Thin Film Metallic Glasses Research Articles

PRE-10 DESIGN AND FABRICATION ON A NOVEL TRAVELING WAVE TYPE CYLINDRICAL ULTRASONIC LINEAR MICROACTUATOR(MM/Micro/Nano Precision Equipments IV,Technical Program of Oral Presentations)

A piezoelectric ultrasonic microactuator is presented, with a cylindrical stator and slider structure. The length and diameter of the microactuator are about 10 and 1.5 mm, respectively. The stator consists of two piezoelectric ceramic (PZT) tubes connected by a thin film metallic glass (TFMG) pipe, which is fabricated using the rotating magnetron sputtering technique. Traveling wave propagation is generated on the TFMG pipe in finite element method (FEM) simulations. Bi-directional motion of the slider was observed successfully around 600 kHz, and the maximum velocity was about 40 mm/s at 25 V.

Laser Forming of Thin Film Metallic Glass

Palladium based thin film metallic glasses were plastically bent by laser forming process. Thin films of Pd77Cu6Si17 with a thickness of 0.028mm and Pd40Ni40P20 with a thickness of 0.017mm were used for specimen. A 50W YAG laser was employed for forming. Variation of bending angle was investigated by changing working conditions such as laser power, laser operation mode (continuous wave and Q-switch pulsed modes), Q-sw frequency, scanning velocity and scanning number. From the experimental results, both thin films of Pd77Cu6Si17 and Pd40Ni40P20 were successfully bent for more than 85o. The formed thin films did not crystallize but were amorphous. As scanning number increased, bending angle also increased but increasing rate decreased. When laser power and scanning velocity were changed, bending angle had a peak. When Q-sw frequency was changed, bending angle had a broad peak in Pd77Cu6Si17 case, but that was larger as frequency was smaller in Pd40Ni40P20 case.

Characteristic studies on the Zr-based metallic glass thin film fabricated by magnetron sputtering process

The Zr61All7.5Ni10Cu17.5Si4 amorphous alloy (ZrAlNiCuSi) was selected as the target material for preparing a series of thin film coatings on the 304 stainless steel substrate by magnetron sputtering process. The microstructure of these as-prepared ZrAlNiCuSi and (ZrAlNiCuSi)N thin films were examined by X-ray diffraction and TEM observation. In parallel, the properties characterization of these ZrAlNiCuSi and (ZrAlNiCuSi)N alloy thin films including hardness measurement by nano indentation, wetting ability by contact angle measurement, adhesion capability by scratch test, surface roughness analyzed by atomic force microscopy (AFM) and the wear resistance evaluated by pin-on disc method were investigated and compared to the commercial hard coatings. The results revealed that all of these ZrAlNiCuSi and (ZrAlNiCuSi)N thin films present a typical amorphous microstructure and smooth surface with roughness about 1 nm. This feature makes these amorphous ZrAlNiCuSi and (ZrAlNiCuSi)N thin films posses a lower wettability as well as a higher wear resistance.

2101 コンビナトリアル手法によるMEMS用新材料の探索(要旨講演,一般セッション:マイクロナノメカトロニクス)

A new combinatorial method to deposit metallic thin films using an arc plasma, combinatorial arc plasma deposition (CAPD), was applied to search for novel compositions of thin film metallic glasses (TFMGs) as new MEMS materials. The CAPD setup includes three arc plasma guns (APGs). with each gun shooting a pulse-like plasma of constituent elements at specific time intervals to deposit a compositionally-graded metallic thin film on an SiO_2 substrate. First, a Pd-based compositionally-graded thin film was deposited to search for the lowest resistivity composition of Pd-Cu-Si TFMGs. As the result, the Pd_<81>Cu_5Si_<14> at.% sample showed the lowest absolute resistivity of 64 μΩ・cm and a supercooled liquid region (SCLR) temperature range (ΔTx = Tx - Tg) of 50K. Next, we found out a novel Ru-Zr-Al TFMG by CAPD. Differential scanning calorimetry revealed that the two sputter-deposited samples Ru_<65>Zr_<30>Al_5 and Ru_<67>Zr_<25>Al_8 had a SCLR. Moreover, the samples exhibited superior mechanical properties.

Behavior of joining interface between thin film metallic glass and silicon nitride at heating

Thin film metallic glass is usually deposited directly on a substrate. The strength of the adhesive join between the substrate surface and the thin film metallic glass is important for fabrication of micro- and/or nano-electromechanical systems. The strength of the join is especially affected by the stresses at the interface, created by the thermal history during the fabrication process and/or during use. In the present study, a bimetallic cantilever of silicon nitride film with a Pd-based thin film metallic glass was fabricated and heated under vacuum in order to generate high stresses at the joining interface. The behavior at the interface were observed and analyzed in terms of the projected length of the cantilever.

