Matsci Ezam 3
Chapter 9
Austenite: Face-centered cubic iron; also iron and steel alloys that have the FCC crystal structure.
Cementite: Iron Carbide
eutectoid reaction:A reaction in which, upon cooling, one solid phase transforms isothermally and reversibly into two new solid phases that are intimately mixed.
eutectic structure: A two-phase microstructure resulting from the solidification of a liquid having the eutectic composition; the phases exist as lamellae that alternate with one another.
Eutetic reaction: A reaction in which upon cooling, one liquid phase transforms isothermally and reversibly into two new solid phases that are intimately mixed.
Ferrite:Body-centered cubic iron; also iron and steel alloys that have the BCC crystal structure.
hypereutectoid alloy: For an alloy system displaying a eutectoid, an alloy for which the concentration of solute is greater than the eutectoid composition.
to the right
Isomorphous: Having the same structure. In the phase diagram sense, isomorphicity means having the same crystal structure or complete solid solubility for all compositions
lever rule: A mathematical expression, such as Equation 9.1b or Equation 9.2b, by which the relative phase amounts in a two-phase alloy at equilibrium may be computed.
liquidus line: On a binary phase diagram, the line or boundary separating liquid- and liquid + solid-phase regions. For an alloy, the liquidus temperature is the temperature at which a solid phase first forms under conditions of equilibrium cooling.
Microconstituent: An element of the microstructure that has an identifiable and characteristic structure. It may consist of more than one phase, such as with pearlite.
Pearlite: A two-phase microstructure found in some steels and cast irons; it results from the transformation of austenite of eutectoid composition and consists of alternating layers (or lamellae) of -ferrite and cementite.
phase: A homogeneous portion of a system that has uniform physical and chemical characteristics.
proeutectoid ferrite: Primary ferrite that exists in addition to pearlite for hypoeutectoid steels.
proeutectoid cementite: Primary cementite that exists in addition to pearlite for hypereutectoid steels.
solidus line: On a phase diagram, the locus of points at which solidification is complete upon equilibrium cooling, or at which melting begins upon equilibrium heating.
Chapter 14
block copolymer :A linear copolymer in which identical repeat units are clustered in blocks along the molecular chain.
C
branched polymer : A polymer having a molecular structure of secondary chains that extend from the primary main chains.
cross linked polymer :
molecular weight :The sum of the atomic weights of all the atoms in a molecule.
Monomer :A stable molecule from which a polymer is synthesized.
network polymer :A polymer produced from multifunctional monomers having three or more active covalent bonds, resulting in the formation of three-dimensional molecules.
repeat unit: The most fundamental structural unit in a polymer chain. A polymer molecule is composed of a large number of repeat units linked together.
thermoplastic polymer :A semicrystalline polymeric material that softens when heated and hardens upon cooling. While in the softened state, articles may be formed by molding or extrusion.
thermosetting polymer: A polymeric material that, once having been cured (or hardened) by a chemical reaction, will not soften or melt when subsequently heated.
Chapter 15 Polymer characteristics
elastomer : A polymeric material that may experience large and reversible elastic deformations.
glass transition temperature :The temperature at which, upon cooling, a noncrystalline ceramic or polymer transforms from a supercooled liquid into a rigid glass.
melting temperature : The temperature at which, upon heating, a solid (and crystalline) phase transforms into a liquid.
Vulcanization: A nonreversible chemical reaction involving sulfur or another suitable agent in which crosslinks are formed between molecular chains in rubber materials. The rubber's modulus of elasticity and strength are enhanced.