I dont think so. There are some techniques Ive found using vacumes though but i think that is just to force teh molten metal into the shape, for example in the counter gravity one which is detailed on the site I linked to.
Edit - seems I forgot to link to any in the above posts, so here it is:
Investment casting:
http://www.hitchiner.com/himco/Basics.html
Counter gravity -
http://www.hitchiner.com/himco/Advantage.html
Im looking for infomation on melting the metal inside the mould. I have not seen any information on that so far.. maybe steel doesnt transfer heat well enough and it wouldnt be econmical..
The reson copper gets oxygen bubbles (which can only be seen under microscope because they are small! - unless the mould is not made proeprly to allow air to escape) is because at high temperatures copper
oxidises much quicker. When it is molten, and poured, there is a high contact between all of the molten copper with air, and not just the edges like when your copper waterblocks oxidise. This would make sence to me anyway, if anyone knows a better reson for the bubbles I would like to know!
Edit - Pic attached of teh channels I started to dremel into the base. Ive had to stop because the niose was annoying my parents
At the deepest point my vernier(sp?) measures 0.98mm. the gap between the channels so far is 1.58mm wide. and the only channel I have done so far is about 1.5mm wide. Hopefully i should manage 6 or 7 channels in there, and maybe do a bit deeper than I have so far.