PSI - Issue 72

Dragana Mihajlović et al. / Procedia Structural Integrity 72 (2025) 195 – 202

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3. Results and Discussion 3.1. Nanostructured oxide layer formed on the Ti-13Nb-13Zr surface

As can be seen in Fig. 2 nanostructured oxide layer, which consists of the nanotubes, is obtained after anodic oxidation process. Surface morphology shows the radius of nanotubes are ranging from 46 nm to 85 nm. In obtained morphology differences in the values of radius are pronounced which indicated that inhomogeneity of the nanostructured surface existed Barjaktarevi ć et al. (2019) . More about surface modification of the Ti-13Nb-13Zr alloy and morphology of the obtained nanostructured oxide layer can be read in our previous papers, Barjaktarevi ć et al. (2019), Barjaktarević et al. (2016), BArjaktarević et al. (2018), Barjaktarević et al. (2021) .

Fig. 2. Nanostructured oxide layer formed on the Ti-13Nb-13Zr alloy after anodic oxidation [7]

3.2. Experimental determination and analysis of the tensile behaviour of the Ti-13Nb-13Zr alloy after anodic oxidation The values of tensile properties (modulus of elasticity E , tensile strength R m and yield strength R p 0.2 ) of the Ti 13Nb-13Zr alloy before and after anodic oxidation are obtained after tensile testing done on the servo-hydraulic machine Instron 1255 . The anodic oxidation process leads to reduction of the values of R m , R p 0.2 . The value of R m of Ti-13Nb-13Zr alloy is reduced from 757.97 MPa to 611.77 MPa, while the value of R p 0.2 is reduced from 618.77 to 499.63 MPa , Barjaktarević et al. (2021) . Similarly, the anodic oxidation process leads to reduction in the value of E. Namely, the value of E of Ti-13Nb-13Zr alloy is reduced from 79.11 GPa to 63.21 GPa, Barjak tarević et al. (2021) . Fig. 3 presents behaviour of the Ti-13Nb-13Zr alloy during the tensile testing which was showed using Aramis system. Fig. 3a presents MTS Ti-13Nb-13Zr alloy at the beginning of tensile test. Fig. 3b presents strain at the F of 1.211 kN, while dl is 0.716 mm (moment of creation of the neck on the MTS), presence of the neck on the MTS indicates the existence of a ductile fracture, which is arises at the F of 0.825 kN when dl is 1.08 mm, Fig. 3c. Fig. 3d presents MTS of Ti -13Nb-13Zr alloy after tensile test. (all presented diagram and picture are Ti-13Nb-13Zr alloy before anodic oxidation).