Evidence of multi-layer GP zones in Al-1·7at.%,Cu alloy

Abstract

GP zones in A1-1·7at.%Cu alloy aged at room temperature for 760 h, and 373 and 403 K for less than 1000min, have been observed by field-ion microscopy to elucidate the structure of the zones. A typical zone structure was found to be the well-known single layer of Cu atoms on (001) planes. On the other hand, another type of zone, i.e. multi-layer GP zones, was found to co-exist with the single-layer GP zones. Detailed observation on (022) and (002) planes showed that the multilayer GP zones consist of a few Cu-rich layers on (002) planes.