Exam 1

Question 1

Engineering Materials

Answer 1

Polymers, Ceramics, Metals, Composites

Question 2

Proton

Answer 2

Subatomic particle. Have mass and positive charge

Question 3

Neutron

Answer 3

Subatomic particle. Have mass and neutral charge

Question 4

Electron

Answer 4

Subatomic particle. Have a negative charge.

Question 5

Valence Electrons

Answer 5

Electrons in the outer orbit (shell) of an atom. These electrons largely determine the chemical properties of an element.

Question 6

Ionic Bonding

Answer 6

Chemical bond between atoms in which one atom gives up valence electrons to become a positive ion and another atom gains valence electrons to become a negative ion. Bonded electrostatically.

Question 7

Covalent Bonding

Answer 7

Chemical bond between atoms in which atoms share valence electrons in order to fill the outer electron orbit (shell) of both atoms. This sharing of electrons then bonds the atoms together.

Question 8

Metallic Bonding

Answer 8

Chemical bond between atoms in which atoms give up valence electrons to form an electron matrix (electron cloud) and positive ions. The atoms are bonded together by the electrostatic attraction between the positive ions and the negative electrons on the matrix. “Blank” bonding gives metals their unique characteristics.

Question 9

Van Der Wall Forces

Answer 9

Weak secondary inter-atomic attractions arising from internal dipole effects (electrostatic).

Question 10

Element

Answer 10

A pure substance that cannon be broken down into other substances by chemical means.

Question 11

Alloy

Answer 11

A material that has metallic characteristics and is composed of two or more elements, of which at least one is a metal.

Question 12

Structure

Answer 12

The manner in which atoms are arranged in a metal or alloy.

Question 13

Chemical Properties

Answer 13

Material characteristics related to the structure of a material with each other and with various forms of energy.

Question 14

Physical Properties

Answer 14

Material characteristics pertaining to the interaction of materials with each other and with various forms of energy.

Question 15

Mechanical Properties

Answer 15

Material characteristics that are seen when a mechanical force is applied to the materials.

Question 16

Service Failures

Answer 16

Engineering materials fail in service by one of the following three methods: Corrosion, Wear, or Mechanical Overload

Question 17

Crystal Lattice Structures

Answer 17

Orderly and specific arrangement of atoms in a series of unit cells. Three common metal types are BODY CENTERED CUBIC, FACE CENTERED CUBIC, HEXAGONAL CLOSE PACKED

Question 18

Amorphous Structures

Answer 18

Solid materials that do not have a repeating orderly arrangement of their atoms.

Question 19

Nucleus

Answer 19

The starting point of a crystal grain growth as the metal solidifies.

Question 20

Dendric

Answer 20

The tree-like manner in which a metal crystal grows from he nucleus into the grain during solidification.

Question 21

Grain

Answer 21

Metal crystals with an irregular three dimensional, external shape and an orderly, specific internal atomic arrangement (crystal lattice structure).

Question 22

Phase

Answer 22

A physically homogeneous portion of a material. Has the same structure throughout it, roughly the same composition and properties throughout it, and an interface between it and other phases.

Question 23

Allotropic Change

Answer 23

The change of a metal from one crystal lattice structure to another in the solid state.

Question 24

Dislocations

Answer 24

Imperfections on an atomic scale within the crystal lattice structure that allows plastic deformation to occur.

Question 25

Slip Planes

Answer 25

The closest packed atomic planes in the crystal lattice. These are the planes that dislocations move along.

Question 26

Cold Working, Work Hardening, Strain Hardening

Answer 26

Plastic deformation of a metal below the recrystallization temperature. The changes produced by the work on the crystal lattice structure remain as distorted atoms. 1 f the 4 major methods of increasing strength in materials.

Question 27

Hot Working

Answer 27

Plastic deformation of a metal above the recrystallization temperature. The metal is constantly being annealed.

Question 28

Annealing

Answer 28

Three stage process of restoring cold worked metal to its original soft, unstained conduction. The three stages are recovery, recrystallization, and grain growth. This is a softening process.

Question 29

Recrystallization

Answer 29

The lowest temperature at which the distorted grain structure of a cold worked metal changes to a new, strain free non-distorted structure.

Question 30

Stress

Answer 30

Load on a body distributed over the body's cross-sectional area, or force per unit area. (Units of Pascals or psi)

Question 31

Strain

Answer 31

Deformation of a body under stress, measured in units of change in length per unit length. (in/in)

Question 32

Elastic Strain

Answer 32

Strain that disappears on removal of the stress that caused it.

Question 33

Plastic Strain

Answer 33

Strain that remains on removal of the stress that caused it.

Question 34

Elongation

Answer 34

Deformation of a body under stress, measured in terms of total change in length.

Question 35

Static Load

Answer 35

Load imposed without motion, acting by weight alone.

Question 36

Dynamic Load

Answer 36

Load imposed with both weight and motion (impact).

Question 37

Hardness

Answer 37

The ability of a material to resist penetration or indentation. Rockwell and Brinell are common hardness testing methods.

Question 38

Strength

Answer 38

The material's ability to resist deformation (or fracture) from applied stress.

Question 39

Plasticity

Answer 39

The ability of a material to deform without fracture. Two types of plasticity are Ductility and Malleability.

Question 40

Brittleness

Answer 40

The tendency of a material to fracture suddenly without plastic deformation. The opposite of plasticity.

Question 41

Yield Strength

Answer 41

The stress that will produce a specified amount of plastic strain in a material.

Question 42

Modulus of Elasticity

Answer 42

Measure of resistance to elastic deformation. The higher the modulus of elasticity, the lower the amount of strain for a given amount of stress, and the more "elastically stiff" the material.

Question 43

Elastic Limit

Answer 43

The point in tensile loading where strain is no longer proportional to the applied stress. (end of elastic region)

Question 44

Ductility

Answer 44

Plasticity of a metal under tensile stress.

Question 45

Malleability

Answer 45

Plasticity of a metal under compressive stress.

Question 46

Toughness, Impact Strength

Answer 46

The ability of a metal to absorb energy without fracture. Toughness is a combination of strength and ductility. Izod and Charpy...

Question 47

Resilience

Answer 47

The ability of a metal to absorb energy without plastic deformation. Combination of strength and elasticity.

Question 48

Shear Strength

Answer 48

The stress required to produce fracture in a plane of the cross section of the material.

Question 49

Creep Strength

Answer 49

The constant nominal stress that will cause a specified quantity of creep in a given time at a specified temperature.

Question 50

Fractures or Failures

Answer 50

4 common mechanical types of overload fractures are brittle, ductile, fatigue and creep.

Question 51

Endurance Limit

Answer 51

The maximum stress below which a material can withstand an infinite number of stress cycles. Steels and Titanium alloys have endurance limits.

Question 52

Fatigue Strength

Answer 52

The stress that will cause fatigue fracture after a set number of stress cycles. Used for Aluminum alloys and other non-ferrous metals.

Question 53

Why do atoms bond?

Answer 53

To reach their lowest energy state

Question 54

Common Crystal Defects

Answer 54

Vacancy and Dislocation

Question 55

D.B.T.T.

Answer 55

Ductile to Brittle Transition Temperature