Composition Of Amorphous Alloys Research Articles

In situ high-energy X-ray diffraction studies of deformation-induced phase transformation in Ti-based amorphous alloy composites containing ductile dendrites

The deformed-induced microstructure evolution and phase transformation behavior of Ti-based amorphous alloy composites (AACs) containing ductile dendrites in situ formed during solidification were investigated using ex situ transmission electron microscopy (TEM) and in situ high-energy X-ray diffraction (HE-XRD). In situ synchrotron-based HE-XRD experiments provide clear evidence on the deformation-induced phase transformation from β to α″ martensite initiated already in the linear elastic stage of the macroscopic stress–strain curve. Detailed analyses from the diffraction experiments show that the grains that were aligned with [001]β along the loading direction (LD) were then easily transformed into α″ martensite, whereas the martensitic variants oriented with [100]α″ along LD were preferentially formed under compression. The current study provides quantitative information about changes in various microstresses between the crystal phase and the amorphous matrix during deformation. Enhancement of the macroscopic plasticity of the AACs was mainly attributed to the strain relaxation in the β phase and to the formation of multiple shear bands in the amorphous matrix triggered by the deformation-induced phase transformation inside β, knowledge of which greatly deepens understanding of the complex micromechanical behaviors in advanced AACs.

A Cu-based bulk amorphous alloy composite reinforced by carbon nanotube

Bulk Cu50Zr40Ti10 amorphous alloy composites reinforced with carbon nanotube (CNT) were successfully fabricated by hot pressing technique. Their density, thermal conductivity, and mechanical properties were systemically investigated. The density and the compression strength of the compacts both decrease with increasing CNT content. The thermal conductivity of the compacts decreases when the CNT content is less than 0.10% or exceeds 0.60% (mass fraction), while increases when the CNT content is in the range of 0.1%–0.6%. The strain limit and the modulus of the compacts are obviously improved when the CNT content is less than 1.0% and then decrease significantly when the CNT content exceeds 1.00%. The optimum CNT addition is less than 0.20% at the comprehensive properties point of view.

Mössbauer Study of Annealed Fe/Sn Multilayer

[Fe(35 A)/Sn(45 A)]60 multilayer film have been prepared by a vacuum evaporation method, followed by an annealing treatment in vacuum at different temperatures going until 641 K for 3 h. This multilayer has been studied by 57Fe Mossbauer spectrometry at room temperature; it shows that we have formation of defined compound FeSn with thickness 11 A at the interface between the temperatures 588 and 641 K. For the temperature below 598 K, we noticed an increase in the proportion and composition of the nonmagnetic amorphous alloy when the annealing temperature increases. Mossbauer spectroscopy also shows that the Fe in the multilayer is in a α-Fe state.

Electrical, thermal, and mechanical properties of Cu50Zr40Ti10 bulk amorphous composite

Abstract Cu 50 Zr 40 Ti 10 amorphous alloy powder and Cu 60 Zr 30 Ti 10 plate-like ultrafine alloy powder were prepared by gas-atomization and ball-milling methods, respectively. Cu 50 Zr 40 Ti 10 bulk amorphous alloy (BAA) composites reinforced by Cu 60 Zr 30 Ti 10 alloy powder were fabricated by hot pressing method. The matrix of the composites remains a fully amorphous phase after consolidation process. The Cu 50 Zr 40 Ti 10 BAA composites exhibit improved plasticity and dramatically improved electrical and thermal properties by the Cu 60 Zr 30 Ti 10 powder addition. However, the density and compression strength of the BAA composites decrease with the increasing amount of Cu 60 Zr 30 Ti 10 alloy powder.

