which vessel is best to boil milk in - steel, hindalium or aluminium? and why?

Answer 1

Steel is a better conductor of heat (i.e., has a higher thermal conductivity) than aluminum, so steel pots will allow the contents to heat faster and more evenly (hindalium is a cast aluminum).

Answer 2

actually which ever has the higher conductivity is better to use. The higher the higher the thermal conductivity value, the more heat gets from the bottom of the vessel to the inner region of the vessel.
from the data table provided here it can be seen that steel has lower thermal conductivitythan steel. Check it out.
http://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html

Answer 3

I would use stainless steel, because aluminum is a toxic heavy metal. Some say it doesn't matter, but whenever we cooked our children's oatmeal in aluminum, their faces would flush (turn red) for half an hour after they ate. Needless to say, we no longer use aluminum cookware.