metals and composites

Question 1

the 4 types of engineering materials

Answer 1

metals, ceramics, polymers, composites

Question 2

4 advantages of metals

Answer 2

high stiffness and strength
toughness
good electrical and thermal conductivity
cost effective

Question 3

Metals can be {1} for high hardness, strength and {2}

Answer 3

1: alloyed
2: rigidity

Question 4

what’s meant by toughness

Answer 4

capacity to absorb energy

Question 5

what material has greater thermal conductivity than respective materials

Answer 5

metals, compared to ceramics and polymers

Question 6

ferrous metal meaning

Answer 6

based on iron e.g. steel, cast iron

Question 7

superalloys are based on {1}, nickel or {2}

Answer 7

1: iron
2: cobalt

Question 8

Alloying can enhance material {1}. Alloying can increase {2} and {3} relative to pure metals.

Answer 8

1:properties
2, 3: strength, hardness

Question 9

define hardness

Answer 9

ability to withstand surface indentation

Question 10

alloying is …

Answer 10

mixture/compound of 2+ elements, at least one being metallic

Question 11

2 main alloying categories

Answer 11

solid solutions
intermediate phases

Question 12

solid solutions means…

Answer 12

alloy where one element is dissolved in another, forms a single phase structure

Question 13

what’s meant by a phase

Answer 13

any homogenous mass e.g. metal, in which grains have the same crystal lattice structure

Question 14

In solid solution, what material is the solvent or base element? What material is the dissolved element

Answer 14

metallic
metallic or non

Question 15

2 forms of solid solutions, briefly describe

Answer 15

1) substitutional– atoms of solvent element replaced in its unit cell by dissolved element
2) interstitial– atoms of dissolving element fit into vacant spaces between base metal atoms in lattice structure

Question 16

In both solid solution forms, alloy structure is generally {1} and {2} than either of the component elements

Answer 16

1,2 : stronger, harder

Question 17

There’s usually limits to the {1} of one element in another. When the amount of {2} element in the alloy exceeds the solid {1} limit of the {3} metal, a {4} phase forms in the alloy. I.e. the chemical composition is {5} between the two {6} elements.

Answer 17

1: solubility
2: dissolving
3: base
4: second
5: intermediate
6: pure

Question 18

Metallic compounds are an example of {1} phases, consisting of…

Answer 18

1: intermediate
metal and non metal e.g. iron carbide, Fe3C

Question 19

Intermetallic compounds are …, such as …

Answer 19

two metals forming a compound e.g. Roman yellow brass, CuZn

Question 20

For intermetallic compounds, describe structure and properties

Answer 20

1) intermetallic–well defined stoichiometry (elements combine in fixed, precise ratios) and ordered crystal structures, form when 2=+ metals combine in specific atomic ratios
properties–high hardness and temp resistance

Question 21

Intermetallic compounds tend to be more brittle due to their { 1 }. They display unique superconducting, chemical and {2} properties due to their { 3 } and mixed bonding (metallic and {4})

Answer 21

1: more ordered structure
2: magnetic
3: more ordered structure
4: ionic

Question 22

For metallic compounds, describe structure and properties

Answer 22

mix of 2=+ metals (or metals and another element), where combined metals retain some of their individual properties
more ductile and malleable than intermetallic
varying melting point
designed to harness best properties of constituent metals e.g. improved strength, corrosion resistance

Question 23

{1} compounds are widely used in various industries due to their customizable properties, such as construction, {2} and {3}

Answer 23

1: metallic
2, 3: aerospace, automotive

Question 24

Intermetallic compounds are known for their high { 1 } and unique magnetic and chemical properties, they are generally more {2}. Metallic compounds, on the other hand, are valued for their {3}, malleability, and {4} properties.

Answer 24

1: melting points
2: brittle
3: ductility
4: customizable

Question 25

Two phase alloys are important as they can be { 1 } for much higher strength than { 2 }

Answer 25

1: heat treated 2: solid solutions

Question 26

eutectic alloy meaning

Answer 26

mixture 2=+ elements that has specific composition st it solidifies at single lower temperature, eutectic point// solidus and liquidus at same temp

Question 27

Eutectic, derived from the Greek word eutektos, meaning easily {1}. Eutectic temperature is the { 2 } of the eutectic composition, always the {3} { 2 } for the alloy system.

Answer 27

1: melted 2: melting point 3: lowest

Question 28

2 most important ferrous metals

Answer 28

alloys of iron and carbon (superior strength)

Question 29

iron and carbon alloys divided into two major groups:

Answer 29

steel and cast iron, make approx 85% of metal tonnage

Question 30

For iron, the phase at room temperature is alpha, called {1} which is a BCC/FCC. At {2} degrees, ferrite transforms to gamma, called {3} which is a BCC/FCC. Then from 1394 degrees, this transforms to delta, BCC/FCC.

Answer 30

1: ferrite, BCC 2: 912 3: austenite, FCC FCC

Question 31

pure iron melts at

Answer 31

1540 degrees

Question 32

the most pure iron is {1} iron, at about x%, for research and other purpose where pure metal is required.

Answer 32

1: electrolytic 99.99

Question 33

{1} iron contains 0.1% impurities, and is used in applications where high {2} or { 3 } is needed

Answer 33

1: ingot 2,3: ductility, corrosion resistance

Question 34

{1} iron is contains 3% slag, but very little carbon, and is easily shaped in hot forming operations such as {2}

Answer 34

1: wrought 2: forging

Question 35

Ferrite/Austenite dissolves more carbon than ferrite/austenite. The difference in {1} between alpha and gamma provides opportunities for strengthening via {2} treatment

Answer 35

Austenite, ferrite solubility heat

Question 36

what are superalloys?

Answer 36

High performance alloys designed to meet demanding requirements for strength & resistance to surface degradation at high temps

Question 37

Many superalloys contain substantial amounts of {1} or more metals, rather than one base metal +alloying elements. Superalloys are very {in/expensive}, and are technologically important due to their { 2 }.

Answer 37

1: 3 2: unique properties

Question 38

For super alloys, {room/high} temperature performance is good, while {room/high} temp performance is excellent

Answer 38

room, high

Question 39

For superalloys, {1} temperature performance is excellent - tensile strength, hot hardness, {c__ & c___} resistance, and at very {1} temperatures Operating temperatures often ~ {2} ºC. Applications e.g. {3}, for any system operating more {4} at {5} temperatures

Answer 39

1: high corrosion, creep 3: jet and rocket engines, steam turbines, and nuclear power plants 4: efficiently 5: elevated

Question 39

True or false, superalloys excel in systems that operate more efficiently at high temperatures

Answer 39

true

Question 40

three groups of superalloys

Answer 40

iron based e.g. alloyed with Ni nickel based, better high temp strength than alloy steels, alloyed with Fe, Ti cobalt based

Question 41

all superalloys strengthen by { 1 }

Answer 41

precipitation hardening

Question 42

common process for steel making

Answer 42

basic oxygen furnace electric furnace

Question 43

three metal shaping processes

Answer 43

casting, powder metallurgy, deformation, material removal

Question 44

metal parts are joined to form assemblies by {1, 2 ,3 }

Answer 44

welding, soldering, mechanical fastening

Question 45

heat {1} is used to enhance properties

Answer 45

treating

Question 46

finishing processes (e.g. {1} & {2}), are used to improve appearance of metal parts and/or provide { 3 }

Answer 46

1: painting, electroplating 3: corrosion protection

Question 47

3 methods to enhance metal properties

Answer 47

alloying, cold working, heat treatment

Question 48

Cold working, involves { 1 } during {2} to increase strength, reduces {3}. Heat treatment involves heating and {4} {5} performed to beneficially change its {6} properties.

Answer 48

1: strain hardening 2: deformation 3: ductility 4: cooling 5: cycles 6: mechanical

Question 49

heat treatments, cold working and alloying work by altering the metals {1} which in turn determines its {2}

Answer 49

1: microstructure 2: properties

Question 50

Greatest use in manufacturing for silicon is in ceramics (e.g. {1} in glass and {2} in clays), and alloying elements in e.g. {3}. {4} silicon is of significant technological importance as the base material in {5} manufacturing in electronics.

Answer 50

1: SiO2 2: silicates 3: steel, cast iron, Al, Cu 4: Pure 5: semiconductor

Question 51

2 basic categories of processing ceramics

Answer 51

molten and particulate