EMA exam 3

The mineral olivine is a solid solution of the silicate compounds forsterite and fayalite. How many chemical components are there in a sample of olivine?

2

Seawater, which covers the majority of the earth, is composed primarily of molecules of H2O and equal numbers of Na+ ions and Cl- ions. Suppose we have a thoroughly mixed solution at 25*C. How many components and how many phases are in such a system?

2 component, 1 phase

At a eutectic point on a binary temp-composition phase diagram, how many phases are present when the system is at equilibrium?

3

At what temperature in Celsius may borosilicate be annealed?

564

What occurs during annealing?

A specific microstructure may be produced, stresses may be relieved, ductility may be increased, toughness may be increased

Which of the following sequences correctly indicates the severity of quench order of the three quenching media form least sever to most sever?

Air; oil; water

Which of the following are the two primary constituents of clays?

Alumina and silica

What describes recrystallization?

Diffusion dependent with no change in phase composition

Match the transformation description below with a name of a transformation of this type: diffusion-dependent with changes in phase composition

Eutectoid Reaction

T/F Equilibrium structures are commonly achieved in solid systems

False (metastable)

Of these polymers, which would be best suited for use as ice cube trays?

Glass transition temp under 0

Match the transformation description below with a name of a transformation of this type: Diffusionless

Martensitic Transformation

For which type of metals is powder metallurgy particularly suited?

Metals having high melting temperatures

Name the two general stages that accompany a phase transformation

Nucleation and Growth

T/F: When the concentration of solute in a solid solution exceeds its solubility limit, a new solution or phase forms that has a composition distinctly different than the original solid solution

True

A solidus line separates which of the following phase fields?

a and Liquid+a

For many technologically important metal alloys, the usual state or microstructure is:

a metastable one

A binary composition-temperature phase diagram for an isomorphous system is composed of regions that contain which of the following phases?

a, liquid, liquid + a

During thermal tempering, a glass piece is heated to a temperature

above the glass transition temperature, below the softening point

Which of the following polyethylene thin films would have the better mechanical characteristics

formed by extrusion and then rolled

Amorphous thermoplastics are formed above their

glass transition temperatures

A peritectic reaction involves which of the following combos of phase fields?

one liquid, two solids

Once a system is at a state of equilibrium, a shift from equilibrium may result by alteration of which of the following?

Pressure, composition, temperature

For a solution, which of the following is present in the higher concentration? Solute Solvent

Solvent