alloys Flashcards
what is bronze an alloy of?
Copper and tin
what is brass an alloy of?
Copper and zinc
how many carats is pure gold?
24
what is bronze used to make?
medals, decorative ornaments, statues
what is brass used to make?
water taps, door fittings
what is gold mixed with to make what and why?
mixed with zinc, copper and silver when making jewellery to harden the gold as pure gold is very soft
18 carat gold meaning
18 out of 24 parts are pure gold, 75% gold
describe what aluminium is used to make
-low density which is important in aircraft manufacture
-pure aluminium is too soft
-so alloyed with small amounts of other metals to make it stronger
issue with pure metals
regular structure makes them soft, often too soft for everyday use
alloy
a metal made by combining two or more metallic elements
how do alloys make metals harder?
the atoms are different sizes, distorting the regular arrangement
means a greater force is required for the layers to slide over each other
what alloys are often used instead of pure iron?
steels
how are steels made?
by adding small amounts of carbon, and other metals to the pure iron
low carbon steel
-0.1-0.3% carbon
-softer
-easily shaped
-car bodies
high carbon steel
-0.22-2.5% carbon
-strong
-inflexible
-brittle
-blades for cutting tools
-bridges
