Pre Exam

Which of the following correctly ranks the three types of ferrous alloys by their carbon content, from lowest (<0.008. wt% C) to highest (2.14 - 6.70 wt% C?

• iron, cast iron, steel

• steel, cast iron, iron

• cast iron, iron, steel

• iron, steel, cast iron

Select the choice that best completes the following sentence: When cooled slowly, transformations near the melting temperature tend to yield ___ grains due to the formation of___ nucleation sites followed by ____ grain growth.

• fine...few...slow

• coarse…few…slow

• coarse…few…rapid

• 
  fine...multiple..rapid

• fine…multiple...slow

  
  

In the Pb-Sn phase diagram, there are a number of invariant transformations and solid state phases. How many degrees of freedom are there in the solid alpha single phase region and at the invariant points. respectively?

• 
  2.0

• 0.2

• 1.0

• 1.2

For a solid-state transformation that obeys the Avrami equation, the parameter n has been determined to have a value of 1.5. The reaction takes 125 seconds to reach 30% completion. (What is the total time in seconds) for the transformation to reach 95% completion?

• 
  258

• 
  516

• 
  0.35

• 125

• 25

Based on the standard EMF series and your knowledge of half-reactions, determine the cell potential and spontaneity of a cell that consists of a pure cobalt electrode in a solution of Co2+ ions; the other half is a lead electrode immersed in a Pb2+ solution.

Pb2+  + 2e- —-> Pb    -0.126

Sn2+  + 2e- —-> Sn    -0.136

Ni2+   + 2e- —-> Ni     -0.25

Co2+  + 2e- —-> Co   -0.277

• +0.151, spontaneous

• -0.403, nonspontaneous

• -0.151, nonspontaneous

• +0.403, spontaneous

What best describes the thermodynamic condition that must be met for a state of equilibrium to exist?

• Maximized Gibbs Free Energy at constant temperature and pressure

• Metastability

• Minimized Entropy for a completely isolated system

• Minimized Free Energy

For the solidification of pure gold, calculate the critical radius (r*) and the activation of free energy (AG"). Assume homogeneous nucleation conditions. The values of the latent heat of fusion and the surface free energy are -1.16x10^9° J/m° and 0.132 J/m?, respectively. The degree of supercooling is 230 K and the meting point of gold is 1064 °C.

• 1.3 nm and 9.6x10-19 1/m^2

• 0.9 nm and 4.2x10-19 J/m^2

• 126 nm and 1.5×10-18 J/m2

• 0.6 nm and 2.3×10-19 J/m~2

• 10.1 nm and 5.7x10^-175/m^2

For the solidification of pure gold, calculate the critical radius (r*) and the activation of free energy (AG"). Assume homogeneous nucleation conditions. The values of the latent heat of fusion and the surface free energy are -1.16x10^9° J/m° and 0.132 J/m?, respectively. The degree of supercooling is 475 K and the meting point of gold is 1064 °C.

• 1.3 nm and 9.6x10-19 1/m^2

• 0.9 nm and 4.2x10-19 J/m^2

• 126 nm and 1.5×10-18 J/m2

• 0.6 nm and 2.3×10-19 J/m~2

• 10.1 nm and 5.7x10^-175/m^2

Corrosion of structural metals can occur in a variety of ways. Identify the appropriate type of corrosion for the following situation:

A form of intergranular corrosion which occurs in the heat affected zones of stainless steel welds through the formation of Cr23C, precipitates.

• Galvanic Corrosion

• Crevice Corrosion

• Selective Leaching

• Pitting

• Sensitization

There are several techniques available for suppressing and controlling corrosion. Which of the following would be most suitable from economic and engineering perspectives for protecting an underground storage tank?

• Institute cleaning and inspection regime

• Minimize temperature of tank

• O Coat with noble metal (i.e. gold)

• Cathodic protection