Issue 49

M. J. Adinoyi et alii, Frattura ed Integrità Strutturale, 49 (2019) 487-506; DOI: 10.3221/IGF-ESIS.49.46

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Figure 3 : Optical metallographs of the AW2099-T83 alloy at different locations for transverse and extrusion directions.

R ESULTS AND D ISCUSSION

Microstructure ig. 3 shows the microstructure of AW2099-T83 in the various locations in the transverse (T1, T2, T3) and extrusion directions (E1, E2, E3) analyzed. The structure in the transverse orientation at location T1 is composed of clusters of small grains, measuring about 10 μm, intermingling with large grains of approximately 80 μm. The small grains resulted from recrystallization after solution heat treatment, while the large grains are unrecrystallized structures [21,24]. Comparable microstructures were reported for materials of similar type and were attributed to dynamic recovery and the presence of Al 3 Zr [31,32] . It is noted that grains become smaller towards the radius of the billet as can be seen in the micrographs representing T2 and T3 locations and these measure approximately 5-8 μm. However, in the direction of extrusion, elongated primary grains donated by α can be seen in the micrographs marked E1, E2 and E3 in Fig. 3. Within F

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