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Synthesis of metallic glass composites using phase separation phenomena
H.J. Changa, 1, W. Yookb, E.S. Parkc, J.S. Kyeongb and D.H. Kimb
a Division of Humantronics Information Materials, Yonsei University, 134 Shinchondong, Seodaemungu, Seoul 120-749, Republic of Korea
b Center for Non-Crystalline Materials, Department of Metallurgical Engineering, Yonsei University, 134 Shinchondong, Seodaemungu, Seoul 120-749, Republic of Korea
c Department of Materials Science and Engineering, College of Engineering, Seoul National University, Seoul 151-744, Republic of Korea
Received 2 September 2009; revised 4 December 2009; accepted 16 December 2009. Available online 27 January 2010.
Abstract
Phase separation phenomena in metallic glass systems have been explored by thermodynamic calculation and experimental method in the present study. Miscibility gap and spinodal curve for liquid phase in Gd–Ti–Al–Co/Cu systems have been calculated using the CALPHAD method. Based on the calculation result, various types of phase separation phenomena have been observed experimentally. Basically two types of structure are observed: interconnected-type structure by spinodal decomposition; and droplet-type structure by nucleation and growth mechanism. Multi-step phase separation occurs during cooling from the liquid, forming a hierarchical length scale composite structure. Depending on the glass-forming ability of the separated liquid phase, amorphous/amorphous or amorphous/crystalline composite structure can be obtained. The present study shows that there are several factors such as critical temperature, asymmetry and composition range of the spinodal curve which affect scale and morphology of the microstructure after phase separation.
Keywords: Metallic glass; Phase separation; Composite; Spinodal decomposition
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Microstructure and Mechanical Properties of Partially Amorphous Al85Y8Ni5Co2 Plate Produced by Spray Forming
V.C. Srivastavaa, b, K.B. Surreddic, S. Scudinoc, M. Schowalterd, V. Uhlenwinkela, A. Schulza, J. Eckertc, e, A. Rosenauerd and H.-W. Zocha
a Institut für Werkstofftechnik, Universität Bremen, Badgasteiner Str. 3, D-28359 Bremen, Germany
b Metal Extraction & Forming Division, National Metallurgical Laboratory, Jamshedpur-831007, India
c IFW Dresden, Institute for Complex Materials, P.O. Box 27 01 16, D-01171 Dresden, Germany
d Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee 1, D-28359 Bremen, Germany
e TU Dresden, Institute of Materials Science, D-01062 Dresden, Germany
Received 12 March 2009; revised 23 December 2009; accepted 19 January 2010. Available online 28 January 2010.
Abstract
A 12 mm thick Al85Y8Ni5Co2 plate was spray deposited on a 30 mm thick copper substrate pre-heated to 383 K. The deposit microstructure consists of an amorphous phase, 50-150 nm fcc-Al grains, 0.2-0.7 μm Al2Y and Al3Y intermetallic phases and some unidentified phases. The hardness of different microstructural features and the compressive strength of the deposit, after extrusion at 723 K, were evaluated. The small size overspray particles as well as the deposit show a glass transition phenomenon. The total crystallization energy of the deposit is 121 J/g compared to 83.9 J/g for the small sized overspray powder, indicating its high metastability. A compressive strength of 925 MPa and a deformation strain of 9% were achieved for the deposit after extrusion. The novel microstructural features in the deposit are attributed to the “chilling effect” on highly undercooled or partially solidified large size droplets during deposition onto the pre-heated substrate, and the rapid heat extraction thereof due to a close contact at the deposit/substrate interface.
Keywords: Spray deposition; Bulk amorphous materials; Al alloys; Hardness; Compressive strength
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Effect of Nb on glass forming ability and plasticity of (Ti-Cu)-based bulk metallic glasses
Z.Y. Suoa, K.Q. Qiua, Q.F. Lia, Y.L. Rena and Z.Q. Hub
a School of Materials Science and Engineering, Shenyang University of Technology, 111 West Shenliao Road, Shenyang 110178, P R China
b Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, P R China
Received 18 June 2009; revised 1 December 2009; accepted 19 January 2010. Available online 28 January 2010.
