Chapters. 11 and 12

Define Jominy end-quench test

A standardized laboratory test that is used to asses the hardenability of ferrous alloys.

Define Overaging

During precipitation hardening, aging beyond the point at which strength and hardness are at their maxima

Define Cast Irons

generically, a ferrous alloy, the carbon content of which is greater than the maximum solubility in austenite at the eutectic temperature. Most commercial cast irons contain between 3.0 and 4.5 wt % C, and between 1 and 3 wt% Si.

Define Silicates

Materials primarily made up of silicon and oxygen, specifically Si O_4 tetrahedra (with -4 charge)

Units for viscosity

Poise (P) and Pascal-seconds (Pa s)

Define Solution Heat Treatmet

Step 1 in precipitation hardnening. THe end result of htis step is a solid solution in which all solute atoms are dissolved and only 1 phase remains. Often this phase is supsersaturated and was achieved through quenching.

Define flexural strength

Stress at fracture from a bend (or flexure test). Also known as modulus of rupture, fracture strength, or bend strength (Ceramics)

Define Powder Metallurgy

The fabrication of metal pieces having intricate and precise shapes by the compaction of metal powders, ,followed by a densification heat treatment

Define Octahedral Position

The void space among close-packed, hard sphere atoms or ions for which there are six nearest neighbors. An octahedron (double pyramid) is circumscribed by lines constructed from centers of adjacent spheres.

Define Gray Cast Irons

A cast iron alloyed with silicon in which the graphite exists in the form of flakes. A fractured surface appears gray.

Define Forging

Mechanical forming of a metal by heating and hammering

If plastic deformation were to occur in a noncrystalline ceramic, how would it occur?

Plastic deformation occurs through viscous flow which doesn't have a preferred direction like slip planes for dislocation motion

Define Welding

A technique for joining metals in which actual melting of the pieces to be joined occurs in the vicinity of the bond. A filler metal may be used to facilitate the process

Define Compacted Graphite Cast Iron

A cast iron iron that is alloyed with silicon and a small amount of magnesium, cerium, or other additives, in which the graphite exists as wormlike particles

Define Ductile or Nodular Iron

A cast iron that is alloyed with silicon and a small concentration of magnesium and/or cerium and in which the free graphite exists in nodular form. Sometimes called nodular iron.

Define Bronze

A copper rich copper-tin alloy; aluminum, silicon, and nickel bronzes are also possible

Define Brass

A copper-rich copper-zinc alloy

Define Alloy Steels

A ferrous (or iron based) alloy that contains appreciable concentrations of alloying elements (other than C and residual amounts of Mn, Si, S and P). These alloying elements are usually added to improve mechanical and corrosion-resistance properties.

Define Plain carbon Steels

A ferrous alloy in which carbon is the prime alloying element

Define Drawing

A forming technique used to fabricate metal wire and tubing. Deformation is accomplished by pulling the material through a die by means of a tensile force applied on the exit side.

Define Extrusion

A forming technique whereby a material is forced, by compression, through a die orifice

Define Annealing

A generic term used to denote a heat treatment wherein the microstructure and, consequently, the properties of a material are altered. "Annealing" frequently refers to a heat treatment whereby a previously cold-worked metal is softened by alloying it to recrystallize

Define Stress Relief

A heat treatment for the removal of residual stresses

Define Precipitation Heat Treatment

A heat treatment used to precipitate a new phase from a supersaturated solid solution. For precipitation hardening, it is termed artificial aging.

Define Temper Designation

A letter-digit code used to designate the mechanical and/or thermal treatment to which a metal alloy has been subjected

Define White Cast Iron

A low-silicon and very brittle cast iron in which the carbon is in combined form as cementite;a fractured surface appears white.

