A Presentation on Metallic Glasses

-by Dhaval Shukla (141080119050)-Mechanical Branch-2nd Semester-Prof. Medha Shah

Metallic Glasses

IntroductionMetallic Glasses are the newly

developed engineering materials.Metallic Glasses share the properties of

both metals and alloys.Most metals and alloys are crystalline,

i.e., their atoms are arranged in some regular pattern that extends over a long distance.

In contrast, glass is an amorphous (non-crystalline), brittle and transparent solid.

Introduction

1. Crystalline : We can see that crystal atoms have equal gap from each other thus forms a strong bond of contact.

2. Polycrystalline : Polycrystalline atoms have less contact or bonding than the crystalline atoms.

3. Amorphous : These structure forms the metallic glass.

Introduction

Crystalline Properties of Most Metals

IntroductionThus, metallic glasses are metal

alloys that are amorphous.That is, they don’t have a long

range atomic order.The major advantage of such

glasses are that they are generally homogeneous in composition, and offer strong and superior corrosion resistance.

IntroductionTo have this peculiar property,

metallic glasses are to be made by cooling a molten metal rapidly at a rate of

During this process of solidification, the atoms do not have enough time to rearrange for crystal nucleation.

Thus, the liquid upon reaching the glass transition temperature solidifies as metallic glass.

6 12 10 Cs .

Tg

IntroductionAgain, upon heating, metallic

glasses show a reversible glass-liquid transition at

T .g

Types of Metallic GlassesMetallic Glasses are of two types

depending on the base material used for preparation.

1. Metal – Metal glasses.Examples: Ni-Nb, Mg-Zn and Cu-Zr.2. Metal – Metalloid glasses.Transition metals like Fe, Co, Ni and

metalloids like B, Si, C and P are used.

Examples: 67 18 14 40 38 4 18 66 4

14 15

Fe Co B Si, Fe Ni Mo B , and Co Fe Ni,B Si , etc.

Types of Metallic GlassesCommercial metallic glasses are

usually of this type.

Difference between Metallic and Non-metallic materials

Metallic

Made up of metals

They are very strong

They are easily

magnetized

Very low hysteresis

losses

Non-metallic

Made up of non-metals

Not much stronger

comparatively

Can’t be easily

magnetized

No hysteresis

curve

Production of Metallic Glasses

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

In this technique, there is a spinning disc made of copper.

Melt Spinning Process Technique

Production of Metallic GlassesIn order to prepare a metallic

glass of a particular type, a suitable combination of metal-metal or metal-metalloid alloy in its preferred ratio is taken in a refractory tube having a fine nozzle at its bottom.

The nozzle side of the tube is placed just over the spinning disc.

Production of Metallic Glasses

Production of Metallic Glasses

Spinning Copper disc

Production of Metallic Glasses

Refractory tube

Production of Metallic Glasses

Rotating Roller

Production of Metallic Glasses

Molten Alloy

Production of Metallic GlassesAn induction heater attached to

the refractory tube melts the alloy.

This melt is kept above its melting point till it gets transformed into a homogeneous mixture.

An inert gas such as helium is made to flow through the tube containing the homogeneous mixture.

Production of Metallic GlassesAs a result the melt gets rejected

through the nozzle.The ejected melt is cooled at a faster

rate with the help of the spinning cooled copper disc.

The ejection rate can be increased by increased by increasing the pressure of the inert gas.

Thus, a glassy alloy ribbon may be varied by increasing or decreasing the speed of the spinning disc.

Production of Metallic Glasses

As fast the spinning wheel will be the faster will be the cooling effect on the melt alloy.

Properties1. The strength of metallic glasses

is very high (nearly twice that of stainless steel) but they are lighter in weight.

2. They are ductile, malleable, brittle and opaque. The hardness is very high.

3. The toughness is very high. i.e., the fracture resistant is very high (more than ceramics).

Properties

Ceramics have very higher fracture resistant, but the metallic glasses are of even higher fracture resistant.

Ceramics

Metallic Glasses

Properties4. They have high elasticity. i.e.,

the yield strength is high.5. They have high corrosion

resistance.6. They do not contain any

crystalline defects like point defects, dislocation, stacking faults, etc.

PropertiesCrystal materials have point defects the advantage of metallic glasses is that they don’t have any kind of defects like crystalline structures.

Properties7. They are soft magnetic materials. As a

result, easy magnetization and demagnetization are possible.

8. Magnetically soft metallic glasses have very narrow hysteresis loop. Thus, they have very low hysteresis energy loss.

9. They have a high electrical resistivity which leads to a low eddy current loss.

The last two properties of metallic glasses makes it possible for them to be used as a transformer.

PropertiesA very narrow hysteresis loop found in metallic glasses profits into very low hysteresis energy losses.

Applications1. Metallic glasses are used as

transformer core material in high-power transformers.

Usage of metallic glasses in transformers is found to improve the efficiency of power distribution in transformers.

These transformers are used to convert high-voltage current into low-voltage current to be used for domestic appliances (120 V and 240 V).

ApplicationsMetallic Glasses are used as Transformer core material

ApplicationsCompared to conventional

transformers, the power transformers with metallic glasses as core is found to help in reducing the core loss.

In addition, the size and weight are also very less. The loss is less in the latter case because of its ferromagnetic property with low hysteresis loss and high electrical resistivity property.

Applications2. Because of their high electrical

resistivity and nearly zero temperature coefficient of resistance, these materials are used in making cryothermometers, magnetoresistance sensors and computer memories.

3. As the magnetic properties of the metallic glasses are not affected by irradiation they are used in making containers for nuclear waste disposal.

Applications

Due to nearly zero temperature coefficient of resistance the metallic glasses are used in the production of cryo thermometers and magnetoresistive sensors.

Applications

Due to the quality of irradiation of metallic glasses they are used in containers for radioactive disposal

Applications4. These materials are used in the

preparation of magnets for fusion reactors and magnets for levitated trains, etc.

5. Metallic glasses can also be used for making watch cases to replace Ni and other metals which can cause allergic reactions.

6. The excellent corrosion resistance property makes these materials ideal for cutting and in making surgical instruments.

Applications

The metallic glasses are used to make magnets which are used in levitated trains as the medium of transportation

ApplicationsIn addition, they can be used as a

prosthetic material for implantation in the human body.

7. In future, the usage of metallic glasses in the electronic field can yield stronger , lighter and more easily moulded castings for personal electronic products.

8. Metallic glasses are used in tap recorders as heads, in the manufacture of springs and standard resistances.

ApplicationsIn future there will be a very positive deal of the use of metallic glasses in electronic field.

The End

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