https://www.tcd.ie/Physics/people/Graham.Cross/SF%20Poster%202011/Inoue-ActaMater00-Stabilization%20of%20metallic%20supercooled%20liquid%20and%20bulk%20amorphous%20alloys.pdf

Stabilization of metallic supercooled liquid and bulk amorphous alloys

Amorphous alloys were first developed over 40 years ago and found applications as magnetic core or reinforcement added to other materials. The scope of applications is limited due to the small thickness in the region of only tens of microns. The research effort in the past two decades, mainly pioneered by a Japanese- and a US-group of scientists, has substantially relaxed this size constrain. Some bulk metallic glasses can have tensile strength up to 3000 MPa with good corrosion resistance, reasonable toughness, low internal friction and good processability. Bulk metallic glasses are now being used in consumer electronic industries, sporting goods industries, etc. In this paper, the authors reviewed the recent development of new alloy systems of bulk metallic glasses. The properties and processing technologies relevant to the industrial applications of these alloys are also discussed here. The behaviors of bulk metallic glasses under extreme conditions such as high pressure and low temperature are especially addressed in this review. In order that the scope of applications can be broadened, the understanding of the glass-forming criteria is important for the design of new alloy systems and also the processing techniques.

https://www.tcd.ie/Physics/people/Graham.Cross/SF%20Poster%202011/Shek-MaterSciEng04-Bulk%20Metallic%20Glasses.pdf

Bulk metallic glasses

Bulk metallic glasses (BMGs) have been classified according to the atomic size difference, heat of mixing (� H mix ) and period of the constituent elements in the periodic table. The BMGs discovered to date are classified into seven groups on the basis of a previous result by Inoue. The seven groups are as follows: (G-I) ETM/Ln-LTM/BM-Al/Ga, (G-II) ETM/Ln-LTM/BM-Metalloid, (G-III) Al/Ga-LTM/BMMetalloid, (G-IV) IIA-ETM/Ln-LTM/BM, (G-V) LTM/BM-Metalloid, (G-VI) ETM/Ln-LTM/BM and (G-VII) IIA-LTM/BM, where ETM, Ln, LTM, BM and IIA refer to early transition, lanthanide, late transition, group IIIB–IVB and group IIA-group metals, respectively. The main alloying element of ternary G-I, G-V and G-VII, ternary G-II and G-IV, and ternary G-VI BMGs is the largest, intermediate and smallest atomic radius compared to the other alloying elements, respectively. The main alloying element of ternary BMGs belonging to G-I, G-V, G-VI and G

Classification of Bulk Metallic Glasses by Atomic Size Difference, Heat of Mixing and Period of Constituent Elements and Its Application to Characterization of the Main Alloying Element

The following article is based on the MRS Medal talk presented by William L. Johnson at the 1998 MRS Fall Meeting on December 2, 1998. The MRS Medal is awarded for a specific outstanding recent discovery or advancement that has a major impact on the progress of a materials-related field. Johnson received the honor for his development of bulk metallic glass-forming alloys, the fundamental understanding of the thermodynamics and kinetics that control glass formation and crystallization of glass-forming liquids, and the application of these materials in engineering.The development of bulk glass-forming metallic alloys has led to interesting advances in the science of liquid metals. This article begins with brief remarks about the history and background of the field, then follows with a discussion of multicomponent glass-forming alloys and deep eutectics, the chemical constitution of these new alloys, and how they differ from metallic glasses of a decade ago or earlier. Recent studies of deeply undercooled liquid alloys and the insights made possible by their exceptional stability with respect to crystallization will then be discussed. Advances in this area will be illustrated by several examples. The article then describes some of the physical and specific mechanical properties of bulk metallic glasses (BMGs), and concludes with some interesting potential applications.The first liquid-metal alloy vitrified by cooling from the molten state to the glass transition was Au-Si, as reported by Duwez at Caltech in 1960. Duwez made this discovery as a result of developing rapid quenching techniques for chilling metallic liquids at very high rates of 105–106 K/s.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0883769400053252

Bulk Glass-Forming Metallic Alloys: Science and Technology

The factors of the atomic size difference Delta and the enthalpy of mixing ΔH mιx of the multi-component alloys were summarized from the literatures. The formation zones of solid-solution phases, intermediate phases, and bulk metallic glasses were determined and the validity was verified by experimental results. For forming the solid solution, the alloys should have high entropy of mixing, lower Delta, and not too negative and positive enthalpy of mixing.

Solid‐Solution Phase Formation Rules for Multi‐component Alloys

Recently, the present authors found a highly processable metallic glass with a low critical cooling rate of 10 K s −1 or less. This glassy alloy showed several interesting features such as high thermal stability in the supercooled liquid region, and a strong dependence of the crystallization temperature on the heating rate as well as on the environment. In order to process these materials in the supercooled liquid region, time-temperature-transformation (TTT) diagrams are very useful. We report the calculation of the TTT diagram as well as its comparison with experimental results. From the constructed TTT diagram, it is concluded that these excellent glass-forming alloys which require very low critical cooling rates also tend to have a strong dependence of the crystallization temperature on the heating rate. It is also proposed that heterogeneous nucleation is an important factor in the crystallization of these alloys.

Time-temperature-transformation diagram of a highly processable metallic glass

A diamond-containing metal-matrix composite material is formed by dispersing pieces of diamond throughout a melt of a bulk-solidifying amorphous metal and solidifying the mixture. The mixture may then be remelted and resolidified at a rate sufficiently high that the metal matrix retains an amorphous structure upon cooling. The metal preferably has a composition of about that of a eutectic composition, and most preferably has a composition, in atomic percent, of from about 45 to about 67 percent total of zirconium plus titanium, from about 10 to about 35 percent beryllium, and from about 10 to about 98 percent total of copper plus nickel. The diamond is preferably low-grade or artificial diamond.

Amorphous metal/diamond composite material

Jewelry and methods of making jewelry containing a precious metal-base alloy component in bulk-solidified amorphous phase are provided.

Jewelry made of precious a morphous metal and method of making such articles

A method of investment casting bulk-solidifying amorphous alloys, and the formation of articles of bulk-solidifying amorphous alloys made by such methods are provided.

Investment casting of bulk-solidifying amorphous alloys

A metallic melt of composition Al52.6Cu13.4Ge28Si6 was processed for 2 h in a centrifuge at a temperature of 530 °C and inertial acceleration of 60 000 g (g=gravitational acceleration), and then slowly cooled to room temperature during continuous centrifugation. Primary phases forming in the melt during cooling were sequentially separated from the remaining liquid, changing the composition of the liquid, until it solidified in a ternary eutectic microstructure of composition Al64Cu3Ge33. Presenting scanning electron microscope images, we demonstrate that this method of high-temperature centrifugation is a efficient tool to isolate and identify multiphase eutectic compositions and the sequence of crystallization in multicomponent alloys. The latter is particularly useful for the discovery of new bulk metallic glasses.

Atakan Peker

Papers

Time-temperature-transformation diagram of a highly processable metallic glass

Amorphous metal/diamond composite material

Jewelry made of precious a morphous metal and method of making such articles

Investment casting of bulk-solidifying amorphous alloys

High-temperature centrifugation: a tool for finding eutectic compositions in multicomponent alloys