Define Hardenability

A measure of the depth to which a specific ferrous alloy ma be hardened by the formation of martensite upon quenching from a temperature above the upper critical temperature

Define Ferrous Alloys

A metal alloy for which iron is the prime constituent

Define Wrought Alloy

A metal alloy that is relatively ductile and amenable to hot working or cold working during fabrication

Define Rolling

A metal-forming operation that reduces the thickness of sheet stock; also, elongated shapes may be fashion using grooved circular rolls

Define Anion

A negatively charged, non-metallic ion

Define Cation

A positively charged metallic ion

Define Stainless Steels

A steel alloy that is highly resistant to corrosion in a variety of environments. The predominant alloying element is chromium, which must be present.

two requirements of an alloy for precipitation hardening

An appreciable maximum solubility on one component in the other on the order of several percent; and a solubility limit that rapidly decreases in concentration of the major component with temperature reduction

Define Process Annealing

Annealing of previously cold-worked products (commonly steel alloys in sheet or wire form) below the lower critical (eutectoid) temperature

Define Hot working

Any metal-forming operation that is performed above a metal's recrystallization temperature

Do brittle ceramics have higher strengths under tension or compression or are they the same?

Compression

How is precipitation hardening accomplished?

First by solution heat treatment, in which all solute atoms are dissolved to form a single-phase solution. Second by precipitation heat treatment, the single phase solution is heated to the correct temperature so that finely dispersed second phase particles form.

Define Upper Critical Tempearture

For a steel alloy, the minimum temperature above which, under equilibrium conditions, only austenite is present

Define Lower Critical temperature

For a steel alloy, the temperature below which, under equilibrium conditions, all austenite has transformed to ferrite and cementite phases

Define Normalizing

For ferrous alloys, austenitizing above the upper critical temperature, the cooling in air. The objective of this heat treatment is to enhance toughness by refining the grain size

Define Full Annealing

For ferrous alloys, austenitizing, followed by cooling slowly to room temperature forming coarse pearlite

Define Stoichiometry

For ionic compounds, the state of having exactly the ratio of cations to anions specified by the chemical formula

Define artificial aging

For precipitation hardening, aging above room temperature

Define natural aging

For precipitation hardening, aging at room temperature

Define Spheroidizing

For steels, a heat treatment normally carried out at a temperature just below the eutectoid in which the spheroidite microstructure is produced.

Define Austenitizing

Forming austenite by heating a ferrous alloy above its upper critical temperature- to within the austenite phase region from the phase diagram

Define Precipitation Hardening

Hardening and strengthening of a metal alloy by extremely small and uniformly dispersed particles that precipitate from a supersaturated solid solution; sometimes also called age hardening

Define Shottky Defect

In a ionic solid, a cation-vacancy and anion vacancy pair

Define Frenkel Defect

In a ionic solid, a cation-vacancy and cation interstitial pair.

Define Defect Structure

Relating to the kinds and concentrations of vacancies and interstitials in a ceramic compound

Define High Strength, Low-alloy steels (HSLA)

Relatively strong, low carbon steels, with less than about 10 wt% total of alloying elements

Define Cold Working

The plastic deformation of a metal at a temperature below that at which it recrystallizes

Define Specific Strength

The ratio of tensile strength to specific gravity for a material

Define viscosity (eta)

The ratio of the magnitude of an applied shear stress to the velocity gradient that it produces; that is, a measure of a non-crystalline material's resistance to permanent deformation

Define Electroneutrality

The state of having exactly the same numbers of positive and negative electrical charges (ionic and electronic)- that is, of being electrically neutral

Define Tetrahedral Position

The void space among close-packed, hard sphere atoms or ions for which there are four nearest neighbors.

Why are anion interstitials so uncommon in ceramics?

There size means if they did occupy an interstitial site, there would be a lot of unfavorable lattice distortion

If plastic deformation were to occur in a crystalline ceramic, how would it?

Through dislocation motion along slip planes (though unlikely due to ions interacting that are repulsive to one another or covalent bonds being soo strong)

Define Malleable Iron

White cast iron that has been heat treated to convert the cementite into graphite clusters; a relatively ductile cast iron

What is a fullerene?

a form of carbon having a large spheroidal molecule consisting of a hollow cage of atoms, of which buckminsterfullerene was the first known example