Atomic-level structure and structure–property relationship in metallic glasses

REVIEW ARTICLE: Glassy metals

The minimum solute concentration in a binary alloy system necessary to obtain a stable amorphous phase by rapid quenching, C B min , collected from the published reports on glass formation of 66 systems, was found to be inversely correlated with the atomic volume mismatch, | (v b −v A v A | , where v A is the atomic volume of the matrix and v B is the atomic volume of the solute. The atomic scale elasticity theory was developed to calculate the atomic level stresses in solid solution, which led to the stress criteria for the topological instability of solid solution. It was found that C B min is closely correlated with the critical solute concentration for the topological instability of solid solution. This result indicates that the atomic size ratio between the constituent elements is the most important factor in the determination of value of C B min , and the amorphous alloys are stabilized partly because the solid solutions of the corresponding compositions are topologically unstable.

Atomic size effect on the formability of metallic glasses

Nanocrystalline materials an approach to a novel solid structure with gas-like disorder?

Introduction Motivation Advanced Materials Rapid Solidification Processing Mechanical Alloying Outline of the Book Metallic Glasses Distinction between Crystals and Glasses Differences between Amorphous Alloys and Metallic Glasses The Concepts of Glass Formation Thermodynamics and Kinetics of Glass Formation Methods to Synthesize Metallic Glasses Bulk Metallic Glasses Potential Resources of Literature on Metallic Glasses Glass-Forming Ability of Alloys Critical Cooling Rate Reduced Glass Transition Temperature Deep Eutectics Topological Models Bulk Metallic Glasses Inoue Criteria Exceptions to the Above Criteria New Criteria Transformation Temperatures of Glasses Thermodynamic Modeling Structural and Topological Parameters Physical Properties Computational Approaches Miscellaneous Criteria Criteria for Glass Formation by Non-Solidification Methods Synthesis of Bulk Metallic Glasses Principles of Rapid Solidification Processing General Techniques to Achieve High Rates of Solidification Melt Spinning Bulk Metallic Glasses Bulk Metallic Glass Casting Methods Bulk Metallic Glass Composites Mechanical Alloying Bulk Metallic Glass Foams Crystallization Behavior Methodology Crystallization Modes in Melt-Spun Ribbons Differences in the Crystallization Behavior between Melt-Spun Ribbons and Bulk Metallic Glasses Thermal Stability of Metallic Glasses Crystallization Temperatures and Their Compositional Dependence Annealing of Bulk Metallic Glasses Effect of Environment Effect of Pressure during Annealing Physical Properties Density Thermal Expansion Diffusion Electrical Resistivity Specific Heat Viscosity Corrosion Behavior Terminology and Methodology Copper-Based Bulk Metallic Glasses Iron-Based Bulk Metallic Glasses Magnesium-Based Bulk Glassy Alloys Nickel-Based Bulk Metallic Glasses Titanium-Based Bulk Metallic Glasses Zirconium-Based Bulk Metallic Glasses Other Bulk Metallic Glassy Alloys Mechanical Behavior Deformation Behavior Deformation Maps Temperature Rise at Shear Bands Strength Ductility Fatigue Yield Behavior BMG Composites Magnetic Properties Soft Magnetic Materials Nanocrystalline Alloys Hard Magnetic Materials Applications Special Characteristics of Bulk Metallic Glasses Structural Applications Chemical Applications Magnetic Applications Miscellaneous Applications Epilogue Size and Shape Mechanical Properties Magnetic Properties Fundamental Properties Index References appear at the end of each chapter.

Bulk Metallic Glasses

The structure of metallic glasses containing boron (FeB, CoB, and NiB) is investigated by X-ray diffraction. Using the common Fourier analysis, the atomic radial distribution function is evaluated from which interatomic distance and coordination number are obtained. The present results indicate that the atomic distribution of metallic glasses with boron content less than 20 at%, differs from that observed previously for a number of metallic glasses such as Fe83P17.



Die Struktur metallischer Glaser, die Bor (FeB, CoB und NiB) enthalten, wird rontgenographisch untersucht. Die atomare Intensitatsverteilungsfunktion wird mit Hilfe einer Fourieranalyse bestimmt, und Atomabstande und Koordinationszahlen werden berechnet. Die Resultate zeigen, das die Atomverteilung in metallischen Glasern mit weniger als 20At% Bor nicht mit der bisher in Glasern des Fe83P17-Typs gefundenen Verteilung ubereinstimmt.

A structural study of metallic glasses containing boron (FeB, CoB, and NiB)

A detailed structural analysis is carried out for series of ZrCu and NbNi alloy glasses by X-ray diffraction. The interatomic distances of ZrZr, ZrCu, NbNb, and NbNi pairs are found to be significantly less than the correspoding Goldschmidts' radii and to decrease with increasing Cu and Ni contents. The composition effect on the structure and characteristic structural features of these alloy glasses are also described with a comparison to those of metal-metalloid glasses.



Eine eingehende rontgenographische Strukturanalyse wird fur Legierungsglaser der ZrCu- und NbNi-Reihe durchgefuhrt. Es wird gefunden, das die iteratomaren Abstande der ZrZr-,ZrCu-,NbNb- und Nb-Ni-Paare betrachtlich kleiner als die entsprechenden Goldschmidt-Radien sind und mit zunehmendem Cu- und Ni-Gehalt abnehmen. Der Einflus der Zusammensetzung auf die Struktur und die charakteristischen Struktureigenschaften dieser Legierungsglaser werden beschrieben und mit denen der metallisch-metalloidischen Glaser verglichen.

Structure of glassy ZrCu and NbNi alloys

The positron lifetime of a glassy Pd0.775Cu0.06Si0.165 alloy decreases only slightly on crystallization. This suggests that the glassy alloy contains negligible fractional concentration (< 10−5) of vacancy-like defects, and the crystallite model may be excluded as a possible structure of metallic glasses; however, a modified crystallite model is possible. It is observed that an amorphous–crystalline boundary constitutes a very small fraction of positron trapping sites, and is concluded that the amorphous–crystalline interphase exhibits a smooth transition structure. This contrasts to a grain boundary which consists of atomic layers of low density regions.



Die Positronenlebensdauer einer glasartigen Pd0,775Cu0,06Si0,165-Legierung geht bei der Kristallisierung nur leicht zuruck. Somit enthalt die glasartige Legierung vermutlich geringfugige Anteile (< 10−5) leerstellenartiger Fehler und das Kristallitmodell scheidet als mogliche Struktur metallischer Glaser aus, jedoch ist ein abgewandeltes Kristallitmodell moglich. Die amorph–kristalline Grenzphase ergibt, wie beobachtet, einen sehr kleinen Anteil von Positroneneinfangstellen und weist folglich eine glatte Ubergangsstruktur auf. Dies unterscheidet sie von einer Korngrenze, welche aus Atomlagen geringer Dichte besteht.

Positron lifetime study on the structure of a metallic glass and interphase boundaries

Switching phenomena in chalcogenide glasses have been analysed as a thermoelectric effect. Computer calculations relating current, voltage, temperature, and time have been made. The results show a very fast switching but a slower cut-off. The temperature of the diode changes abruptly on switching. The calculated holding voltage in the conducting state is found to be nearly constant and independent of the ambient temperature. The main features of the results agree with the experimental data.

H. S. Chen

Papers

A structural study of metallic glasses containing boron (FeB, CoB, and NiB)

Structure of glassy ZrCu and NbNi alloys

Positron lifetime study on the structure of a metallic glass and interphase boundaries

On the theory of switching phenomena in semiconducting glasses

Positron lifetime study on the structure of an electron irradiated metallic glass