On the sheet with the bubble positions, find and label the following defect structures:

• vacancies
• grain boundaries
• interstitial atoms
• voids
• dislocation

How many close-packed directions are shown in the bubble raft model system? How do you locate them?
 
 
 
 
 

Along which directions are the dislocations located? Are all the dislocations oriented in the same direction?
 
 
 
 
 

When a stress was applied, did all the dislocations start moving at the same stress? Explain.
 
 
 
 
 

Would dislocation motion through an alloy be easier or harder compared to dislocation motion through the pure metal? What about a polycrystalline sample? Explain.