# Effect of Ti-B Grain Refiners on Wear and Corrosion of the A332 Alloy with Sr Modification
## 3 Results
### Effect of Grain Refiner Addition on Wear Behavior  
Figure 10a-c shows the sliding wear track, after the ball-on-disk test using the Al2O3 sphere and load 3 N. Figure 10d-f shows the SEM and 3D profilometer images of the wear track after the ball-on-disk test. A plastic deformation can be seen in all conditions and the tendency of deep and shallow regions in circular-type formations. The wear track images showed in Figure 10a allow visualizing some debris accumulated during the testing by accumulation of aggregate aluminum particles in the sphere counterpart, which are detached during the test. Wear surfaces in Figure 10a-c show the wear grooves, with some plastic deformation and delamination characteristics. The samples with Al5 Ti2B grain refiner, observed in Figure 10b,e showed a different behavior with several subsequent circular deep shapes. Other samples showed worn tracks with some furrows typical of the abrasive-type wear mechanism visualized in Figure 10f. Adhesion and metal oxides are evident in Figure 10b.c. It seems that adhesion and delamination are the dominant mechanisms, preferentially in the Al5 Ti2B condition. From the 3D profiles obtained by OP shown in Figure 10d-f, deeper and shallow formations can be seen in all conditions. This situation is observed in the 2D surface profile in deep regions in Figure 11a and shallow regions (b) from respective localizations (I) and (II) in Figure 10d-f. The as-cast samples without grain refiner showed a deeper and wider worn track in both situations of samples wear track morphologies, with an average higher friction coefficient (\(\upmu\)) among all samples (Figure 12). Average friction coefficient (\(\upmu\)) was measured as an average of the values. The data were directly obtained from the test equipment. Although the condition with Al5 Ti2B showed changed wear track morphology, the surface profile is very similar with the samplesAl5 Ti2B (Figure 11). Figure 10: SEM images of wear track after the ball-on-disk testing from (**a**) as-cast; (**b**) Al5 Ti2B; (**c**) Al5 Ti2B 3D profiles obtained by OP images from (**d**) as-cast; (**e**) Al5 Ti2B; (**f**) Al5 Ti2B showing the spots of deep [I] and shallow regions [II] take in wear track from the 2D profile. The 3D profilometry analysis allowed calculating of the wear volume loss in each sample. With volumetric wear losses, relative wear resistance (\(\
abla_{\text{h}}\)) was calculated in accordance with Equation (2). The results are shown in Table 4.  
As-cast samples have the value of \(\
abla_{\text{h}}\) = 1 as they are from the same material, thus the reason is equal to one. The value was calculated from the volumetric loss standard \(\text{W}_{\text{hE}}\), by the volumetric loss of the reference sample \(\text{W}_{\text{hPV}}\). It is safe to assume that the volumetric loss of material reduces the wear resistance increase. Therefore, the values prove to be very close and there is no reason to believe any value is higher than other. Nevertheless, both results from the grain refiner's area are better than those of the as-cast condition. In order to better understand the wear behavior of the alloy, as explained by [PERSON] et al. [31], the relationship between wear conditions, hardness, and elastic modulus determined by nanoindentation was studied. \begin{table}
\begin{tabular}{c c c c} \hline
**Sample Material** & **As-Cast** & **Al5 Ti2B** & **Al5 Ti1B** \\ \hline Relative wear resistance & 1 & 1.359 & 1.353 \\ \hline \end{tabular}
\end{table} 
Table 4: Relative wear resistance. Figure 11: Comparison of 2D surface profile of A332 samples after wear test in (**a**) deep regions; (**b**) shallow of the wear tracks. Figure 12: Friction coefficient in the ball-on-disk testing. The relationship is designated by \(\frac{\mathrm{H}^{3}}{\mathrm{E}_{\mathrm{r}}^{2}}\), where H is hardness and \(\mathrm{E}_{\mathrm{r}}\) is the reduced elastic modulus and is known to be inversely proportional to wear [32; 33; 34].