Abstract
A Ti33Cu47Zr9Ni6Sn2Si1Nb2 bulk metallic glass has been developed by Nb partial substitution for Zr in Ti33Cu47Zr11Ni6Sn2Si1 alloy. The glass forming ability Ti33Cu47Zr9Ni6Sn2Si1Nb2 alloy has been investigated using differential scanning calorimetry and X-ray diffractometry. Partial Nb substitutes for Zr promotes the glass forming ability. Ti33Cu47Zr9Ni6Sn2Si1Nb2 BMG with diameter of 3 mm can be fabricated by Cu-mold injection casting method. The glass forming ability of Ti33Cu47Zr9Ni6Sn2Si1Nb2 alloy is enhanced by stabilizing the undercooled liquid against crystallization. The plastic strain up to 2.5% was obtained for Ti33Cu47Zr9Ni6Sn2Si1Nb2 BMG compared to 0.15% for Ti33Cu47Zr11Ni6Sn2Si1 BMG, which demonstrates that small amount of Nb addition can have a dramatic effect on plasticity enhancement in Ti-Cu-based BMG. The intersection and branching of the shear bands are observed. The plastic strain of the Ti33Cu47Zr9Ni6Sn2Si1Nb2 BMG can be improved by the generation of nanocrystalline particles, which lead to multiple shear bands.
Keywords: Ti-Cu based metallic glasses; Glass forming ability; Mechanical properties
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Effects of drawing on the tensile fracture strength and its reliability of small-sized metallic glasses
Y. Wua, H.H. Wua, X.D. Huia, G.L. Chena and Z.P. Lua
a State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China
Received 3 October 2009; revised 20 December 2009; accepted 22 December 2009. Available online 25 January 2010.
Abstract
The effects of drawing on the structure and mechanical properties of a Co-based metallic glass under tension were thoroughly investigated. Surface changes induced by drawing, including removal of surface flaws, surface chemical homogenization and generation of compressive residual stress tend to increase the fracture strength, whilst open volumes created during drawing, particularly nano-voids, are likely to soften the wires. Initially, the surface changes are decisive factors, but as drawing proceeds, the open volumes gradually become dominant, yielding a maximum fracture strength in the wires with an area reduction ratio of 22%. Moreover, it was found that the fracture strength reliability was enhanced by the drawing, which is due not only to the surface perfection but also to the increase of plastic deformation capability, manifested by the decrease in the activation energy of individual shear transformation zones. Our results imply that the drawing technique could be a promising approach to continuously producing small-sized glassy wires with improved overall properties.
Keywords: Metallic glasses; Drawing; Tension test; Strength reliability
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Correlation between thermodynamics and glass forming ability in the Al–Ce–Ni system
Chengying Tanga, b, Yong Dub, Jiong Wangb, Huaiying Zhoua, Lijun Zhangb, Feng Zhengc, Joonho Leed and Qingrong Yaoa
a Department of Materials Science and Engineering, Guilin University of Electronic Technology, 1 Jinji, Guilin, Guangxi 541004, China
b State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083, China
c Key Laboratory of Non-ferrous Materials of Ministry of Education and School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083, China
d Department of Materials Science and Engineering, Korea University, 5-1 Anam-dong, Seongbuk-gu, Seoul 136-713, Republic of Korea
Received 13 September 2009; accepted 19 December 2009. Available online 25 January 2010.
Abstract
The Al–rich corner of ternary Al–Ce–Ni metallic glass forming system was investigated by a hybrid approach of thermodynamic modeling and first–principles calculations. A consistent thermodynamic data set for the Al–Ce–Ni system was obtained. Based on the correlation between glass forming ability and thermodynamics, we found that there are no deep eutectics in the Al–rich corner. Alloys with high GFA appear in off–eutectic area with heat of mixing ranging from −15 to −49 kJ/mol of atom, and the alloy with a local minimum driving forces show highest GFA according to the melt spinning and copper mold casting experiments and the calculation of driving force for the formation of crystalline phases in the supercooled liquid state. The nucleation driving force is the dominant factor determining the formation of amorphous phases, among several other factors such as heat of mixing, viscosity, and glass transition temperature.
Keywords: A. Ternary alloy systems; B. Thermodynamic and thermochemical properties; B. Metallic glasses; E. Phase diagram, prediction (including CALPHAD); E. Ab initio calculations
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Improved plasticity of bulk metallic glasses upon cold rolling
M.H. Leea, K.S. Leeb, J. Dasc, J. Thomasd, U. Kühnd and J. Eckertd
a Advanced Materials Division, Korea Institute of Industrial Technology, Incheon 406-840, Korea
b Department of Materials Processing, Applied Plasticity Research Group, Korea Institute of Materials Science, Changwon, Gyeongnam 641-831, Korea
c Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur 721 302, West Bengal, India
d Leibniz-Institute IFW Dresden, Institute for Complex Materials, Helmholtzstr 20, D-01069 Dresden, Germany
Received 24 October 2009; revised 10 December 2009; accepted 13 January 2010. Available online 18 January 2010.
Abstract
The intrinsic plasticity of Zr44Ti11Cu9.8Ni10.2Be25 and Zr55Ti5Al10Cu20Ni10 bulk metallic glasses (BMGs) are improved from 0.5% up to 15% plastic strain due to the introduction of microstructural inhomogeneitiesous upon cold rolling at room temperature. This approach shows an easy way of making fragile glasses and to overcomes intrinsic brittleness of the BMGs by modifying their physical properties, which enable easy nucleation and branching of multiple shear bands upon during unconstrained loading during compression test.
Keywords: Bulk metallic glass; short-range order; cold rolling; shear bands; plasticity
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Glass formation enhanced by oxygen in binary Zr-Cu system
Y.X. Wanga, H. Yanga, G. Lima and Y. Lia
a Department of Materials Science and Engineering, Faculty of Engineering, National University of Singapore, Singapore 117576, Singapore
Received 14 November 2009; revised 10 December 2009; accepted 13 January 2010. Available online 18 January 2010.
Abstract
We have found that better glass former can be obtained in the binary Zr-Cu binary alloys with high oxygen content. However, the best glass former is shifted to different composition as oxygen content changes. Our findings provide an important insight into the mechanism of the oxygen on glass formation which is a useful guideline for designing new BMGs with low grade materials and low processing cost.
Keywords: Glass Formation, Metallic Glass, Alloys, Zr-Cu, Oxygen
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Quantitative determination of free volume in Pd40Ni40P20 bulk metallic glass
Yuanli Xua, b, c, Jixiang Fanga, c, Herbert Gleitera, Horst Hahna, c and Jiangong Lib
a Institute for Nanotechnology, Forschungszentrum Karlsruhe, P. O. Box 3640, 76021 Karlsruhe, Germany
b Institute of Materials Science and Engineering, Lanzhou University, Lanzhou 730000, China
c Joint Research Laboratory of Nanomaterials, Technishce Universität Darmstadt, Petersenstr. 23, 64287 Darmstadt, Germany
Received 10 August 2009; revised 2 December 2009; accepted 13 January 2010. Available online 18 January 2010.
Abstract
The determination of the free volume is a long-time challenging problem in research on metallic glasses. An approach to determine quantitatively free volume of metallic glasses from enthalpy measurements and calibration with the equilibrium free volume was developed and validated for as-cast and annealed Pd40Ni40P20 bulk metallic glasses. The free volume change with annealing time is in good agreement with that calculated theoretically from the free volume annihilation kinetics and that deduced from the density measurement results.
Keywords: Bulk Metallic Glass; Differential Scanning Calorimetry (Dsc); Suction Casting; Annealing; Free Volume
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Wetting phenomena in CuZr-based glassy alloys/W system
Na Liua, b, Haifeng Zhanga, Hong Lia and Zhuangqi Hua
a Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
b Graduate School of the Chinese Academy of Sciences, Beijing 100039, China
Received 31 August 2009; revised 7 January 2010; accepted 9 January 2010. Available online 18 January 2010.
