PSI - Issue 33

Maria Beatrice Abrami et al. / Procedia Structural Integrity 33 (2021) 878–886 / Structural Integrity Procedia 00 (2019) 000–000

883

6

1.3. Damaging mechanism To identify the damaging mechanism of AlMgScZr alloy during wear and its evolution in time, SEM analyses were carried out both after 100 m and after 500 m of sliding distance. Fig. 5 displays SEM images after 100 m at the different testing temperatures, while Table 2 reports the corresponding EDS analysis. The formation of the oxide occurs in every test condition. In particular, at room temperature the oxide appears more granular with the presence of oxide particles, revealing greater oxide instability (Fig. 5 a-c). Instead, at higher temperatures, the oxide manifests itself as more compact scales or layers (Fig. 5 d-n). In these cases, oxide delamination and fracture with debris formation can be detected, together with the underlying AlScMgZr substrate in the areas where the oxide has already been removed (Fig. 5 f, I, m).

Fig. 5. SEM analysis of worn surfaces after 100 m of wearing tests at: (a-c) room temperature, (d-f) 100 °C, (g-i) 150 °C, (l-n) 200 °C.

Table 2. EDS analysis (wt. %) of areas indicated in Fig 4. Testing temperature Spectrum O Mg Al

Sc

1 2 3 4 5 6 7 8 9

27.97 29.95

2.76 2.60 3.52 3.59 2.13 2.81 2.77 3.76 4.03

69.26 67.45 94.74 95.16 53.38 62.64 71.73 96.24 95.20 82.29

- -

Room temperature

- -

1.74 1.26 0.68

100 °C

43.81 34.55

- - -

25.5

150 °C

- -

0.77 0.91

200 °C

10

13.11

3.7