**2. Microstructural examination**

A typical dendritic structure was observed in the as-cast substrate of Cu-10Sn bronze alloy as shown in **Figure 5** and the microstructure of the Ni surface alloyed Cu-10Sn alloy is shown in **Figure 6**.

It can be observed from **Figure 6** that the structure is very fine as opposed to a coarse structure observed in **Figure 5** and therefore it can be concluded that the grain refinement occurs as a result of the surface alloying process [3]. This refinement is due to the fast cooling experienced during solidification in the surface alloying process. A similar fine grained microstructure was observed for all the other Ni alloyed specimens also. Yilbas et al. [4, 5] studied the effect of laser surface modification treatment of aluminum bronze (Cu-9%Al-3%Fe) with

**Figure 5.** *As-cast Cu-Sn.*

**83**

**Figure 7.**

*Ni concentration measurement points.*

*Development of Functionally Gradient Cu-Sn-Ni Alloy Using GTA Heat Source*

B4C and reported that fine grains are formed at the laser treated surface in the surface modification process because of high cooling rate. Kac et al. [6] studied the structure and properties of surface alloyed aluminum bronze (Cu-10%Al-4%Fe-2%Mn) with Ti as the alloying element using laser heat source. They reported that a very fine microstructure was formed in the rapid solidification experienced in the laser process. Viswanadham et al. [7] studied the injection of TiC particles into aluminum bronze (Cu-7%Al-3%Fe-1.5%Mn) using the laser as the heat source. They have reported that the modified layer in the laser treated specimen was found to be dense and highly uniform when compared to the untreated specimen. Majumdar and Manna [8] carried out the surface alloying of pure Cu with Cr using the laser as the heat source and they have evaluated the microstructure resulting from the surface alloying process. They reported that the microstructure of the alloyed zone changed from coarse dendritic for the substrate to a fine dendritic structure in the surface alloying process. It can be concluded that the result obtained in the present study is consistent with that of

The Ni concentration on the surface of the modified layer formed in the surface alloying process was measured using the EDAX analysis. The concentration along the depth of the modified layer was also measured. **Figure 7** shows the points where the Ni concentration was measured. The Ni peaks can be observed in the EDS spectrum for all the surface alloyed specimen and the spectrum for 200 μm Ni is

Further, the results obtained by the EDAX analysis are reported in **Table 2**. The Ni concentration values (wt %) reported in **Table 2** are plotted against the distance along the depth of the modified layer. **Figure 9** shows the Ni profiles for

It can be observed from **Figure 9** that the Ni concentration is found to be the maximum on the surface of the modified layer for all the coating thickness. The Ni concentration decreases along the depth of the modified layer for all the coating thickness. It can be clearly observed that a gradient exists in the Ni concentration

*DOI: http://dx.doi.org/10.5772/intechopen.86315*

the previous studies.

shown in **Figure 8**.

profile.

various coating thickness.

**3. Ni concentration profile**

**Figure 6.** *Ni surface alloyed Cu-Sn.*

*Development of Functionally Gradient Cu-Sn-Ni Alloy Using GTA Heat Source DOI: http://dx.doi.org/10.5772/intechopen.86315*

B4C and reported that fine grains are formed at the laser treated surface in the surface modification process because of high cooling rate. Kac et al. [6] studied the structure and properties of surface alloyed aluminum bronze (Cu-10%Al-4%Fe-2%Mn) with Ti as the alloying element using laser heat source. They reported that a very fine microstructure was formed in the rapid solidification experienced in the laser process. Viswanadham et al. [7] studied the injection of TiC particles into aluminum bronze (Cu-7%Al-3%Fe-1.5%Mn) using the laser as the heat source. They have reported that the modified layer in the laser treated specimen was found to be dense and highly uniform when compared to the untreated specimen. Majumdar and Manna [8] carried out the surface alloying of pure Cu with Cr using the laser as the heat source and they have evaluated the microstructure resulting from the surface alloying process. They reported that the microstructure of the alloyed zone changed from coarse dendritic for the substrate to a fine dendritic structure in the surface alloying process. It can be concluded that the result obtained in the present study is consistent with that of the previous studies.