Combinatorial arc plasma deposition search for Ru-based thin film metallic glass

We have discovered a novel Ru-based thin film metallic glass (TFMG) using combinatorial arc plasma deposition (CAPD). To search for Ru-based TFMG, alloy systems of Ru–Zr–Al, Ru–Zr–Fe and Ru–Zr–Mo were investigated by making libraries. Each library consisted of 1089 CAPD samples deposited on a substrate by CAPD. Composition of each sample is different with each other. The composition and phases of the CAPD samples were measured by energy dispersive X-ray fluorescence spectrometry and X-ray diffractometry, respectively. Results showed the amorphous regions depended on the additive elements Al, Fe or Mo. Compared with the addition of Al, the addition of Fe or Mo exhibited high amorphous forming ability. To evaluate the mechanical properties, the glass transition temperature T g and the crystallization temperature T x of the amorphous samples in each Ru–Zr–X alloy, larger samples having the same compositions as the typical amorphous CAPD samples were reproduced by sputtering because the CAPD samples were too small to measure the mechanical properties, T g and T x. Ru 65Zr 30Al 5 and Ru 67Zr 25Al 8 samples were found to exhibit the better fracture stress and elastic limit than conventional TFMGs, while Ru–Zr–Fe and Ru–Zr–Mo samples were found to be brittle. DSC revealed that the Ru 65Zr 30Al 5 sample was a TFMG, with a T g of 902 K and T x of 973 K.

Searching for Novel Ru-Based Thin Film Metallic Glass by Combinatorial Arc Plasma Deposition

We found out a novel Ru–Zr–Al thin film metallic glass by combinatorial arc plasma deposition (CAPD). To search for Ru-based thin film metallic glasses, first, a library of 1,089 CAPD samples was deposited, of which fifteen amorphous samples were selected by X-ray diffractometry. The compositions of these samples were measured by energy dispersive X-ray fluorescence spectrometry. From the fifteen samples, two samples having low Al content (Ru65Zr30Al5 and Ru67Zr25Al8, at. %) were chosen, and their compositions were reproduced in samples deposited by sputtering, because the CAPD samples were too small for evaluating the glass transition temperature Tg and crystallization temperature Tx by differential scanning calorimetry (DSC). DSC revealed that the two sputter-deposited samples Ru65Zr30Al5 and Ru67Zr25Al8 had a supercooled liquid region (SCLR), showing a Tg, Tx, and width of SCLR ΔTx (=Tx-Tg) of 902, 973, and 71 K in the case of Ru65Zr30Al5, and 913, 979, and 66 K in the case of Ru67Zr25Al8, respectively. Moreover, the sputter-deposited samples Ru65Zr30Al5 and Ru67Zr25Al8 exhibited superior mechanical properties. The fracture stress σf, elastic limit εl, and Young's modulus E were 1.9 GPa, 2.0% and 92.7 GPa, respectively, for Ru65Zr30Al5 and 1.9 GPa, 2.0%, and 91.6 GPa, respectively, for Ru67Zr25Al8.

Plasma sputtering of an alloyed target for the synthesis of Zr-based metallic glass thin films

ZrTiAlCuNi films are deposited by plasma sputtering from an alloyed target prepared by induction – cold crucible melting method. The films are found to be amorphous and exhibit a composition very similar to the target one. It is shown that the amorphous character of the deposits is rather due to the high glass forming ability (GFA) of the Zr-based alloy system, than to the deposition method used. The sputtering process of the alloyed target, composed of mixed Zr-containing phases, has been studied. It appears to be a global process leading to a quasi-congruent transfer of the target elements into the film.

Combinatorial Search for Low Resistivity Pd–Cu–Si Thin Film Metallic Glass Compositions

A new combinatorial method to deposit thin films using an arc plasma, Combinatorial arc plasma deposition (CAPD), was applied to search for low resistivity compositions of Pd–Cu–Si thin film metallic glasses (TFMGs). The CAPD setup includes three arc plasma guns (APGs), with each gun shooting a pulse-like plasma of Pd, Cu or Si at specific time intervals to deposit a Pd–Cu–Si thin film on an SiO2 substrate. In this study, a Pd-based compositionally-graded thin film was deposited by controlling the number of shots as well as the plasma strength. The deposited thin film was separated into 1,089 samples (thin film library), and the thickness, composition, phase, and relative resistivity of each sample was evaluated without detaching them from the library. From the samples, three amorphous, low relative resistivity CAPD samples were identified. To verify that these samples were metallic glasses, their compositions were reproduced in samples deposited by sputtering, and their Tg (glass transition temperature) and Tx (crystallization temperature) were measured. The absolute resistivities of the three metallic glass samples were also measured. As the result, the Pd81Cu5Si14 at. % sample showed the lowest absolute resistivity of 64 µ Ω ·cm and a supercooled liquid region temperature range ( ΔTx=Tx-Tg) of 50 K. This resistivity is 17% lower and the supercooled liquid region is almost two times larger than those of the known Pd-based TFMG composition.