Ballistic Impact Properties of Zr-Based Amorphous Alloy Composites Reinforced with Woven Continuous Fibers

This study aims at investigating ballistic impact properties of Zr-based amorphous alloy (LM1 alloy) matrix composites reinforced with woven stainless steel or glass continuous fibers. The fiber-reinforced composites with excellent fiber/matrix interfaces were fabricated without pores and misinfiltration by liquid pressing process, and contained 35 to 41 vol pct of woven continuous fibers homogeneously distributed in the amorphous matrix. The woven-STS-continuous-fiber-reinforced composite consisted of the LM1 alloy layer of 1.0 mm in thickness in the upper region and the fiber-reinforced composite layer in the lower region. The hard LM1 alloy layer absorbed the ballistic impact energy by forming many cracks, and the fiber-reinforced composite layer interrupted the crack propagation and blocked the impact and traveling of the projectile, thereby resulting in the improvement of ballistic performance by about 20 pct over the LM1 alloy. According to the ballistic impact test data of the woven-glass-continuous-fiber-reinforced composite, glass fibers were preferentially fragmented to form a number of cracks, and the amorphous matrix accelerated the fragmentation of glass fibers and the initiation of cracks. Because of the absorption process of ballistic impact energy by forming very large amounts of cracks, fragments, and debris, the glass-fiber-reinforced composite showed better ballistic performance than the LM1 alloy.

Thermodynamic assessment and the composition prediction of amorphous alloy in the Fe–B–Er alloy system

The phase diagrams and thermodynamic properties in the Fe–Er and B–Er binary systems have been assessed by using the CALPHAD ( Calculation of Phase Diagrams) method on the basis of the experimental data including the thermodynamic properties and phase equilibria. The thermodynamic parameters of each phase in the Fe–Er and B–Er binary systems were obtained, and an agreement between the calculated results and experimental data was obtained in each binary system. The isothermal sections at different temperatures and liquidus surface in the Fe–B–Er system have been calculated based on the binary thermodynamic data assessed in the present work. In addition, by considering that the glass formation composition of amorphous alloy is closely relative to the eutectic point in corresponding phase diagram, the investigation of glass-forming ability (GFA) in Fe-rich alloys in the Fe–B–Er liquidus surface has also been implemented in this work. The experimental result indicates that the GFA of a certain alloy is intimately relative to its location in the phase diagram, which proves that the phase diagram is an efficient tool for the composition design of Fe-based amorphous alloy.

Study on Amorphous Formation Ability of Al-Fe Alloy Liquids in Hot Dip Aluminizing

The aluminized layer and the La-aluminized layer on 20 carbons steel were prepared by hot dip aluminizing method, and the microstructure and composition of the layer were investigated through scanning electronic microscopy (SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD) and energy dispersive spectroscopy (EDS). The results showed that the amorphous phase was found in the surface layer of the hot dip aluminized steel. In order to study the phenomenon, the Al-Fe alloy liquids used in hot dip aluminizing were quickly solidified and slowly solidified respectively. The results showed that the amorphous phase was found in all Al-Fe alloy samples under the condition of the quick solidification. While the amorphous phase was only found in Al-Fe alloy sample with La under the condition of the slow solidification. Moreover, the pure amorphous alloy exists in the parts region of the sample, and the weight percentages of Al and Fe in pure amorphous alloy was 23: 2, and the amorphous alloy composition also contains a small quantity La. The formation mechanisms of the amorphous phase and behavior of La in the hot dip aluminized layer were also discussed.

Zr–Cu–Ni–Al bulk metallic glasses with superhigh glass-forming ability

Zr–Cu–Ni–Al quaternary amorphous alloy compositions with varying glass-forming ability are developed by an efficient method of proportional mixing of binary eutectics. The critical diameter of the glassy sample is improved from 6 mm for Zr 53Cu 18.7Ni 12Al 16.3 to 14 mm for Zr 50.7Cu 28Ni 9Al 12.3 by straightforwardly adjusting the eutectic unit’s coefficients. The drastic improvement in GFA is attributed to balancing the chemical affinities of the Zr, Cu, Ni and Al components in the melt prior to solidification which makes the precipitation of competing crystalline phases more difficult. As the glass-forming ability increases, the concentration of Cu in the alloys exhibits a same trend. Based on synchrotron radiation high-energy X-ray diffraction analysis and Miracle’s structural model, it is envisioned that the substitution of additional Cu atoms for Zr atoms in the investigated alloys stabilizes the efficient cluster packing structure of the amorphous alloys, leading to the pronounced increase in their glass-forming ability.

