Metals in mouth

Question 1

What type of bonding gives crystalline structure

Answer 1

Metallic

Question 2

Name 2 properties a metal should have for human use

Answer 2

corrosion resistant, biologically inert

Question 3

Name 4 issues we must compensate for in lost wax technique

Answer 3

• Shrinkage of wax
• Shrinkage of metal cast
• Setting expansion of investment metal
• Thermal expansion of metal

Question 4

Define phase

Answer 4

Structurally homegonous part of system with CLEAR PHYSICAL BOUNDARIES

Question 5

What is the latent heat of fusion

Answer 5

When crystallisation of metals happen and there is heat and energy released

Question 6

What do crystals grow from?

Answer 6

nuclei grow to form crystals

Question 7

What do crystals make?

Answer 7

Grain

Question 8

What is the smallest atom in a crystal?

Answer 8

Unit cell

Question 9

What is the pattern of atomic arrangement in crystals?

Answer 9

Atomic arrangement is repeated at regular intervals in 3D

Question 10

How are the various crystalline systems arranged

Answer 10

Axially

Question 11

How many axes does each lattice system have

Answer 11

3

Question 12

What are the 7 types of lattice systems?

Answer 12

Cubic, Tetragonal, Orthorhombic, Rhombohedral, Hexagonal, Monoclinic and tri clinic

Question 13

What is packing factor?

Answer 13

Volume of atoms inside cube/Volume of cube

Question 14

What has a higher packing factor: Simple cubic or Face Centred

Answer 14

Face centred packs more atoms: 0.74 and Simple= 0.52

Question 15

How can we visulaise grains

Answer 15

Etch

Question 16

What does faster cooling of metal lead to/

Answer 16

Finer grains

Question 17

What does electron beam heating do?

Answer 17

Resolidifies metal and grain GROWTH

Question 18

How to investigate properties of alloys?

Answer 18

Phase diagrams

Question 19

How is the temperature in crystallisation of a pure metal after heating?

Answer 19

Temperature is constant in crystallisation

Question 20

How is the temperature in crystallisation of an alloy?

Answer 20

Temperature varies as the metals crystallise at different temps

Question 21

What happens when we reheat an alloy?

Answer 21

There is diffusion of grains as there is homogenisation of grains

Question 22

Name 3 types of alloys?

Answer 22

Solid, Intermetallic,Eutectic

Question 23

What are the 2 types of solid solutions?

Answer 23

Substitutional and Interstitial

Question 24

What happens to metals in a solid solution

Answer 24

They completely mix

Question 25

What happens to metals in intermetallic?

Answer 25

There are specific sites for each atom within the lattice

Question 26

What are properties of solid solution?

Answer 26

Enhance ductility

Question 27

What are properties of intermetallic?

Answer 27

Increased hardness and brittle

Question 28

Properties of eutectic?

Answer 28

Weak and corrodes

Question 29

Why are there 2 types of solid solutions?

Answer 29

As it depends on size of solute particles

Question 30

When do we get substitutional solids?

Answer 30

Solute particle DIRECTLY substitutes solvent particle. - Atoms have similar valency - Atom size within 15% of each other - Atoms have similar crystal structure

Question 31

Gimme example of substitutional solid?

Answer 31

Gold and copper

Question 32

When do we get intestitial solid solutions

Answer 32

When solute atoms take small space between solvent atoms | -Solute atoms must be 60% smaller than solvent atoms

Question 33

Gimme example of Interstitial solid

Answer 33

Steel+Carbon

Question 34

How do we get intermetallic compound

Answer 34

2 metals react to form a new component at a stoichiometric ratio

Question 35

Give example of intermetallic compound

Answer 35

Amalgam

Question 36

What state of matter do intermetallic compounds form in

Answer 36

Can happen in solids as we get diffusion in metals

Question 37

What happens in Diffusion of metals

Answer 37

Exchange of position of atoms in lattice

Question 38

Why do eutectic alloys form?

Answer 38

As some metals are completely insoluble in metal phase.

Question 39

How is eutectic alloy similar to a pure metal?

Answer 39

Crystallises at a specific temperature as opposed to over a range of temperatures

Question 40

What can rapid cooling of alloys give?

Answer 40

Separation of metals

Question 41

What does homogenous annealing do?

Answer 41

Uniform microstructure

Question 42

What type of structure is formed when metals resolidify?

Answer 42

Dendritic

Question 43

How do we get deformation of grains?

Answer 43

1. Distort lattice | 2. Slip

Question 44

Define slip

Answer 44

Movement of vacacines, imperfections to the edge of structure

Question 45

What happens when we deform metal?

Answer 45

Increased yield strength increased hardness -Th crystals will WARP

Question 46

Name 3 types of imperfections in a ALLOY lattice?

Answer 46

- Substitutional atom - Interstitial atom - Vacancy

Question 47

What happens when we beat out imperfections in slip?

Answer 47

The imperfections move through metal one plane at a time. The force applied does not cause fracture/failure of lattice

Question 48

What happens to the lattice structure when we make a wrought alloy?

Answer 48

It gets DEFORMED | -We exceed elastic limit of metal

Question 49

What is residual stress? (Strain hardening)

Answer 49

Occurs in the grains when we have distorted the lattice and caused grain deformation

Question 50

What type of lattice in a wrought allow

Answer 50

Deformed

Question 51

What happens when we heat wrought structure? (Annealing)

Answer 51

Grain Growth Grain relaxation Diffusion of atoms

Question 52

How much stress is there in an extensively wrought structure?

Answer 52

More residual stress as more deformation to the lattice

Question 53

Temperature or recrystallization in an extensively wrought structure?

Answer 53

Lower

Question 54

Japanese Katana sword. Fast cool of steel gives? Slow cool of steel gives?

Answer 54

Fast=Martinsite | Slow= Pearlite

Question 55

What steel in sword is softer and tougher

Answer 55

Pearlite

Question 56

What material controls the cooling rate of the steel in the sword?

Answer 56

Clay