Simulations of nanoindentation in a thin amorphous metal film

Nanoindentation was simulated in a two dimensional model metallic glass thin film using molecular dynamics. Strain localization was observed in simulations where the system was sufficiently structurally relaxed prior to deformation. Indentation simulations utilized an atomic indenter that adhered to the surface or a frictionless indenter. Boundary conditions were varied to constrain the film or allow the film to relax in-plane to examine the effect on shear band formation. The most constrained system, i.e. that with the atomic indenter and the constrained boundaries exhibited the highest hardness.

Preface to the viewpoint set on mechanical behavior of metallic glasses

This work reports the use of a new high-temperature scanning indentation (HTSI) technique to monitor the physical changes occurring in thin-film metallic glasses (TFMGs) in situ during heat treatment at the local scale. Using this technique, based on high-speed nanoindentation performed during thermal cycles, the entire mechanical evolution with temperature of a binary model ZrCu TFMG was characterized in only a few hours. This approach enabled clear identification of the physical evolutions of the amorphous coatings in only one indentation experiment, highlighting in particular the metallic glass-to-supercooled liquid transition and crystallization process. In addition, the brittle-to-ductile transition was precisely characterized, with remarkable agreement with the literature. Moreover, the mechanical response of the ZrCu thin film was assessed in situ throughout the entire supercooled liquid stage, providing key kinetic information. Nanohardness measurements also enabled the crystallization fraction to be computed over time during the crystallization process. In addition, differential scanning calorimetry and high-temperature X-ray diffraction were performed for comparison purposes, with excellent agreement with the HTSI results. Through this model out-of-equilibrium thin-film study, both the efficiency and robustness of HTSI were demonstrated, providing a better understanding of the thermally activated mechanisms of small-scale systems.

Nonchalcogenide Inorganic Blue Laser Recordable Medium

A new nonchalcogenide inorganic blue laser recordable disk was successfully developed using a Pd-based metallic glass, which transformed from the amorphous state to the crystalline state upon laser irradiation. The optical properties and thermal properties of the Pd-based metallic glass thin film were studied. A recordable optical disk was prepared with a simple disk structure, which included only a dielectric layer and a recording layer, for an optical system based on a blue-violet laser diode and an objective lens with a high numerical number (NA) of objective lens of 0.85. The recording performance of the blue laser recordable disk was evaluated. The readout stability and archival lifetime were verified for the blue laser recordable disk.

2313 薄膜金属ガラスを用いた集積形ERマイクロアクチュエータ(OS8-3 アクチュエータシステム(3))

A novel 3-DOF ER micractuator using thin film metallic glass was proposed and fabricated. The actuator consists of 3-DOF stacked diaphragms and a micro ER valves unit. By internal stress elimination in the supercooled liquid region and wide elastic range of thin film metallic glass, the diaphagms have capability to generate large displacement. In this paper, as a simple diaphagm configulation for larger displacement, a double dome diaphragm was obtained based on FEM analysis. Through fabrications using MEMS process, process conditions to fabricate the double dome diaphragms were experimentally clarified. Also, the micro ER valves unit large model was fabricated and the valve control characteristics were experimentally clarified.

Effect of annealing close to Tg on notch fracture toughness of Pd-based thin-film metallic glass for MEMS applications

Notch fracture toughness of Pd-based thin-film metallic glasses, prepared both as-deposited and annealed at 640 K close to the glass transition temperature (Tg = 637 K), was examined by static bending tests. The experimental results show that the notch fracture toughness of thin-film metallic glasses decreased with increasing annealing time at 640 K. The fracture behaviors, the propensity for shear banding, as well as the variation of Youngs modulus of Pd-based thin-film metallic glasses as a function of annealing time, were demonstrated to be correlated with fracture resistance.

