This creates a flow of electrons between the metals that eventually causes them to disintegrate. One way to prevent this corrosion is to replace one of the metal pieces with another that is compatible with the mating piece. For example, many aluminum storm doors have steel rivets holding the hinges or closing piston in place. Often, corrosion starts around these fasteners then works to the adjacent aluminum panels. Drilling the corroded fasteners out and replacing them with aluminum pop-rivets will stop the galvanic corrosion before it has a chance to spread.
Crevice corrosion occurs around the joints and seams of metal fixtures where dirt accumulates.
By itself the dirt is not particularly harmful, but it allows moisture to collect and this causes corrosion. Joint and seam corrosion is a common occurrence on gutters and downspouts. Clean them often to keep dirt and leaves, which retain moisture, from building up. Make sure that gutters are sloped toward the downspout to eliminate standing water. If rust is present, remove it with a flexible sanding wheel chucked in an electric drill, then prime and paint the bare metal.