Origins of Intercrystalline Corrosion

The dissolution potential of intermetallic compounds differs from that of aluminium (Table B.2.1). Intermetallic compounds can be 

Solid solution Dissolution potential (mV SCE) Intermetallic phase 

Intercrystalhne corrosion will develop when three conditions are simultaneously met  

For precipitation hardenable alloys, the size and distribution of intermetallic precipitates depends on the quenching and artihcial ageing conditions. The continuous precipitation of intermetalhcs at grain boundaries can thus be avoided. 

In aluminium alloys, two different situations may occur precipitation of an anodic phase, or precipitation of a cathodic phase. 

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