Partially vitrified Zr60Cu10Al15Ni15 bulk metallic glass has been synthesized using water cooled copper mold drop casting technique. Kinetically favorable microstructures having different morphologies are observed throughout the volume of the bulk metallic glass sample. X-ray diffraction studies indicate formation of hard intermetallic compounds such as Zr3Al2 and Zr2Ni in certain regions along with amorphous structures. Microindentation studies carried out in different regions of the sample reveal microstructure dependent deformation behavior. Highest hardness is observed in the fully crystallized regions compared to pure glassy regions in the same sample. Further nanoindentation in the same sample is used to understand dynamic mechanical properties of microstructures in different regions. The pile-up morphologies around the indent and differences in load-displacement curves provide vital information on deformation behavior of sample in different microstructure sensitive regions. © 2014 Elsevier Ltd.

Budaraju Srinivasa Murty

Department of Metallurgical and Materials Engineering

Aluminum

Deformation

Glass

INTERMETALLICS

Mechanical properties

microstructure

Morphology

Nickel

Piles

X ray diffraction

Zirconium

AMORPHOUS STRUCTURES

Bulk metallic glass

Deformation behavior

DYNAMIC MECHANICAL PROPERTY

LOAD-DISPLACEMENT CURVE

Micro indentation

MICRO- AND NANO-INDENTATION

X-ray diffraction studies

Metallic glass

Fulltext

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Materials and Design

The energetics behind transformation of liquid structure into subsequent intermediate phases during solidification is expected to play a decisive role in glass/crystal formation. A great deal of experimental and simulation work on supercooled liquids has indicated that, there exists a close link between the liquid structure and icosahedral clusters, especially for bulk metallic glass forming liquids. Pertinently, icosahedral clusters are also found to be energetically favorable to form upon devitrification of Zr60Cu10Al15Ni15 glassy alloy. Such evolution of icosahedral clusters upon devitrification in this alloy invariably proves their manifestation at the intermediate stage during transition of supercooled liquid into glass. Hence understanding the energetics behind restructuring of these clusters into glass or crystal during solidification, aids in microstructure optimization of glass/crystal composites for structural and functional applications. In this paper, it has been attempted to investigate the energetics behind the evolution of Zr–Ni and Zr–Al binary intermetallic phases during crystallization of Zr60Cu10Al15Ni15 glassy alloy. Ascalaph Designer Molecular Modeling Suite is used to generate different models of clusters to understand the formation of Zr–Ni and Zr–Al phases. We propose solidification mechanism in this alloy via two steps, namely, formation of intermediate Zr–Cu icosahedral clusters which is structurally restricted process and precipitation of crystalline phases as thermodynamically favorable process. © 2015, The Indian Institute of Metals - IIM.

Transactions of the Indian Institute of Metals

Icosahedral Cluster Energetics in Zr60Cu10Al15Ni15 Bulk Metallic Glass and Their Role on Solidification Behavior

In the present investigation, deformation behavior of melt spun glassy ribbon of Cu 60Zr 20Ti 20 has been studied using microhardness test. Further, the glassy ribbon was annealed at supercooled liquid region (ΔT x), offset of first crystallization (T x1) and offset of second crystallization temperature (T x2). X-ray diffraction and transmission electron microscopy has been used to understand the crystallization behavior of the glass and to correlate its microstructural evolution with the mechanical properties. The glassy alloy initially undergoes phase separation during annealing which transforms into a totally crystalline structure after annealing at T x2 temperature. It has been observed that at any particular load, the hardness of the alloy increases with the progress of phase separation and partial crystallization. After complete crystallization the hardness drops off. This leaves behind the scope of microstructural engineering of metallic glasses and composites for best enhancement of properties. Further the role of phase separation on the indentation behavior of this glassy alloy has been explored. The role of relaxation and crystallization on hardness and deformation behavior of glassy ribbon alloy is examined by observing the indentations under scanning electron microscopy. Results indicate that the composite structure formed during annealing at T x1 has superior hardness in comparison to other microstructures. © 2012 Elsevier B.V.

Materials Science and Engineering A

Micro indentation study on Cu 60Zr 20Ti 20 metallic glass

Dry sliding wear of as cast and different annealed states of Cu60Zr30Ti10 bulk metallic glass was studied using pin-on-disc measurement technique. The relaxed metallic glass showed high hardness and excellent wear resistance. An inverse relation between the hardness and wear rate was observed for the as cast and annealed metallic glass. Coefficient of friction measured for all the above samples was found in a narrow range of 0.3-0.4 being less for as cast sample. © 2007.

Tribological behaviour of Cu60Zr30Ti10 bulk metallic glass

Nanoindentation studies on rapidly solidified Zr 80Pt 20 and Zr 75Pd 25 binary alloys with nanocrystalline, nanoquasicrystalline, and amorphous microstructures are reported. The results indicate that the hardness and elastic modulus are the highest for a mixture of amorphous and nanoquasicrystalline state among the various microstructures studied. Nanoquasicrystalline phase has high hardness and elastic modulus in comparison to amorphous and nanocrystalline phases. The hardness to modulus ratio is close to 0.1 in both the alloys, irrespective of the phase/phase mixture studied indicating that the bonding in these alloys is of covalent nature. In Zr 80Pt 20, all the phases/phase mixtures have higher hardness and modulus in comparison to similar microstructures in Zr 75Pd 25 due to higher bond energies caused by more negative heat of mixing in the former case. Copyright © 2007 American Scientific Publishers All rights reserved.

Journal of Nanoscience and Nanotechnology

Nanoindentation studies on amorphous, nanoquasicrystalline and nanocrystalline Zr 80Pt 20 and Zr 75Pd 25 alloys

Journal of Alloys and Compounds

Kinetic competition during glass formation

Materials & Design (1980-2015)

Enhanced ductility in a Zr65Cu15Al10Ni10 bulk metallic glass by nanocrystallization during compression

Micro and nano indentation studies on Zr60Cu10Al15Ni15 bulk metallic glass

Journal	Data powered by TypesetMaterials and Design
Publisher	Data powered by TypesetElsevier Ltd
ISSN	02613069
Open Access	Yes