Three-dimensional Micro-forming Process of Thin Film Metallic Glass in the Supercooled Liquid Region

2005 ◽  
pp. 37-41
Author(s):  
Seiichi Hata ◽  
Yongdong Liu ◽  
Tomokazu Kato ◽  
Akira Shimokohbe
Keyword(s):  
Thin Film ◽  
Metallic Glass ◽  
Three Dimensional ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
Micro Forming ◽  
Forming Process

Estimation of Micro-Formability and FEM Simulation of Micro-Forming Process of a Zr-Based Bulk Metallic Glass

2007 ◽  
Vol 539-543 ◽  
pp. 2129-2134
Author(s):  
Young Sang Na ◽  
S.G. Kang ◽  
K.Y. Park ◽  
Jong Hoon Lee
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Fem Simulation ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
Micro Forming ◽  
Forming Process ◽  
Rf Values ◽  
Simulation Results

Micro-forming is considered to be a suited technology to manufacture very small metallic parts (several μm~mm). Zr-based bulk metallic glass, Zr62Cu17Ni13Al8, has been expected to be a promising metallic material for micro-forming process due to their isotropy, low flow stress in a wide supercooled liquid region and good stability of amorphous matrix. Therefore, one can expect that micro-forming of Zr62Cu17Ni13Al8 might be feasible at a relatively low stress in the supercooled liquid state without any crystallization during hot deformation. In this study, micro-formability of Zr62Cu17Ni13Al8 bulk metallic glass was investigated for micro-forging of U-shape pattern. Microformability was estimated by comparing Rf values (=Af/Ag), where Ag is corss-sectional area of U groove, and Af the filled area by material. Micro-forging process was also simulated and analyzed by applying the finite element method. The micro-formability of Zr62Cu17Ni13Al8 was increased with increasing load and time in the temperature range of the supercooled liquid state. In spite of the similar trend in the variations of Rf values, FEM simulation results showed much higher Rf values than the experimental Rf values. This disagreement was analyzed based on the stress overshoot phenomena of bulk metallic glasses in the supercooled liquid region. FEM simulation of the microstamping process was applicable for the optimization of micro-forming process by carefully interpreting the simulation results.

Characteristics of Ti-Ni-Zr Thin Film Metallic Glasses / Thin Film Shape Memory Alloys for Micro Actuators with Three-Dimensional Structures

2015 ◽  
Vol 9 (6) ◽  
pp. 662-667 ◽  
Author(s):  
Junpei Sakurai ◽  
◽  
Seiichi Hata
Keyword(s):  
Thin Film ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Metallic Glasses ◽  
Microelectromechanical Systems ◽  
Three Dimensional ◽  
Eutectic Point ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Liquid Region

In this paper, we investigate the characteristics of Ti-Ni-Zr thin film metallic glasses (TFMGs)/ shape memory alloys (SMAs) for microelectromechanical systems (MEMS) applications with three-dimensional structures. The amorphous Ti-Ni-Zr thin films having a Ni content of more than 50 at.% and Zr content of more than 11 at.% undergo glass transitions and are TFMGs. The Ti39Ni50Zr11TFMG has the lowest glass transition temperatureTgof 703 K and a wide supercooled liquid region ΔTof 57 K. Moreover, it has high thermal stability atTg. However, the apparent viscosity of the Ti39Ni50Zr11is higher than those of other Ti-Ni-Zr TFMGs. Moreover, the Ti-Ni-Zr TFMG exhibits higher viscosity than conventional TFMGs because the alloy composition of Ti-Ni-Zr TFMGs/SMAs is far from the eutectic point.

The Effect of Forming Speed on the Formability of a Zr-Based Bulk Metallic Glass

2015 ◽  
Vol 1088 ◽  
pp. 265-271 ◽  
Author(s):  
Wu Xiao ◽  
Jian Jun Li ◽  
Zhi Zhen Zheng ◽  
Jin Yang Li
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Wall Thickness ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Outer Diameter ◽  
Liquid Region ◽  
Forming Process ◽  
Element Analysis ◽  
Extrusion Forming

Taking cup-shaped part (outer diameter D and wall thickness are chosen as 2.2 mm and 0.05 mm, respectively) as an example, the micro-back-extrusion forming process of a Zr55Cu30 Al10Ni5 bulk metallic glass (BMG) in its supercooled liquid region was studied by using finite-element analysis (FEM) and experiment. The effect of forming speed on the formability was analyzed based on the extrusion load, the rheological behavior of the material and the microstructure of the formed parts. It was found that while the forming speed is below than 4 μm/s, the extrusion load increases obviously with the increasing in forming speed, otherwise, the BMG will follow non-newtonian flow and the forming load is insensitive to the forming speed. The parts fabricated at 2 μm/s are obviously crystallized due to the long retention time of metallic glasses at high temperature, a higher forming speed is benefit to enhancing the formability if the BMG. On this basis, micro cup-shaped parts with only 0.05 mm in wall thickness are successfully extruded.

