Glass-forming ability of alloys

Inoue, Akihisa; Zhang, Tao; Masumoto, T.

doi:10.1016/0022-3093(93)90003-g

Cited by 663 publications

(324 citation statements)

References 10 publications

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“…In both cases, a strong dependence of ⌬T and d c on the composition variations can be observed. However, no obvious correlation between ⌬T and d c , as previously reported to be positive 22,23 or negative, 20,24 was observed.…”

mentioning

confidence: 49%

Gold based bulk metallic glass

Schroers

Lohwongwatana

Johnson

et al. 2005

Applied Physics Letters

231

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Gold-based bulk metallic glass alloys based on Au-Cu-Si are introduced. The alloys exhibit a gold content comparable to 18-karat gold. They show very low liquidus temperature, large supercooled liquid region, and good processibility. The maximum casting thickness exceeds 5 mm in the best glassformer. Au 49 Ag 5.5 Pd 2.3 Cu 26.9 Si 16.3 has a liquidus temperature of 644 K, a glass transition temperature of 401 K, and a supercooled liquid region of 58 K. The Vickers hardness of the alloys in this system is ϳ350 Hv, twice that of conventional 18-karat crystalline gold alloys. This combination of properties makes the alloys attractive for many applications including electronic, medical, dental, surface coating, and jewelry. Gold became known to mankind thousands years ago, and has been of inestimable value to civilization ever since. It is the noblest of the noble metals, and has a good combination of high thermal conductivity, high electrical conductivity, and high corrosion resistance. These properties have resulted in extensive use of gold and its alloys in electronic, aerospace, astronomy, medical, and industrial applications. For instance, gold can be found in many of today's sophisticated electronic devices. However, gold has always been most valued as a jewelry material. Gold alloys are easy to fashion, are nonallergenic, have a bright pleasing color, and remain tarnish free indefinitely. Pure gold and higher karat gold alloys, however, are rather soft and therefore vulnerable to wear and scratching. This results in diminished aesthetic appearance, and is a drawback of conventional crystalline gold alloys.In the last two decades, several alloys based on Pd, 1-3 La, 4 Zr, 5,6 Fe, 7-9 and Pt 10 were found to form bulk amorphous phases. Fully amorphous samples are obtained when the alloys are cast into copper molds of diameter up to centimeters which indicates critical cooling rates for glass formation of 100 K / s or less. These bulk metallic glasses ͑BMGs͒ exhibit properties such as high strength, large elastic strain limit, high hardness, and, in some cases, substantial ductility. 11 The compositions of these BMGs are typically close to a deep eutectic composition. Consequently, their melting temperatures are much lower than estimated from interpolation of the alloy constituents' melting temperatures. The resulting low liquidus temperature is an attractive property for casting alloys. The extraordinary stability of BMG forming alloys against crystallization also results in a large supercooled liquid region, ⌬T, ͑⌬T = T x -T g , T x : crystallization temperature, T g : glass transition temperature͒, the temperature region in which the amorphous phase first relaxes into a highly viscous liquid before eventually crystallizing.In this temperature region, BMG's are amenable to superplastic processing using netshape processing methods similar to those employed for thermoplastics. 12 The binary gold silicon eutectic composition was the first alloy found to exhibit metallic glass formation by Duwez and co-workers in ...

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mentioning

confidence: 49%

Gold based bulk metallic glass

Schroers

Lohwongwatana

Johnson

et al. 2005

Applied Physics Letters

231

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“…% ͒ MGs do not exhibit such primary precipitation. 8 Furthermore, Zr-Cu binary MGs exhibit a glass transition event, whereas Zr-Ni binary MGs do not, 14 which might be due to their different atomic structures. 8 Thus, studies of atomic structure in such simple MGs are strongly demanded, which will promote our understanding to multicomponent bulk metallic glasses.…”