Deformation Behavior of Free-Standing Pd-based Thin Film Metallic Glass for Micro Electro Mechanical Systems Applications

chinese acad sci, inst met res, shenyang natl lab mat sci, shenyang 110016, peoples r china. univ utah, dept elect & comp engn, salt lake city, ut 84110 usa. northeastern univ, sch met & mat, shenyang 110004, peoples r china.;zhang, gp (reprint author), chinese acad sci, inst met res, shenyang natl lab mat sci, 72 wenhua rd, shenyang 110016, peoples r china;gpzhang@imr.ac.cn

Nanoscale Patterning of Zr-Al-Cu-Ni Metallic Glass Thin Films Deposited by Magnetron Sputtering

Completely glassy thin films of Zr-Al-Cu-Ni exhibiting a large super-cooled liquid region (deltaTx = 95 K), very smooth surface (Ra = 0.65 nm), and an extremely high value of Vicker's hardness (Hv = 940), as compared to bulk Zr-Al-Cu-Ni metallic glass, were deposited by radiofrequency magnetron sputtering. Nanoscale patterning ability of Zr-Al-Cu-Ni metallic glass thin films was demonstrated by a focused ion beam etching. The capability to write nanometer-scale patterns (line width approximately 12 nm) opens up a variety of possibilities for fabricating nanomolds for imprint lithography, and a wide range of two- or three-dimensional components for future nanoelectromechanical systems.

Atomic dynamics in molecular dynamics simulations of glassy CuTi thin films

We present results on atomic dynamics in metallic glass thin films below the glass transition temperature using molecular dynamics simulations. Thin CuTi films of different compositions are prepared by quenching the liquid to an amorphous state. The atomic dynamics on the amorphous surface and inside the bulk of the samples are quantitatively compared by calculating diffusion constants and jump length distributions. Here, we focus on the collective or single particle character of the diffusion mechanism in dependence of the atom type. In addition, single atom exemplifications are analyzed for the different kinds of atomic dynamics. We find that Cu surface atoms diffuse with a single atom jump dynamics, whereas inside the bulk collective behavior dominates for both species.

Combinatorial Optimization of Low Electrical Resistivity Pd-based Thin Film Metallic Glass

AbstractIn order to optimize low electrical resistivity compositions of Pd-based thin film metallic glass (TFMG), Combinatorial arc plasma deposition (CAPD) was employed. A Pd-based continuous compositionally-graded thin film was deposited using CAPD in the experiments. To deposit the composition-grade of the Pd-rich thin film, the number of shots and the plasma strength were controlled. The deposited thin film was separated into 1,089 samples for measurements. The thickness, composition, phase and relative resistivity of these samples were measured respectively. And three amorphous CAPD samples exhibiting low relative resistivity were selected. To determine whether these were TFMG compositions, their compositions were reproduced on sputter-deposited samples and their Tg and Tx were measured. It was found that the sample of Pd81Cu5Si14 at.% showed the lowest absolute resistivity (60 μΩ·cm) and the largest temperature range of supercooled liquid region (SCLR) i.e., 60 K among all samples. The resistivity was 19% lower than conventional Pd-based TFMG and SCLR was two and half times as large. The tensile strength was higher than the conventional TFMG and the Young's modulus was lower than the conventional one.

On-Chip Variable Inductor Using Microelectromechanical Systems Technology

We have proposed and evaluated the novel three-dimensional on-chip variable inductor that is fabricated using microelectromechanical systems technology. The variable inductor was made of thin film metallic glass, Pd76Cu7Si17, that has high flexibility. Since the thin film metallic glass has high elasticity, the height of the three-dimensional spiral inductor can be changed, resulting in the change of inductance. The fabricated inductor has the inductance of 3.64–3.74 nH due to the change in the spiral height with a Q-factor of 2.0 at 2 GHz. The variable range of inductance is 0.1 nH, and the ratio is 3%. Simulation results have shown that the Q-factor is increased by coating with a low-resistivity metal; when the inductor is coated with Au, the Q-factor is increased to 7.2 at 2 GHz. Furthermore, the several-nH inductor with a variable range of 10% is designed.

Integrated conical spring linear actuator

This report details an electrostatic microactuator called the conical spring linear actuator (CSLA) which is capable of stepwise displacement vertical to the substrate. The CSLA has a moving electrode of three-dimensional conical spring shape which is placed on four base electrodes. The conical spring shape is constructed of a thin film metallic glass (TFMG) which is a new material for MEMS. TFMG is a kind of amorphous alloy and softens in a temperature range referred to as the supercooled liquid region (SCLR). The TFMG can be deformed easily into 3D forms at the SCLR. A new fabrication process is introduced which is appropriate for the integration of CSLA and the experimental driving of the integrated CSLA. The integrated CSLA exhibits 200 μm total stepwise displacement vertical to the substrate.