选择性腐蚀 （英文:Selective leaching、selective corrosion、dealloying、parting、demetalification），又称去合金化，是固溶合金特有的腐蚀现象，当处在腐蚀环境下时，一金属元素（通常为活性较高者）被优先溶除 。选择性腐蚀的机制能以微观的伽凡尼腐蚀（galvanic corrosion）加以解释。合金组成金属的腐蚀电势序（galvanic series）差距较大者，通常较容易发生选择性腐蚀，如黄铜的锌与铜。合金中的锌、铝、铁、钴、铬等较易受选择性腐蚀溶出。

Selective leaching, also called dealloying, demetalification, parting and selective corrosion, is a corrosion type in some solid solution alloys, when in suitable conditions a component of the alloys is preferentially leached from the material. The less noble metal is removed from the alloy by a microscopic-scale galvanic corrosion mechanism. The most susceptible alloys are the ones containing metals with high distance between each other in the galvanic series, e.g. copper and zinc in brass. The elements most typically undergoing selective removal are zinc, aluminium, iron, cobalt, chromium, and others.