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

https://www.tcd.ie/Physics/people/Graham.Cross/SF%20Poster%202011/Schuh-ActaMater07-Mechanical%20behaviour%20of%20amorphous%20alloys.pdf

Mechanical behavior of amorphous alloys

Shock compression of solids

The demand for light-weighting in transport and consumer electronics has seen rapid growth in the commercial usage of magnesium (Mg). The major use of Mg is now in cast Mg products, as opposed to the use of Mg as an alloying element in other alloy systems and there is an emerging market of wrought Mg products and biomedical Mg components – such that the past two decades have seen a significant number of new Mg-alloys reported. None-the-less, the corrosion of Mg alloys continues to be a challenge facing engineers seeking weight reductions by deployment of Mg. Herein, authors review the influence of alloying on the corrosion of Mg-alloys, with particular emphasis on the underlying electrochemical kinetics that dictate the ultimate corrosion rate. Such a review focusing on the chemistry–corrosion link, both in depth and in a holistic approach, is lacking. As such the authors do not describe aspects such as high-temperature oxidation or cracking, but focus on delivering the state-of-the-art with regar...

Corrosion of magnesium alloys: the role of alloying

The O−Zr (Oxygen-Zirconium) system

Amorphous Fe-17 at %B alloy prepared by a splat-quenching technique was annealed at temperatures ranging from 250 to 500° C for different periods. A time-temperature transformation diagram has been constructed from X-ray diffraction examination of annealed samples. On annealing the alloy at a pressure of 50 kbar, an appreciable retardation of crystallization was observed. The crystalline phase precipitated first from the amorphous matrix at 1 bar. This was α-Fe containing a small amount of boron, but at 50 kbar this was a mixture of α-Fe(B) and intermetallic phase Fe3B. Under the increased pressure of 100 kbar the mode of the crystallization was further changed and Fe3B became the first precipitating phase. Preferential formation of Fe3B under pressure can be explained assuming a modified dense-random packing model for the amorphous structure.

Effect of high pressure on the crystallization of an amorphous Fe83 B17 alloy

Amorphous Ti-20 at% Si alloy, prepared by rapid quenching from the molten state, was annealed while being subjected to a pressure of 10GPa. X-ray diffraction investigations on the alloy specimens quenched to ambient conditions have shown that pressure greatly alters the crystallization characteristics and a body-centered cubic solid solution having the same composition as that of the parent amorphous matrix forms preferentially at temperatures in the range from 400 to 550° C. The lattice constant of this supersaturated solid solution suggests that silicon atoms are dissolved substitutionally in the titanium lattice. It is not until the temperature is raised to above 550° C that the amorphous matrix decomposes into a bcc solid solution containing less amount of silicon and a silicon-rich phase. Discussion is given on the mode of crystallization on the basis of the present results and those of previous studies and it has been shown that the crystallization of amorphous alloys can be classified into three types depending on pressure and temperature.

Crystallization characteristics of an amorphous Ti80Si20 alloy at high pressures

The crystal structures of the ordered phases in the Au-Zn alloy system have been studied in detail by means of X-ray and electron diffraction on single crystal samples, and the order-disorder and other kinds of phase transitions involved in the present system have also been studied by the measurement of specific heat. The previously proposed structures of Au 3+ Zn, Au 3 Zn[H], Au 3 Zn[R] have substantially been confirmed and that of Au 5 Zn 3 only partly. Moreover, the details in these structures have been revealed: in Au 3+ Zn some type of the strong lattice modulation is present, and in Au 3 Zn[R] the two types of structure. Au 3 Zn[R 1 ] and Au 3 Zn[R 2 ], certainly exist. The transition behavior of the alloys with changing temperature has been investigated on samples of various compositions and the thermodynamic data obtained are presented. The phase diagram of the Au-rich side of the present system is reasonably corrected by the present experiment. The orientation distribution of the ordered crystals...

Study on the Ordered Phases with Long Period in the Gold-Zinc Alloy System I. Survey of Crystal Structures and Calorimetric Measurement

Crystal structures of palladium-manganese alloys with compositions in the neighborhood of 25at.%Mn have been studied, and it has been confirmed that the alloys with manganese less than about 24at.% have the disordered F.C.C. lattice and those with the manganese contents ranging from about 24 to 30at.% the one-dimensional long period ordered structure with M =2. Refinement of the structure analysis of the long period ordered alloy Pd 3 Mn by X-ray diffraction has been made using single crystals, and periodic atom displacements of the heavy and light atoms have been found to occur with displacement directions similar to those in Cu 3 Pd(α''), the magnitude of displacements being as small as 0.01A for both the kinds of atom. These atom displacements are discussed in relation to the electron-atom ratio of the alloy. Neutron diffraction powder patterns have been observed, in order to see whether the nuclei in Pd 3 Mn are displaced together with the electron clouds belonging to them or not, but no definite conc...

Lattice Modulation in the Long Period Ordered Alloys Studied by X-Ray Diffraction. II. CuAuII

Amorphous Nb-19 at% Si alloy, prepared by rapid quenching from the molten state, was annealed while being subjected to a pressure of 10 GPA. X-ray diffraction investigations on the alloy specimens quenched to ambient conditions have shown that pressure greatly alters the crystallization characteristics and the cubic A15 (Nb3Si)-phase forms in preference to the tetragonal Nb3Si-phase at temperatures in the range from 710° C to 800° C. Up to 680° C, the component atoms do not show any tendency towards ordering upon crystallization and the body-centred tetragonal solid solution forms; while, at 830° C, niobium atoms diffuse to form the body-centred cubic Nb precipitates. Superconducting properties have been measured for the single-phase A15 structure with the lattice parametera=0.5155 nm with the results that the transition temperature,TC, is 3.4 K and the temperature coefficient of the upper critical field,HC2, is 1.2 MA m−1 K−1 (15 kOe K−1).

Hiroshi Iwasaki

Papers

Effect of high pressure on the crystallization of an amorphous Fe83 B17 alloy

Crystallization characteristics of an amorphous Ti80Si20 alloy at high pressures

Study on the Ordered Phases with Long Period in the Gold-Zinc Alloy System I. Survey of Crystal Structures and Calorimetric Measurement

Lattice Modulation in the Long Period Ordered Alloys Studied by X-Ray Diffraction. II. CuAuII

Crystallization characteristics of an amorphous Nb81Si19 alloy under high pressure and formation of the A15 phase