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

2005 ◽  
Vol 894 ◽  
Author(s):  
Ryusuke Yamauchi ◽  
Seiichi Hata ◽  
Junpei Sakurai ◽  
Akira Shimokohbe
Keyword(s):  
Thin Film ◽  
Electrical Resistivity ◽  
Metallic Glass ◽  
Plasma Deposition ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
Arc Plasma ◽  
Relative Resistivity ◽  
Sputter Deposited

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.

scholarly journals Effects of Annealing on Enthalpy Recovery and Nanomechanical Behaviors of a La-Based Bulk Metallic Glass

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 579
Author(s):  
Ting Shi ◽  
Lanping Huang ◽  
Song Li
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Structural Relaxation ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
Nanoindentation Measurement

Structural relaxation and nanomechanical behaviors of La65Al14Ni5Co5Cu9.2Ag1.8 bulk metallic glass (BMG) with a low glass transition temperature during annealing have been investigated by calorimetry and nanoindentation measurement. The enthalpy release of this metallic glass is deduced by annealing near glass transition. When annealed below glass transition temperature for 5 min, the recovered enthalpy increases with annealing temperature and reaches the maximum value at 403 K. After annealed in supercooled liquid region, the recovered enthalpy obviously decreases. For a given annealing at 393 K, the relaxation behaviors of La-based BMG can be well described by the Kohlrausch-Williams-Watts (KWW) function. The hardness, Young’s modulus, and serrated flow are sensitive to structural relaxation of this metallic glass, which can be well explained by the theory of solid-like region and liquid-like region. The decrease of ductility and the enhancement of homogeneity can be ascribed to the transformation from liquid-like region into solid-like region and the reduction of the shear transition zone (STZ).

PREPARATION AND CHARACTERIZATION OF AMORPHOUS ALLOY/POROUS SiCBi-CONTINUOUS STRUCTURE COMPOSITE

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1294-1299 ◽  
Author(s):  
YONGLI CHEN ◽  
AIMIN WANG ◽  
HAIFENG ZHANG ◽  
ZHUANGQI HU
Keyword(s):  
Thermal Properties ◽  
Amorphous Alloy ◽  
Three Dimensional ◽  
Amorphous State ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
Continuous Structure ◽  
Porous Sic

A new kind of composite with a bi -continuous structure was produced by pressure infiltrating melt Zr 41.2 Ti 13.8 Cu 12.5 Ni 10 Be 22.5 into porous SiC which was made by powder metallurgy. Microstructure investigations of the composite show that the melt alloy was fully infiltrated into the voids of porous SiC and quenched into amorphous state. Both the amorphous alloy and the porous SiC exhibit a three-dimensional interconnected net structure. The study of thermal properties reveals that the addition of porous SiC reduces the width of supercooled liquid region of the composite. The bi -continuous composite presents 2% plastic strain and ultimate strength of 1250MPa.

Flow Stress and Elongation of Superplastic Deformation in La55Al25Ni20 Metallic Glass

1999 ◽  
Vol 601 ◽  
Author(s):  
Y. Kawamura ◽  
A. Inoue
Keyword(s):  
Flow Stress ◽  
Metallic Glass ◽  
Strain Rate ◽  
Superplastic Deformation ◽  
Constant Strain Rate ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Liquid Region ◽  
Elongation To Failure ◽  
Crosshead Velocity

AbstractWe have investigated the flow stress and elongation of superplastic deformation in a La55Al25Ni20 (at%) metallic glass that has a wide supercooled liquid region of 72 K before crystallization. The superplasticity that appeared in the supercooled liquid region was generated by the Newtonian viscous flow that exhibits the m value of unity. The elongation to failure was restricted by the transition of the Newtonian flow to non-Newtonian one and the crystallization during deformation. We succeeded in establishing the constitutive formulation of the flow stress in the supercooled liquid region. Its formulation was expressed very well by a stretched exponential function σflow=Dε exp(H*/RT) [1-exp(E/{ε exp(H**/RT)}0.82)]. Formulations describing the elongation to failure in constant-strain-rate and constant-crosshead velocity tests were, moreover, established. It was found from the simulation that the maximum elongation in the constant-strain-rate test reached more than 106% which was two orders of magnitude larger than that in the constant-crosshead-velocity test.

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