Fig. 2
From: Corrosion of aircraft heritage: a comparison between modern and historic Duralumin alloys
Isometric representation (optical micrographs in bright field, etching with Keller’s reagent) showing grain size and shape of samples from the P (a–d) and the B (e–f) wrecks, as well as from modern alloys 2024 (g–h) and 2017A (i). The rolling plane of plates PL0 (D1, D2) is on top of each isometric representation. Extrusion plane for stringers: PL0 (D1, D2). Transverse plane: PL1 (D1, D3)