Section: Introductionmentioning

confidence: 99%

Atomic structure in Zr70Ni30 metallic glass

Yang

Yin

Wang

et al. 2007

Journal of Applied Physics

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Atomic structure of Zr 70 Ni 30 metallic glass ͑MG͒ was investigated by reverse Monte Carlo simulation combining with x-ray diffraction and Ni and Zr K-edge extended x-ray absorption of fine structure measurements. Distributions of coordination number ͑CN͒ and Voronoi clusters were analyzed by Voronoi tessellation method. The average CN of atoms was obtained to be 11.4 together with the average CN of Zr and Ni atoms of about 11.8 and 10.6, respectively. It is found that Z11 Kasper polyhedron and distorted icosahedra are mainly favored structural units in INTRODUCTIONAtomic structure of metallic glasses ͑MGs͒ has been studied experimentally and theoretically 1-4 because their extraordinary mechanical and magnetic properties strongly depend on their atomic structures. Gaskell proposed that atomic structure of MG is similar with that of corresponding crystalline phases. 5 Stability of MG is linked with its atomic structure, 6,7 which correlates with atomic structure of the corresponding crystalline phase by annealing. 8,9 For example, icosahedral clusters are found to be dominant atomic structure in Zr 70 Cu 29 Pd 1 MG, 10,11 which leads to primary phase transition by forming icosahedral quasicrystal 12,13 after annealing, while Zr 70 Ni 30−x Pd x ͑x Ͻ 10 at. % ͒ MGs do not exhibit such primary precipitation. 8 Furthermore, Zr-Cu binary MGs exhibit a glass transition event, whereas Zr-Ni binary MGs do not, 14 which might be due to their different atomic structures. 8 Thus, studies of atomic structure in such simple MGs are strongly demanded, which will promote our understanding to multicomponent bulk metallic glasses. However, structure of Zr-Ni MGs is still not completely understood [15][16][17][18] in spite of its wide amorphous-forming compositional range. 19 In the present work, we report the atomic structure of a Zr 70 Ni 30 MG by reverse Monte Carlo ͑RMC͒ simulation combining with x-ray diffraction ͑XRD͒ and extended x-ray absorption of fine structure ͑EXAFS͒ as well as Voronoi tessellation method. EXPERIMENTZr 70 Ni 30 ingot was prepared by arc melting high-purity metals ͑99.8% Zr and 99.9% Ni͒. Amorphous ribbons with a cross section of 0.03ϫ 2 mm 2 were obtained from these alloys by single-roller melt spinning at a wheel surface velocity of 30 m / s in purified Ar atmosphere. The oxygen content of the as-prepared ribbon samples was analyzed to be less than 800 mass ppm by inductively coupled plasma spectroscopy. The influence of oxygen on the transformation behavior can thus be disregarded. 20,21 Room-temperature high resolution XRD measurements were carried out for as-prepared Zr 70 Ni 30 sample with high energy x-ray ͑100 keV͒ at beamline BW5, Hasylab in Germany. Diffraction patterns were recorded by a Mar2300 image plate. Beamstop was located away from the center to record data with larger Q ͑wave vector transfer͒ range, resulting in high resolution in real-space reduced pair distribution function G͑r͒. XRD patterns were integrated to Q-space data file after subtracting its background by the program FIT...

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“…The atomic size ratios of the constitutional elements are 1.28 for Zr/Cu, 1.25 for Hf/Cu, 1.10 for Zr/Ti, 1.09 for Hf/Ti and 1.14 for Ti/Cu, which indicates a small size mismatch in the Zr -Ti, Hf -Ti and Ti -Cu pairs. Heats of mixing have been estimated to be 2 23 kJ/mol for Cu -Zr, 2 17 kJ/mol for Cu -Hf, 0 kJ/mol for Zr -Ti and Hf -Ti and 2 9 kJ/mol for Cu -Ti [3], which are comparatively smaller than those in the typical alloys with high GFA [4,5]. It is noted that Zr -Ti and Zr -Hf pairs have no chemical affinity.…”

Section: Introductionmentioning

confidence: 99%

Nano structure of rapidly quenched Cu–(Zr or Hf) – Ti alloys and their devitrification process

Saida

Osuna

Ohnuma

et al. 2003

Science and Technology of Advanced Materials

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The structure and primary devitrification process of the melt-spun Cu 60 (Zr or Hf) 30 Ti 10 alloys were investigated. It was confirmed that the compositional segregation in the diameter range of 5 -10 nm exists in the as-quenched state. The nanocrystalline particles with cubic structure are observed in the glassy matrix in the high-resolution transmission electron microscopy images, of which size is corresponding to the scale of compositional segregation. Small-angle X-ray scattering measurement also indicates the development of nanoscale inhomogeneity with the same size as that of nanocrystalline particles. The nanocrystalline region has high Cu content. In contrast, Zr or Hf and Ti elements are enriched in the glassy region. These results are recognized as the formation of novel structure consisting of the glassy and nanocrystalline phases. It is suggested that the precipitation of bcc CuZr phase as a primary crystallization phase proceeds in the glassy phase remaining the nanocrystalline phase in the Cu-Zr -Ti alloy. Meanwhile, the glassy and nanocrystalline phases are transformed to an orthorhombic Cu 8 Hf 3 phase at the initial crystallization stage in the Cu -Hf -Ti alloy. These differences of crystallization process are consistent with the results of thermodynamic and kinetic analyses of the transformation mode. q

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Glass-forming ability of alloys

Cited by 663 publications

References 10 publications

Gold based bulk metallic glass

Gold based bulk metallic glass

Atomic structure in Zr70Ni30 metallic glass

Nano structure of rapidly quenched Cu–(Zr or Hf) – Ti alloys and their devitrification process

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