Microstructure and Mechanical Properties of Two Continuous-Fiber-Reinforced Zr-Based Amorphous Alloy Composites Fabricated by Liquid Pressing Process

The feasibility to fabricate the tungsten and STS-fiber-reinforced amorphous alloy matrix composites was verified by analyses of the thermal stress and cooling behavior between matrix and metallic fibers. Approximately 50 to 65 vol pct of fibers were homogeneously distributed inside the amorphous matrix, although the matrix of the STS-fiber-reinforced composite contained a small amount of crystalline phases. The compressive test results indicated that the tungsten-fiber-reinforced composite was not fractured at one time after reaching the maximum compressive strength of 2060 MPa, but showed some ductility as the compressive load was sustained by fibers. The STS-fiber-reinforced composite showed the maximum strength of about 1050 MPa, and its strength maintained over 800 MPa until reaching the strain of 40 pct. Both tungsten and STS fibers favorably affected the strength and ductility of the composites by interrupting the propagation of shear bands formed in the amorphous matrix, by dispersing the stress applied to the matrix, and by promoting deformation mechanisms such as fiber buckling. These findings confirmed the possibility to apply the continuous-fiber-reinforced amorphous alloy matrix composites to structural materials requiring excellent properties.

Heterogeneous nucleation of amorphous alloys on catalytic nanoparticles to produce 2Dpatterned nanocrystal arrays

Templates are widely used to produce artificial nanostructures. Here, laser-assistedself-organization has been used to form one- and two-dimensional (D) nanoarrays of Cunanocrystals. Using these nanoarrays as a template, a 2D patterned ferromagneticnanostructure of FeCrSi nanocrystals has been produced by heterogeneousnucleation and growth of nanocrystals by partial devitrification from an amorphousFe64.5Cr10Si13.5B9Nb3 alloy with the Cu nanoparticles acting as catalytic nucleation sites. The interactionamong the ferromagnetic nanocrystals via the residual amorphous matrix canbe controlled by suitable choice of the amorphous alloy composition. Althoughdemonstrated for a ferromagnetic system, the processing method may have much widerapplicability for producing artificial nanostructures of a wide variety of materials whenmaterials-specific catalysts and amorphous alloy compositions are judiciously chosen.

Thermodynamic prediction of the composition of Fe-based amorphous alloys

The liquidus univariant lines of the Fe-Nb-B ternary system have been thermodynamically calculated by means of CALPHAD method and Fe-based thermodynamic data. It is found that there are two eutectic reactions in the Fe-rich corner, that is, (1) L(Fe-3Nb-15B) → α + γ + M 2B (1430 K), and (2) L(Fe-10Nb-27B) → FeB + Lc 14+ M 2B (1575 K). Moreover, the eutectic points are very close to the compositions with high glass forming ability determined experimentally. This means that it is feasible to design the compositions of multicomponent bulk metallic glasses by looking for the eutectic points in the Fe-Nb-B system by means of thermodynamic calculation.

