Assignment # 5 of Chemical and Materials Engineering

Define the following terms: a. Phase b. Component c. Eutectic d. Eutectoid e. Liquidus f. Solidus g. Solvus h. Microconstituent i. Phase constitution j. Lever rule k. System composition l. System temperature m. Isomorphous n. Phase diagram (Solution) a. Phase – A homogeneous portion of matter that has uniform physical & chemical characteristics. b. Component - Elements or compounds that are mixed. c. Eutectic - Literal meaning: Melting easily (in Greek). Eutectic reaction is a reaction wherein, upon cooling, a liquid phase transforms isothermally and reversibly into two intimately mixed solid phases. d. Eutectoid - Eutectoid reaction is a reaction wherein, upon cooling, one solid phase transforms isothermally and reversibly into two intimately mixed solid phases. e. Liquidus - A boundary separating liquid and liquid + solid regions on a phase diagram. The system is all liquid above this line. f. Solidus - A boundary on a phase diagram at which solidification is complete upon equilibrium cooling, or at which melting begins upon equilibrium heating. g. Solvus - Solvus line on a binary eutectic diagram separates a single phase solid from a dual phase solid region. h. Microconstituent - Element of the microstructure having an identifiable and characteristic structure. i. Phase Constitution – The phase constitution of an alloy is described by (a) the phase present (b) the (weight) fraction of each phase and (c) the composition of each phase. j. Lever Rule - Determination of phase amounts in two-phase co-existing region in a phase diagram. k. System composition – This is about how much of each element is present in total. l. System temperature – The temperature of our interest m. Isomorphous – Having the same crystal structure in the solid phase and complete solid solubility for all compositions. n. Phase diagram – A graphical representation of the phases present with variations in temperature and composition at equilibrium.