Manipulations
Bending a metal at room temp...
(both names)
Cold working
Work hardening
Why did the government change the composition of the penny?
**For bonus 100, what are the %s that make up the penny today?
To make production cost cheaper.
97.5% zinc, 2.5% copper
What happens at the Curie temperature?
Material loses its magnetism.
Change 5.39% to a decimal.
0.0539
What type of structure do metals have?
Crystalline
Name three ways to work-harden a metal
Hammering
Bending
Twisting
Etc.
Describe the differences between annealing, quenching, and tempering.
Annealing: slow cooling by air
Quenching: rapid cooling by water/oil
Tempering: slow reheating (end of flame)
What type of defect is steel? What type of defect makes up other alloys?
steel is interstitial, other is substitional
A metal is made of 35% tin, 63% lead, and 2% gold. How many grams of each metal are in a 84g piece of the metal?
29.4g tin
52.92g lead
1.68g gold
What is an alloy? Give an example.
Mixture/combination of metals.
60% lead, 40% tin.
What happens to dislocations as a metal...
gets bent?
gets heated?
bent-increase
heated-decrease
What is the eutectic point?
The temperature at which a mixture of two substances produces the lowest melting temperature
Describe what the bounce in the iron wire demo was caused from (be specific).
Solid state phase change
bcc to fcc on the way down
fcc to bcc on the way up
A 2.6g penny is made from 92% copper, 8% zinc. How much did it cost to produce this penny?
- copper: $0.009554/gram
- zinc: $0.003125/gram
$0.02 cents
$0.023503168
What is the difference between malleability and ductility?
Malleability is being bent without breaking.
Ductility is being drawn into a wire without breaking.
Draw a picture of the atoms of a metal after it has been hammered THEN bent.
Thin with dislocations
What did the heat treating steel lab (bobby pins versus paperclips) show us?
We saw that high carbon steel is more affected by heat treatments than low carbon steel.
We saw this with the quenched bobby pins (high carbon) breaking while the quenched paper clips (low carbon) did not break.
Describe how steel is produced.
take iron, heat it up to fcc, throw carbon into it, cool it down.
Which penny costs more to produce:
A: 2.9g penny, 85% zinc, 15% copper
B: 1.3g penny, 99% copper, 1% zinc
copper: $0.009554/gram
zinc: $0.003125/gram
A: $0.011859115
B: $0.012336623
Penny B!
What crystal unit cell are atoms in after quenching?
BCT
Describe what happened in the tin twinning lab (be specific to tin)
Work hardening tin while it twinned (noise from stress)
*must mention twinning noise
Describe the alloy spot lab. Describe what the alloys were made of and why they melted.
Lead and tin alloy spots. As you mix metals together, their melting points decrease until you hit eutectic point.
Why does steel act differently based on heat treatments and copper does not?
Steel is an alloy with varying amounts of carbon. Copper is an element.
The carbon is what makes steel experience differences.
A 67g metal consists of copper, zinc, and nickel. The metal contains 45g zinc, 3g copper, and the rest is nickel. What is the percentage of nickel that the metal contains?
28.4%
(28.35820896)
Describe what happened in the penny lab to make a silver and gold penny.
Regular penny got plated with zinc (silver).
The heat from the hot plate allowed the zinc and copper to mix, creating brass (gold).