1. Copper Wire Demo

2. Step 1: Bend the wire & try to straighten it
Observation: Takes more strength to try to bend it
Step 2: Hammer one end of the wire & try to bend it
Observation: Becomes harder to bend
WHY?
YOU INCREASE THE NUMBER OF DISLOCATIONS WHEN “WORKING THE METAL”.
DISLOCATIONS GET “PINNED”, THIS STRENGTHENS THE METAL, BUT MAKES IT MORE BRITTLE
Step 3: Heat hammered end until red hot
Observation: It’s softer, easier to bend
THE HEAT SOFTENED THE METAL & ALLOWED CRYSTALS TO RE-GROW
THE NUMBER OF DISLOCATIONS WERE DECREASED & MADE BIGGER CRYSTALS WITH FEWER GRAIN BOUNDARIES

3. How to use a Bunsen burner