Abstract
The wetting behavior and interfaces of CuZr-based glassy alloys/W system were investigated by the sessile drop method. It was found that Cu50Zr50/W, Cu47.5Zr47.5Al5/W and Cu40Zr44Al8Ag8/W system had the final equilibrium contact angle around 18°, 8°?and 3°?at corresponding experimental temperatures. Base on the scanning electron microscopy observing, no reaction product can be found at the interface of Cu47.5Zr47.5Al5/W and Cu40Zr44Al8Ag8/W, and some granular reaction products appeared along the interface of Cu50Zr50/W. The present work indicates that Cu47.5Zr47.5Al5 and Cu40Zr44Al8Ag8 bulk metallic glasses (BMGs) are appropriate for the fabrication of W reinforced BMGs matrix composite.
Keywords: Wettability; Diffusion; Composite; Metallic glasses
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Glass-Forming Ability and Competitive Crystalline Phases for Lightweight Ti-Be–Based Alloys
Y. Zhang1, W.G. Zhang1, 2, J.P. Lin1, G.J. Hao1, G.L. Chen1 and P.K. Liaw3
(1) State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing, 100083, China
(2) Present address: Chinese Academy of Space Technology, Beijing, 100083, China
(3) Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996-2200, USA
Abstract The glass-forming ability (GFA) for the Ti-Be–based alloys in the Ti-Be-Zr ternary system is systematically studied. It was found that the best GFA obtained at a composition of Ti41Be34Zr25 (at. pct) in the Ti-Be-Zr ternary system, and the bulk-metallic-glass (BMG) rod samples with a diameter of 5 mm were fabricated by Cu-mold casting. The competitive crystalline phases around the composition of the best GFA materials were determined by scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The GFA of the ternary alloys was further improved by an addition of 4 at. pct vanadium (V). The largest supercooled liquid region, ΔT x (ΔT x = T x − T g , T g is the glass-transition temperature, and T x the crystallization temperature), in the ternary alloy system reaches about 110 K (110 °C) for the Ti35Be32Zr33 alloy.
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Enhancement of plastic deformability in Fe–Ni–Nb–B bulk glassy alloys by controlling the Ni-to-Fe concentration ratio
J. M. Park,1,3 G. Wang,1 R. Li,1 N. Mattern,1 J. Eckert,1,2 and D. H. Kim3
1Institute for Complex Materials, IFW Dresden, P.O. Box 27 01 16, D-01171 Dresden, Germany
2Institute of Materials Science, TU Dresden, D-01062 Dresden, Germany
3Department of Metallurgical Engineering, Center for Non-Crystalline Materials, Yonsei University, 134 Shinchon-dong Seodaemun-gu, Seoul 120-749, Republic of Korea
The influence of partial replacement of Fe by Ni in (Fe1−xNix)71Nb6B23 (0 x0.5) bulk glassy alloys on the enhancement of the plasticity has been investigated. The increase of the Ni-to-Fe concentration ratio effectively improves the compressive plasticity. The (Fe0.5Ni0.5)71Nb6B23 alloy exhibits an enhanced plastic strain of ~4.2%, together with high strength and distinct strain hardeninglike characteristics, when compared with the Ni-free Fe71Nb6B23 glass. The improved mechanical properties are ascribed to the control of the intrinsic elastic properties, followed by favorably tuning the interatomic interaction. ©2010 American Institute of Physics
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Effect of strain rate on the yielding mechanism of amorphous metal foam
Joseph P. Schramm,1 Marios D. Demetriou,1 William L. Johnson,1 Benny Poon,2 Guruswami Ravichandran,2 and Daniel Rittel3
1Keck Engineering Laboratories, California Institute of Technology, Pasadena, California 91125, USA
2Graduate Aerospace Laboratories, California Institute of Technology, Pasadena, Pasadena, California 91125, USA
3Faculty of Mechanical Engineering, Technion, 32000 Haifa, Israel
Stochastic amorphous Pd43Ni10Cu27P20 foams were tested in quasistatic and dynamic loading. The strength/porosity relations show distinct slopes for the two loading conditions, suggesting a strain-rate-induced change in the foam yielding mechanism. The strength/porosity correlation of the dynamic test data along with microscopy assessments support that dynamic foam yielding is dominated by plasticity rather than elastic buckling, the mechanism previously identified to control quasistatic yielding. The strain-rate-induced shift in the foam yielding mechanism is attributed to the rate of loading approaching the rate of sound wave propagation across intracellular membranes, thereby suppressing elastic buckling and promoting plastic yielding. ©2010 American Institute of Physics
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