That doesn't mean anything; put fire to an 1/8 inch thick piece of steel with the exact dimensions as a piece of aluminum of equivalent size (doesn't matter what size they BOTH are), then take off the flame and record the temps and see which one cools down faster. Aluminum will get cooler faster. What do most electric motors use for heatsinks? Aluminum. What are most stock heatsinks for processors made of? Aluminum. Does anyone make a steel heatsink that has half a brain? No.
Thanks,
-Mitchell