Employment of the artificial neural networks for prediction of magnetic properties of the metallic amorphous alloys

The aim of this work is to employ the artificial neural networks for modelling the magnetic properties of the amorphous alloys with the iron and cobalt matrix. The artificial neural networks implemented in StatSoft Statistica Neural Network PL 4.0F were used to determine the relationship between the chemical compositions of amorphous alloys, heat treatment parameters and magnetic properties. The attempt to use the artificial neural networks for predicting the effect of the chemical composition and heat treatment parameters on the magnetic flux density BS succeeded, as the level of the obtained results was acceptable, as the level of the obtained results was acceptable. For different magnetic properties of soft magnetic materials, further calculations are planned. The results of calculation makes it possible to design new advantageous combinations of concentrations of the particular elements to develop grades of the soft magnetic alloys. This paper employs the artificial neural networks for modelling chemical composition and heat treatment parameters of amorphous soft magnetic alloys to obtain the best magnetic properties. [Received 15 August 2007; Accepted 20 October 2007]

Composition dependent ductility in the amorphous Zr–Ti–Ni–Cu–Be alloy system

This work maps the bending ductility versus composition of amorphous alloys in the Zr–Ti–Ni–Cu–Be system. Alloys with a Zr:Ti ratio of 5.67:1 show higher ductility and thermal stability over a wider composition range than those with a Zr:Ti ratio of 3:1. The loss of ductility occurs in alloys that have compositions near those of quasicrystal or intermetallic phases, which form in the amorphous matrix upon cooling.

Amorphous-FeCoCrZrB ferromagnets for use as high-temperature magnetic refrigerants

Magnetic metallic glasses, having large magnetic moments and high Curie temperatures (TC), have not been widely studied as magnetic refrigerants. In this study, we report on the magnetocaloric effects of five FeCoCrZrB amorphous alloys [(FexCoyCrz)91Zr7B2, with Fe:Co:Cr ratios of 100:0:0, 90:15:5, 85:5:10, and 75:15:10] chosen for efficiently surveying the high TC metallic glass composition surface. Magnetic isotherms were measured at 25K intervals from 25to525K. The entropy change (ΔS) due to the magnetocaloric effect was computed by integrating the magnetic isotherms. The refrigeration capacity (RC) was computed by Wood-Potter method. At 3979kA∕m (50kOe) the FeCoCrZrB alloys have RC values of 240–320J∕kg; at 796kA∕m (10kOe) the alloys have values of 32–54J∕kg. The RC values favorably compare with values reported for other refrigerant materials. The peak ΔS temperature depends strongly on composition, varying from 200to450K. The wide flexibility in choosing amorphous alloy compositions allows them to be fine tuned for multistage high temperature refrigerators. The saturation magnetization at 25 and 300K and Curie temperatures are also reported for the five alloys.

Mechanical Behavior of Bulk Amorphous Alloys Reinforced by Ductile Particles at Cryogenic Temperatures

The mechanical behavior of Zr-based bulk amorphous alloy composites (BAACs) was investigated at 77 K. The 5 vol. % Ta-BAAC maintained large plastic strains of approximately 13% with a 16% strength increase, when compared with that at 298 K. The interaction between shear bands and particles shows that shear extension in particles has limited penetration, and shear bands build up around particles. In addition to on the failure surface of the amorphous matrix, molten characteristics were also found on the surface of sheared particles. Pair distribution function studies were performed to understand the mechanical behavior.

Combinatorial Arc Plasma Deposition of Thin Films

In this paper, we introduce a new combinatorial thin film deposition process that uses arc plasma [combinatorial arc plasma deposition (CAPD)]. The major goal of CAPD in this study is to search for new compositions of amorphous thin film alloys. CAPD uses three cathodic arc plasma guns and the guns shoot the pulse like plasma one by one at a specific time interval. The plasma from each gun is guided onto a substrate by a magnetic field at a specific area on the substrate so as to deposit a compositionally-graded thin film. The deposited thin film is separated into 1,089 samples (the size of each is 1 ×1 mm2) by a trench grid on the substrate. The samples together are called the thin film library and all samples are numbered by the 5-bit row and column marks in the grid. To prove CAPD, a thin film library of a Pd–Cu–Si alloy system was deposited. The composition and non crystallinity of 180 samples were evaluated using energy-dispersive X-ray fluorescence spectrometer (EDX) and imaging-plate X-ray diffractometer (IP-XRD), respectively. Both measurements were performed without detaching the samples from the library. Analysis of 180 samples showed a graded composition, and some of the samples were shown to be amorphous.

