Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Comparison of long-term natural aging to artificial aging in Duralumin   The understanding of long-term aging of aeronautical materials, in particular
aluminium alloys used in the fuselage and structure of aircraft is of extreme
importance for airline fleets. In this work, a plate from an old aircraft
(Breguet) was retrieved and studied in terms of microstructure and mechanical
properties. A comparison was made between this naturally-aged alloy and a
modern alloy on which different artificial aging conditions were applied. The
old alloy exhibits a precipitation of $\theta$-Al2Cu at grain boundaries and of
$\Omega$-Al2Cu on dispersoids. This non-expected nanostructure for an alloy in
T4 state was attributed to the heat that the plate experienced during the
aircraft cycles. However, it is shown that this aging is reversible (after a
solution treatment). Moreover, the very long time of outdoors exposure seems to
have caused intergranular corrosion causing the early failure during tensile
tests on some of the specimens. The artificial aging (low temperature,
100{\textdegree}C for up to 10,000h) applied on the modern 2017A alloy did not
allow to reproduce the nanostructure of the old plate, meaning that isothermal
conditions for artificial aging might not be appropriate in this case.

30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc