metallic glass

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SYNTHESIS AND CHARACTERIZATION OF Ce65al25co10
METALLIC GLASS

• Presentation
• Session 2015-16
• UNDER THE SUPERVISION OF
  BY
• Dr. R. S. TIWARI
  
  MOHD ALAM
• Professor and Head,
  
  M.Sc.(final)
• Department Of Physics,
  
  
  Enrolment No.-331085
• Banaras Hindu University
  
  
  Roll No.-14481SC069

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Contents

• 1.INTRODUCTION TO METALLIC GLASS
• 2 .PRESENT WORK
• a. Synthesis of Ce65Al25Co10 Metallic
  Glass.
• b. Characterizations (XRD, TEM,
  DSC,HARDNESS)
• 3.RESULTS AND DISCUSSIONS
• 4.CONCLUSIONS

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INTRODUCTION

• With the advent of material science and so many
  new engineering material are discovered having
  major application in industries.
• This are classified as metals and alloys,
  ceramics, glasses, glass ceramics, composites and
  semiconductor.
• Our presentation is on one of such material which
  is METALLIC GLASS.

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METALLIC GLASSES

• The material which has the properties of both
  metals and glasses is known as metallic glass or
  metglass.
• METALLIC GLASS AMORPHOUS METAL
• Metallic glasses are metal alloy and are a
  special case of amorphous which shows the glass
  transition.
• They have high strength, good magnetic properties
  and better corrosion resistance.

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PREPARATION

• Principle
• Extreme rapid cooling of molten metal alloy
  called quenching . Cooling so rapidly
  that there is no formation of crystalline
  structure forming solid frozen in liquid
  structure. During the process of solidification,
  atoms do not have enough time or energy to
  rearrange for crystal nucleation. Thus, reaching
  the glass transition temperature Tg solidifies
  as metallic glass. Again, upon heating metallic
  glasses shows a reversible glass-liquid
  transition at Tg .

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Conventional solidification

• Cooling a melt slowly
• ? Crystallization

Volume
Tm
Temperature
Liquid state
Solid state
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Production of a metallic glass

• Cooling a melt slowly
• ? Crystallization

To avoid crystallization ? Rapid cooling
Volume
Metallic Glass!
Tm
Temperature
Super cooled Liquid Region (SLR)
Liquid state
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Glass transition temperature(Tg)

• Metallic glass is prepared by cooling a metallic
  liquid having disordered structure.
• rate of cooling is 2 x 106 k/s
• The temperature at which the transition from
  liquid to solid occurs is known as glass
  transition temperature(Tg).

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TECNIQUES OF PREPARATION

• Various rapid cooling techniques such as
  spraying, spinning and laser deposition are used
  for the production of metallic glasses.

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Melt Spinning technique

• Melt spinner contains refractory tube , copper
  disc, induction heater.
• Mixture of alloy has taken in refractory tube and
  is heated to very high temperature by using
  induction furnace.
• The molten alloy is ejected through fine nozzle
  at the bottom of refractory tube.
• Molten alloy is suddenly cooled while that is
  interact with the wheel and that is solidified.
• Thus a ribbon of metallic glass is obtained.

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Melt Spinning
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PROPERTIES

• High strength but lighter in weight.
• They are ductile ,brittle and opaque. Hardness is
  very high.
• The toughness is very high i.e. the fracture
  resistance is very high.
• High elasticity.
• High Corrosion resistance.
• They are soft magnetic materials. As a result,
  easy to magnetization and demagnetization are
  possible.
• Narrow hysteresis loop thus low hysteresis energy
  losses.
• They have high electrical resistivity which leads
  to a low eddy current loss.

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APPLICATIONS

• Metallic glasses are used as transformer core
  material in high power transformers.
• Due to its high electrical resistivity and nearly
  zero temperature coefficient of resistance, these
  materials are used in making ,magneto resistance
  sensor and computer memory.
• As the magnetic property of metallic glass are
  not affected by irradiation they are used in
  making container for nuclear waste disposal.
• These materials are used in preparation of
  magnets for fusion reactors and magnets for
  levitated trains etc.
• Metallic glasses can also be used for making
  watch cases to replace Ni and other metals which
  can cause allergic reactions.

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PRESENT WORK

• In present work we have synthesise and
  characterise the Cerium based amorphous alloy
  Ce65Al25-XCo10GaX(x0) by applying the following
  experimental technique
• Melt Spinning Technique
• X-Ray Diffraction Technique (XRD)
• Electron Microscopy TEM
• Differential Scanning Calorimetry (DSC)
• Hardness Test

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RESULTS AND DISCUSSIONS
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XRD Patterns for the as-synthesized ribbon of
Ce65Al25Co10 metallic glass-
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Bright field TEM micrograph of as-synthesized
ribbon of Ce65Al25Co10 metallic glass-
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Selected area diffraction pattern of
as-synthesized ribbon of Ce65Al25Co10 metallic
glass-
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Differential Scanning Calorimetry (DSC) profile
of as-synthesized ribbon of Ce65Al25Co10 metallic
glass-
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Hardness test for the as-synthesized ribbon of
Ce65Al25Co10 metallic glass

• In present study the micro-hardness measurements
  were carried out by Vickers's indenter using a
  micro-hardness tester.

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Optical micrographs of the indentation marks for
the as-synthesized ribbon of Ce65Al25Co10
metallic glass -
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Variation of Hardness (VHN) with respect to load
(g) for the as-synthesized ribbon of Ce65Al25Co10
metallic glass -
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Log(P) vs Log(d) plot for the as-synthesized
ribbon of Ce65Al25Co10 metallic glass -
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Conclusions

• In present study we have synthesise and
  characterise the Ce65Al25Co10 Metallic Glass.
  From the present investigation the following
  conclusion can be drawn -
• The XRD pattern shows the single broad
  diffraction maxima within the angular range
  28o37o, characteristic of amorphous phase
  without any detectable sharp peaks.
• TEM micrograph showing contrast free (the absence
  of residual contrast in the bright field image)
  region and corresponding selected area
  diffraction pattern (SADP) displaying presence of
  diffuse halos. This is the characteristic of
  amorphous samples, because of the lack of
  periodicity or long range order in it.

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Conclusions

• In DSC profile a smeared endothermic peak of the
  glass transition is observed temperature 3710 K.
• Hardness measurement shows that the hardness
  decreases with increase in the load due to
  indentation size effect. The Vickers hardness
  (VHN) and yield strength for the Ce65Al25Co10
  alloy have been found to be 2.81 and 1.21 GPa
  respectively.
• Optical micrographs of indentation mark shows the
  wavy like patterns around the indentation
  periphery reveal the formation of shear bands.
  These micrographs revealed that the indentation
  impressions that are regular and crack free at
  load up to 100 g for alloy. However, crack was
  observed at 200 g.

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