Question

Which of the following is/are true regarding internal corrosion?

(a) Corrosion products precipitate in the metal matrix

(b) Corrosion products precipitate in the metal matrix and metals such as Fe, Ni, and Co are highly prone to internal corrosion

(c) Corrosion occurs on external surfaces of metals

(d) It is due to the stable corrosion products of base metals

I had been asked this question in exam.

Origin of the question is High Temperature Materials topic in division High Temperature Corrosion of Corrosion Engineering

Answer 1

The correct option is (b) Corrosion products precipitate in the metal matrix and metals such as Fe, Ni, and Co are highly prone to internal corrosion

Easy explanation: Internal corrosion is due to the one or more dilute alloying elements form more stable oxides than the base metal and preferentially forms corrosion in the metal matrix. Iron, nickel, and cobalt are the base metals that are prone to internal corrosion.