Parting, or Dealloying, Corrosion

Parting, or Dealloying, Corrosion This type of corrosion occurs when only one component of an alloy is removed by corrosion. The most common type is dezincification of brass. 

Oxidation has been known since Sir Humphrey Davy electrolytically decomposed potash in 1806 and dissolution as a form of corrosion was investigated by the British Navy in 1823 to develop a method preventing the degradation of their copper-huUed ships. Dealloying has been known by other names snch as leaching, dezincification or parting, graphitization, and so on which refer to the removal of a reactive metal component from an alloy or the purification of a noble metal from an alloy, respectively. 

When one element of a solid alloy is removed by corrosion, the process is known as selective leaching, dealloying, or dezincification. The most common example is the removal of zinc from brass alloys that contain more than 15% zinc. When the zinc corrodes preferentially, a porous residue of copper and corrosion products remains. The corroded part often retains its original shape and may appear undamaged except for surface tarrush. However, its tensile strength, and particularly its ductility, are seriously reduced. 

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