Figure 1: X-ray diffractograms of spray formed alloys

Figure 2: SEM/EDS of as cast alloy (a) Al-17Si and (b) Al-22Si

Figure 3: SEM/EDS of spray deposited alloys (a) Al-17Si and (b) Al-22Si

Figure 4: Optical microstructure of Al-22Si alloy (a) SD and (b) SD+HP

Figure 5: Tensile fracture surfaces of SD+HP alloys (a) Al-17Si and (b) Al-22Si

Figure 6: Tensile fracture surfaces of as cast alloys (a) Al-17Si and (b) Al-22Si

Alloy

Si

Fe

Mn

Mg

Cu

Ni

Al

Al-17%Si

17

0. 3

0.06

0.24

0.06

---

Bal

Al-22%Si

22

0. 4

0.02

0.14

0.06

--

Bal

Table 1:Nominal chemical composition (wt.%) Al-Si Alloy

Melt Superheat

250 ºC

Melt flow rate

2.5 kg/min

Gas pressure

0.65Mpa

Diameter of nozzle

4.0  mm

Deposition   distance

390mm

Table 2: Spray deposition process variables employed in present study

Location

Composition

Phase

Al-K

Mg-K

Si-K

Fe-K

Point 1

Al67Fe17Si164

Intermetallic

56.09

0.00

14.21

29.71

Point 2

Al99Si1

-Al Matrix

99.00

0.00

0.87

0.05

Point 3

Si98Al2

Si

1.45

0.0

98.54

0.00

Table 3: EDS analysis of spray deposited Al-17Si alloy

Location

Composition

Phase

Al-K

Mg-K

Si-K

Fe-K

Point 1

Al10Si88

---

11.22

0.05

88.30

0.00

Point 2

Al99Si1

-Al Matrix

96.59

0.00

2.75

0.25

Point 3

Si98Al2

Si

1.62

0.12

98.11

0.00

Table 4: Properties of Zinc Oxyde ZnO

Alloy

Density of
as cast alloy  (gcm-3)

Density of  SD alloy(gcm-3)

Density of SD+HP alloy (gcm-3)

Porosity of   SD alloy (%)

Porosity of      SD+HP   alloy (%)

Al-17Si

2.628

2.38 (90.0%)

2.51 (95.6%)

10.5

4.3

Al-22Si

2.60

2.43 (93.5%)

2.481 (95.4%)

9.6

5.5

Table 5: Properties of Aluminium Al

Alloy

Processing route

Phase

Hardness (Hv)

Improvement of hardness (%)

Al-17Si

As-cast

Eutectic

53 ±1.34

--

Al-22Si

As-cast

Eutectic

58 ±2.24

----

Al-17Si

SD+HP

Bulk

66.5 ±2.74

24.8

Al-22Si

SD+HP

Bulk

83 ±1.64

40.5

Table 6: Micro-hardness of as-cast and SD+HP Al-Si alloys

Alloy

Yield strength MPa)

UTS (MPa)

Elongation%

As-cast Al-17Si

49

53

2.2

As-cast Al-22Si

43

48

2.7

SD+HP Al-17Si

116

158

16

SD+HP Al-22Si

136

164

12

Table 7: Tensile properties of as-cast and SD+HP alloys