Corrosion, rust, build up, nasty mess, but he most common is "corrosion", then "rust".
The most common type of corrosion found on aluminum and magnesium alloys is galvanic corrosion, which occurs when these metals come into contact with a more noble metal in the presence of an electrolyte. This causes accelerated corrosion of the aluminum or magnesium.
This is called a corrosion test, frequently used in quality control of materials.
i don't think there is another name for "corrosion", i mean there are different ways to define "corrosion". you can call it oxydation but is not the exact definition since is just a part of the process "corrosion". http://www.corrosionist.com/Corrosion_Fundamental.htm
Oxygen corrosion, also known as oxidation corrosion, is a process in which metal deteriorates due to exposure to oxygen in the environment. It is a common form of corrosion and can lead to structural weakening and eventual failure of the metal. Preventive measures such as protective coatings or using corrosion-resistant metals can help mitigate oxygen corrosion.
"Rusty" could be a good nickname for corrosion, as it is a common result of metal oxidation and decay.
Stainless steel, titanium, and gold are known for their resistance to corrosion. These materials form stable oxide layers on their surfaces, protecting them from environmental factors that cause corrosion.
Corrosion/rust.
Corrosion on trigger wire at starter
Rusting
An oxide
a common cause of this type problem is corrosion at a connector.
The most common problem I encounter is copper pipe corrosion. A close second is worn seats in taps.