Cathodic Arc Plasma Combinatorial Material Synthesis for Composition Search of New Amorphous Alloy

AbstractCombinatorial arc plasma deposition (CAPD) method was used to search for new compositions of thin film amorphous alloys. A cathodic arc plasma gun (APG) was adopted as the deposition source for CAPD. The CAPD setup has three APGs radiating out from the center of a substrate. The APGs shoot pulse-like plasma shots one by one at a specific time interval. The plasma from each APG cathode is guided onto a specific area on a substrate by a magnetic field. Each such area overlaps the adjacent ones. Thus, a compositionally-graded thin film is deposited in the overlap area because of mixing of each deposited thin film from each APG that has a thickness grade. The deposited thin film is separated into 1,089 samples (the size of each is 1×1 mm2) using a grid on the substrate. The samples together are referred to as the thin film library. To demonstrate the capability of CAPD, two thin film libraries were deposited in this study. One is a thin film library of a PdCuSi alloy system, and the other is a MoZrPd system. The compositions and crystallinity of the samples were evaluated on the substrate using EDS and IP-XRD respectively. Analysis of the samples showed a graded composition, and some of the samples were shown to be amorphous in both libraries.

Effects of exchange interaction in bilayer DyxCo1−x /NiFe films in the vicinity of compensation compositions of amorphous DyCo alloys

The displacement field of the hysteresis loop due to exchange anisotropy in planar DyCo/NiFe systems is studied experimentally as a function of the concentration of the rare-earth element. The bilayer DyCo/NiFe film system is characterized by an orthogonal arrangement of the effective magnetizations of separate layers under the condition that the amorphous DyCo layer is prepared in the region of magnetic compensation. An analysis of the dependence of the displacement field on the Dy concentration has led to an understanding of the physical mechanism of the formation of the exchange anisotropy in these planar systems.

Formation and crystallization of Al–Ni–Ti amorphous alloys

Abstract Formation and crystallization behaviors of the Al–Ni–Ti amorphous alloys have been investigated in the present study. Among the amorphous alloy compositions investigated in the present study, only Al 87.5 Ni 10 Ti 2.5 alloy composition exhibits a good ductility, i.e. 180° bending without fracture, indicating that the ductility of the Al–Ni–Ti amorphous alloys is strongly dependent on the alloy composition. Improved ductility can be obtained only when a few nanometer size Al crystals are embedded in the amorphous matrix. The amorphous Al–Ni–Ti alloys crystallize by either primary crystallization of nanometer-sized fcc-Al phase or by the simultaneous precipitation of fcc-Al and metastable intermetallic compound. The Al–Ni–Ti amorphous alloy showing the bending ductility crystallizes by diffusion-controlled growth of quenched-in Al crystals. On the other hand, the Al–Ni–Ti amorphous alloy without bending ductility crystallizes by diffusion-controlled nucleation and growth process.

Effect of strain rates on the fracture morphologies of Zr-based bulk metallic glasses

The effect of strain rates from 1 × 10 −4 s −1 to 2 × 10 3 s −1 on tensile fracture morphologies of Zr 52.5Al 10Ni 10Cu 15Be 12.5, Zr 65Al 10Ni 10Cu 15, and Zr 52.5Al 10Ni 14.6Cu 17.9Ti 5 bulk amorphous alloys was investigated by scanning electron microscopy. The results show that the tensile fracture morphologies of three compositions of bulk amorphous alloys are dependent on strain rate. At low strain rates, the tensile fracture surface morphology of Zr-based bulk metallic glasses presents cleavage veins. However, the morphology will become microvoid-coalescence dimples when the strain rate is high enough.