can anyone refer me to any site or book where i would get the properties of materials at nano scale and how they change with the change in the grain size?
I wouldn't look towards a book, I would look more towards literature. A good start would be researching grain size strengthening effects noted by Hall and Petch (the Hall-Petch effect).
Chris Schuh from MIT has shown a bunch of recent work on the development of thermodynamically stable nanocrystalline nickel alloys. He's shown pretty conclusively the relationship between grain size and indentation hardness.