolidation. Mechanical properties in terms of hardness, compressive strength, yield strength and Young's modulus were determined using a micro/nano-indenter and universal testing machine. All ferritic alloys recorded very high levels of compressive strength (850–2850?MPa), yield strength (500–1556?MPa), Young's modulus (175–250?GPa) and nanoindentation hardness (9.5–15.5?GPa), with up to 1–1.5 times greater strength than other oxide dispersion-strengthened ferritic steels (<1200?MPa). These extraordinary levels of mechanical properties can be attributed to the typical microstructure of uniform dispersion of 10–20-nm Y₂Ti₂O₇ or Y₂O₃ particles in a high-alloy ferritic matrix.     

The nature of distribution of atoms,and its connection with electron structure in a number of ternary alloys on Ni3Mn basis

The influence of alloying the Ni₃Mn alloy with titanium, vanadium, or copper, on the superstructure of the alloy, was studied by the neutron diffraction method. It was shown that Ti, V, and Al stabilize the superstructure of Ni₃Mn, and Cu actively destroys it. The distribution of atoms of the alloying elements along the sites of fcc lattice and its connection with the electron structure of the alloy was analyzed. The different influence of alloying with a third element on the superstructure in alloys Ni₃Mn and Ni₃Fe is explained.     

Minor alloying behavior in bulk metallic glasses and high-entropy alloys

The effect of minor alloying on several bulk metallic glasses and high-entropy alloys was studied. It was found that minor Nb addition can optimize the interface structure between the W fiber and the Zr-based bulk metallic glass in the composites, and improve the mechanical properties. Minor Y addition can destabilize the crystalline phases by inducing lattice distortion as a result to improve the glass-forming ability, and the lattice distortion energy is closely related to the efficiency of space filling of the competing crystalline phases. A long-period ordered structure can precipitate in the Mg-based bulk metallic glass by yttrium alloying. For the high-entropy alloys, solid solution can be formed by alloying, and its mechanical properties can be comparable to most of the bulk metallic glasses.     

Thermal conductivity of an alloy in relation to the observed cooling rate and glass-forming ability

The glass-forming ability (GFA) of an alloy in this case is the largest diameter of a rod which can be cast fully glassy. The present work shows that the thermal conductivity of a liquid alloy has a strong effect on GFA by influencing the cooling rate upon mould casting. The initial cooling rates (for the first 70–100?K of temperature decrease), obtained for Cu-, Zr- and Au-based bulk glass-forming alloys in the liquid state, are found to scale linearly with the thermal conductivities of the liquid base elements. However the low cooling rate found for Ni-based alloy suggests that the heat transfer at the melt–mould interface may also influence the cooling rate. The low thermal conductivity of Ni-based alloys and the correspondingly low cooling rate obtained compared to Cu-based counterparts explains their lower GFA. In the literature, many factors influencing the GFA of alloys have been discussed. To these factors, the present study adds the thermal conductivity of the molten alloy and the melt–mould heat-transfer coefficient. Moreover, the cooling rate depends on temperature and, thus, the critical cooling rate itself is not a suitable parameter for indicating GFA. The cooling can be better described by an appropriate fitting of the cooling curve to an exponential temperature decay function.     

Effects of minor Cu addition on glass-forming ability and magnetic properties of FePCBCu alloys with high saturation magnetization

The effects of minor addition of Cu on glass-forming ability (GFA), thermal stability and magnetic properties of (Fe_0.8P_0.09C_0.09B_0.02)_{100? x} Cu _x (x?=?0–1) alloys were investigated. The introduction of Cu slightly increases the GFA and efficiently improves the primary crystallization of α-Fe nanoparticles. The alloy with 0.3% Cu addition shows the best GFA and the fully glassy rods can be produced up to 2?mm in diameter. The saturation magnetization of the glassy sample with 0.7% Cu addition can be enhanced from 1.44 to 1.60?T after proper heat treatment due to the precipitation of α-Fe nanoparticles in the glassy matrix. The combination of large GFA and high saturation magnetization as well as low cost makes the FePCBCu alloys as a kind of promising soft magnetic materials for industrial applications.     

The effect of Fe doping on structural and magnetic properties of nanocrystallite Co2Cr1-xFexAl Heusler alloys prepared by mechanical alloying

Mechanical alloying has been used to produce nanocrystallite Co2Cr1-xFexAl(x=0,0.4,0.6,1) Heusler alloys.The formation of the L21 phase of Co2Cr1-xFexAl by the mechanical alloying method was investigated.The effect of Fe doping on the structural and magnetic properties of the samples was also studied.The results were compared with the Slater Pauling prediction.A comparison between these samples and those prepared by the arc-melting method in the literature was made.An increase of the coercivity H c with the increasing Fe doping level was observed.This phenomenon was explained by the increases of lattice strain and magnetic anisotropy with the increasing Fe content.     

Mössbauer comparative study of Fe–Si (3.5 wt%) alloys produced by melting and by mechanical alloying

Mössbauer spectroscopy and X-ray diffraction measurements were done on Fe–Si (3.5 wt%) alloys produced by melting and by mechanical alloying during 15, 30, 50 and 75 milling hours from over 99% purity powders. The Mössbauer spectra were fitted using hyperfine field distribution and it was obtained for all the samples in three ferromagnetic sites with fields of 27, 30 and 33 T for the mechanical alloyed samples and 26.8, 30.13 and 32.83 T for the commercial sample. These three sites are attributed to the pure Fe, Fe with one Si in the next near neighbor (nnn) and Fe with two Si in the nnn. As the milling time increases, the mean field increases too. X-ray diffraction measurement shows that all the samples are BCC, with a lattice parameter that increases with the milling time. These lattice parameters are bigger than that of the commercial alloy.     

Nanocrystalline Fe/Zr alloys: preparation by using mechanical alloying and mechanical milling processes

Nanocrystalline Fe/Zr alloys have been prepared after milling for 9 h the mixture of elemental Fe and Zr powders or the arc-melting produced Fe₂Zr alloy by using mechanical alloying and mechanical milling techniques, respectively. X-ray and Mössbauer results of the Fe and Zr powders, mechanically alloyed, suggest that amorphous Fe₂Zr phase and $\upalpha$ -Fe(Zr) nanograins have been produced with relative concentrations of 91% and 9%, respectively. Conversely, the results of the mechanically milled Fe₂Zr alloy indicate that nanograins of the Fe₂Zr alloy have been formed, surrounded by a magnetic inter-granular phase that are simultaneously dispersed in a paramagnetic amorphous phase.     

Comparative Study by MS and XRD of Fe50Al50 Alloys Produced by Mechanical Alloying, Using Different Ball Mills

In this work we report a comparative study of the magnetic and structural properties of Fe₅₀Al₅₀ alloys produced by mechanical alloying using two different planetary ball mills with the same ball mass to powder mass relation. The Fe₅₀Al₅₀ sample milled during 48 h using the Fritsch planetary ball mill pulverisette 5 and balls of 20 mm, presents only a bcc alloy phase with a majority of paramagnetic sites, whereas that sample milled during the same time using the Fritsch planetary ball mill pulverisette 7 with balls of 15 mm, presents a bcc alloy phase with paramagnetic site (doublet) and a majority of ferromagnetic sites which include pure Fe. However for 72 h of milling this sample presents a bcc paramagnetic phase, very similar to that prepared with the first system during 48 h. These results show that the conditions used in the first ball mill equipment make more efficient the milling process.