**5.1 Analysis of low Al-low indium alloys**

Results of experimental work on 88Sn▬7.5Zn▬2.5Al▬2In and 88Sn▬7Zn▬2Al▬2.5 in lead-free soldering alloys are presented below.

Microstructures taken at different locations in the prepared solders showed variations, and the detailed analysis of the microstructures is given below.

**Figure 1** shows the microstructure, and **Figure 2** shows the corresponding EDAX line spectrum. The weight % of sigma phase is 0.6%, when we consider the aluminium peak and 1.55% in the zinc peak. The indium cluster is seen in the middle and this showed 0.23% sigma phase. Sigma phase is a hard, brittle phase and generally not desirable. The presence of indium seems to have decreased the amount of sigma phase.

Indium peaks are not seen in **Figures 3** and **4**, when EDAX image is considered, and sigma phase is around 0.93% in both the Zn peak(first from the left) and the aluminium peak(second from the left). Sigma phase % age is more in this case compared to the previous microstructure (**Figures 5** and **6**).

**Figure 1.** *Spectrum 1 electron image.*

**Figure 2.** *Spectrum 1 EDAX graph.*

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**Figure 7.**

*Spectrum 10 electron image.*

*Role of Intermetallics in Lead-Free Alloys DOI: http://dx.doi.org/10.5772/intechopen.85515*

**Figure 4.**

**Figure 5.**

**Figure 6.**

*Spectrum 3 EDAX graph.*

*Spectrum 3 electron image.*

*Spectrum 2 EDAX graph.*

**Figure 3.** *Spectrum 2 electron image.*

*Role of Intermetallics in Lead-Free Alloys DOI: http://dx.doi.org/10.5772/intechopen.85515*

**Figure 4.** *Spectrum 2 EDAX graph.*

*Lead Free Solders*

**Figure 1.**

**Figure 2.**

*Spectrum 1 EDAX graph.*

*Spectrum 1 electron image.*

Microstructures taken at different locations in the prepared solders showed

**Figure 1** shows the microstructure, and **Figure 2** shows the corresponding EDAX line spectrum. The weight % of sigma phase is 0.6%, when we consider the aluminium peak and 1.55% in the zinc peak. The indium cluster is seen in the middle and this showed 0.23% sigma phase. Sigma phase is a hard, brittle phase and generally not desirable. The presence of indium seems to have decreased the amount of sigma phase. Indium peaks are not seen in **Figures 3** and **4**, when EDAX image is considered, and sigma phase is around 0.93% in both the Zn peak(first from the left) and the aluminium peak(second from the left). Sigma phase % age is more in this case

variations, and the detailed analysis of the microstructures is given below.

compared to the previous microstructure (**Figures 5** and **6**).

**14**

**Figure 3.**

*Spectrum 2 electron image.*

**Figure 5.** *Spectrum 3 electron image.*

**Figure 6.** *Spectrum 3 EDAX graph.*

**Figure 7.** *Spectrum 10 electron image.*

**Figure 8.** *Spectrum 10 EDAX graph.*

It is seen that 1.91% sigma phase is present in the Zn peak, whereas the indium peak, which occurs as two small peaks in the tin cluster, shows 0.20% sigma phase.

**Figures 7** and **8** show the microstructure and EDAX at another location. Here, sigma phase is 1.50% in the Zn peak and 0.55% in the aluminium peak. Indium peaks show 0.1% sigma and 1.425 sigma, respectively.
