# Effect of Ti-B Grain Refiners on Wear and Corrosion of the A332 Alloy with Sr Modification
## 3 Results  
### Microstructure Characterization  
To begin the analysis, Figure 2 shows the optical images from the A332 alloy in as-cast condition without grain refiner(a), and using Al5 Ti2B (b) and Al5 Ti1B refiners (c). The as-cast condition shows that the morphology of elongated arms of dendrites, while the other samples have more equiaxed grains. This modification of the shape and size of the grains is the result of the effect of increasing the formation of solidification nuclei when the different refining alloys, with Ti and B (AlTiB) were added. Regardless of the type of refiner, all the samples showed a primary aluminum phase, the eutectic phase, refined by the Sr modifying effect [26], and the intermetallic Fe and Cu phases, with different morphology.  
332 alloy, the use of the Sr modification, and the high solidification rate inhibit formation of the Al\({}_{15}\)(FeMn)\({}_{3}\)Si\({}_{2}\) phase [29].  
Figure 4 also shows in a light grey form the Cu peak and in a dark grey form the Fe peaks, as well as other regions with Si peaks. The Cu peaks show the presence of the Al\({}_{2}\)Cu phase, a common structure present in the Al-Si-Cu alloys [30].  
In Figure 5, the SEM images show the all-samples cross-sections. These images are presented in order to allow the analysis of the influence of the type of refining on the formation of needles-like Al\({}_{5}\)FeSi intermetallic phases. A general observation shows that in Figure 5, the needles Al\({}_{5}\)FeSi phase was formed mainly in the eutectic zone, although some were also observed inside the primary aluminum phase.  
Figure 4: (**a**) Secondary electron image A332 with Al5 Ti1B; (**b**) corresponding EDS line scan showing the elements peaks of Al\({}_{2}\)Cu phase 200\(\times\).  
Figure 3: (**a**) A332 Secondary electron image of Chinese-script phase with; (**b**) corresponding EDS line scan showing the elements of this phase 200\(\times\) present in the sample without grain refiner.  
The volume fraction, thickness, and length (\(\upmu\)m) of the Al\({}_{5}\)FeSi was measured by the quantitative metallography using MEV. It was found that the grain refining process influenced the amount of Al\({}_{5}\)FeSi phase in the alloy. In this sense, despite the lack of significant differences, there is a slight tendency to increase the volumetric fraction of the Al\({}_{5}\)FeSi phase, which ranged from 3.6 \(\pm\) 1.45% in the cast alloy without refiner to 4.2 \(\pm\) 0.74% in the refined alloy with AlSTi1B. However, there were changes in the morphology of this phase, varying the thickness and length, as shown in Figure 6.  
Figure 6 shows the difference of the average values of the thickness and length of the Al\({}_{5}\)FeSi intermetallic phase, depending on the type of refiner used. An increase in the length of the needles of the intermetallic phase can be verified, however, thickness decreased when the different refiners were used.  
The length of the Al\({}_{5}\)FeSi phase increased from 77.1 \(\pm\) 2.4 \(\upmu\)m in the alloy in the as-cast without the refiner condition to 104.4 \(\pm\) 3.5 \(\upmu\)m when the AlSTi1B refiner was used. However, no significant differences in length were observed when the type of refiner was modified, with more B (2 wt.%) in the composition. In addition, the thickness of the Al\({}_{5}\)FeSi phase also proved influential, decreasing the thickness from 4.02 \(\pm\) 0.18 \(\upmu\)m to 2.67 \(\pm\) 0.07 \(\upmu\)m, with the addition of the AlSTi2B refining type.  
Figure 5: Cross section of SEM images (**a**) cast condition without grain refiner; (**b**) grain refiner AlSTi2B; (**c**) grain refiner AlSTi1B—200\(\times\).  
Figure 6: Length and thickness of the intermetallic beta iron (Al\({}_{5}\)FeSi).