1. Aluminum vs Cast Iron
Aluminum and iron are two very distinct types of metal, quite different from each other, that exhibit an
array of varying properties. One of the first differences that you’ll notice between the two would be the
significant discrepancy when it comes to their weight. Cast iron is certainly much heavier than
aluminum. Because of the fact that aluminum is so lightweight, it is often used in building all sorts of
machinery as well as automobiles. Now, shall we take a closer look at each type of metal?
Cast iron or grey iron, as it is sometimes referred to, is part of rather large group of alloys that turn solid
through a eutectic. One way of identifying which alloy you’re looking at is through the color of its
fractured surface. There is one type that’s referred to as a white cast iron because of the white surface
that shows when it is fractured. Grey cast iron, as the name suggests, has a grey fractured surface. As for
strength, cast iron does have a tendency to be brittle. The only exception would be malleable cast irons
which have a significantly lower melting point, castability, good fluidity, wear resistance, excellent
machinability and resistance to deformation. This is why this type of cast iron is often used as an
engineering material with a variety of different applications.
This includes the creation of automotive parts, pipes, various machines, cylinder blocks, cylinder heads
as well as gearbox cases despite the fact that its usage has significantly declined over the years.
Aluminum, on the other hand, is one of the most abundant metals found in the earth’s crust. As a
matter of fact, about 8% of the Earth’s solid surface is made up of aluminum. However, it is too
chemically reactive to occur as a free metal in nature. Instead, one would find it mixed in with about 270
different minerals which the chief source being bauxite ore. Besides being known for having a low
density, aluminum is also remarkable for being able to rests corrosion. Because of this, it has become a
vital component when it comes to creating many different things which are used in construction,
transportation and even aerospace. Another amazing bit about aluminum is the fact that it is among the
best thermal and electrical conductors. As a matter of fact, it has the capability of becoming a
superconductor.
Aluminum, unlike most other metals, is nonmagnetic as well as being nonsparking. Also, the stronger a
piece of aluminum gets, the less corrosion resistant it becomes. The same goes for when aqueous salts
are present.

2. Now that you have a pretty good idea as to the differences between the two, let’s talk about how you
can tell one from the other. As mentioned earlier, aluminum is nonmagnetic and as such, this is the first
test that you should do. A simple magnet or a compass needle would not be affected by a piece of
aluminum. However, this is the complete opposite in the case of cast iron as both would be attracted to
it. In terms of oxidation, cast iron tends to oxidize quicker when exposed to humid or damp air. It will
continue to oxidize if you leave it exposed to the elements. On the other hand, aluminum often would
become coated with an invisible layer of aluminum oxide which in turn protects it from oxidizing even
further. Do keep in mind that there are certain treatments that can be done to cast iron pieces to
prevent them from oxidizing easily. Remember to ask your supplier about it.
Summary:
Aluminum is lighter in density when compared to cast iron.
Aluminum is the most abundant metal found in the Earth’s surface.
Cast iron oxidizes faster than aluminum.
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