Materials Science Flashcards
Define material strength
The ability of a material to resist deformation
Define Metallic Bond
Atoms do not share or exchange electrons. Instead, many electrons (roughly one for each atom) are free to move throughout the metal.
Define edge dislocation
Consists of an extra row or plane of atoms in the crystal structure
Define hardness
The property of a material that enables it to resist plastic deformation, penetration, indentation, and scratching
What are the desirable properties of 304 stainless steel
- Extremely tough
- Corrosion resistant
Define ductility
The ability of a material to deform easily on application of a tensile force
Define screw dislocation
Develop by a tearing of the crystal parallel to the slip direction
Define yield strength
The stress at which the material transitions from elastic to plastic deformation
An imperfection that results from a missing atom in a lattice position is a _____________ defect
Vacancy defect
Describe fatigue failure
A material’s tendency to fracture by means of progressive brittle cracking under repeated altering or cyclic stresses of an intensity considerably below the normal strength
Describe annealing of a metal
A common heat treatment process that occurs slowly to an elevated temperature where it is held for a period of time and then cooled to relieve stress and improves ductility
What characteristics are typical of alloys
- Stronger than pure metals
- Reduced electrical conductivity
- Reduced thermal conductivity
Define Covalent Bond
Bond formed when two elements share electrons
Describe heat treatment of a metal
The heating of a component to take advantage of metallic crystalline structures and their effects on the metal to gain desirable properties
Name three types of point imperfections
- Vacancy defects
- Substitutional defects
- Interstitial defects
Define Hydrogen Bond
Similar to a molecular bond but occurs due to the ease with which hydrogen atoms are willing to give up an electron to atoms of oxygen, fluorine, or nitrogen
Eight atoms at the corners of a cube and one atom at the center of the cube describes a _____________ lattice-type structure
Body Centered Cubic (BCC)
Define macroscopic material defects
- Defects that are three dimensional and on the macroscopic scale. Introduced to a material during refinement from its raw state or during fabrication.
- Most common bulk defects are called inclusions.
Describe creep
The ability of a material to deform under constant stress or load
Define mixed dislocation
Some combination of edge and screw dislocations
Name three types of microscopic imperfections
- Point imperfection
- Line imperfection
- Interfacial imperfection
An imperfection that results from an impurity, or a lattice atom, at an interstitial site
Interstitial defect
Describe the relationship between grain size and tensile strength, ductility, and creep
- Smaller grain size increases tensile strength and ductility.
- Larger grain size improves high temperature creep properties.
Body Centered Cubic (BCC) structures have what properties
- High Strength
- Low Ductility
Hexagonal Close-Packed (HCP) structures have what properties
Not as ductile as FCC metals
Describe work hardening
Occurs when straining a metal beyond the yield point to plastic deformation which causes the metal to become stronger and more difficult to form
An imperfection that results from an impurity at a lattice position is a ________________ defect
Substitutional defect
Define ultimate tensile strength
- The maximum resistance a material presents to fracture.
- The peak of the stress/strain curve
A mixture of two or more materials, at leas one of which is a metal, is called a ____________
Alloy
Describe cold working of a metal
Plastic deformation of a metal below the crystallization temperature which decreases ductility and increases strength by reducing the materials grain size without relieving the strain hardening
Define Ionic Bond
One or more electrons is wholly transferred from an atom of one element to the atom of another element
Describe hot working of a metal
Plastic deformation of a metal above the crystallization temperature which increases strength without reducing ductility since strain hardening is relieved
Materials that are arranged in a pattern that periodically repeats in a three dimensional geometric lattice are said to be ______________ solids
Crystalline
Eight atoms at the corners of a cube and one atom at the center of each of the faces of the cube describes a _____________ lattice-type structure
Face Centered Cubic (FCC)
Describe quenching of a metal
The controlled cooling of a metal to take advantage of metallic crystalline structures and their effects on the metal to gain desirable properties
Define malleability
The ability of a material to display large deformation when subjected to a compressive force
Define Molecular Bond
When a temporary weak charge is created by electrons of neutral atoms spending more time in one region of their orbit than another, the molecule weakly attracts other molecules with similar weak charges.
Define toughness
The work required to deform one cubic inch of metal until it fractures
Materials that have no regular arrangement of atoms or molecules are said to be _____________ materials
Amorphous
Face Centered Cubic (FCC) structures have what properties
- Lower strength than BCC
- Higher ductility than BCC
Three layers of atoms with the top and bottom layers containing six atoms at the corners of a hexagon and one atom at the center of each hexagon and the middle layer containing three atoms nestled between the atoms of the top and bottom layers describes a ________________ lattice-type structure
Hexagonal Close-Packed (HCP)
______________ imperfections can only occur in crystalline materials, can include edge, screw, and mixed types, and are also called dislocations
Line imperfection
