International Journal of Advanced Mechanical Engineering. ISSN 2250-3234 Volume 4, Number 6 (2014), pp. 639-646 © Research India Publications http://www.ripublication.com Modification of Al-11.1Si Alloy with Antimony through Casting Route Mohd. Suhail Ansari 1 , Deepak Sharma 2 , Vikram Tomar 3 Vikram Jaglan 4 1 Student at Department Of Material Science and Nano Technology University Of Petroleum and Energy Studies Dehradun, Uttrakhand. 2 Department Of Material Science and Nano Technology, University Of Petroleum and Energy Studies. Dehradun, Uttrakhand. 3 Student at Department Of Material Science and Nano Technology, University Of Petroleum and Energy Studies. Dehradun, Uttrakhand. 4 Student at Department Of Material Science and Nano Technology, University Of Petroleum and Energy Studies. Dehradun, Uttrakhand. 1.Abstract Aluminium silicon alloys is used in auto mobile (pistons, cylinder heads, brake disks etc) components because it shows high specific strength, low thermal expansion, high strength at elevated temperature, excellent castability, high corrosion resistance and wear resistance. The aim of the present work is to enhance the mechanical property of Al-Si alloy by changing the needle structure by chemical modification through casting process. These have been done by using pure antimony (Sb) as modifier with different composition 0.2, 0.3 and 0.4 wt% respectively and holding time 10, 15 and 20 minutes on Al- 11.1 Si alloy. Modification has occurred in most cases but in some case it is not up to the mark because in all cases the microstructure has shown the fine fibrous eutectic particle which is uniformly distributed throughout the sample and the size of α-Al grains are also reduced. Modified alloy is showing increase in density, hardness, elongation and ultimate tensile strength. Key words: Al-Si alloy, modification, modifiers, mechanical properties. 2. INTRODUCTION: Aluminium silicon alloys is used in automobile (pistons, cylinder heads, brake disks etc) components because it shows high specific strength, low thermal expansion, high strength at elevated temperature, excellent castability, high corrosion resistance and wear resistance. It is also used in structural application, marine application, military applications etc.[1-2] Instead of their widespread applications, their use in industry