Auto Parts: old cars, head gasket failure, cast iron engines

Question
Do you know in what year did auto makers made the switch from cast iron engines to aluminum engines?which company was first to do so and why?

Answer
    It's not all that simple.  There were aluminum engines being built in Europe back before WWI.  All of the aircraft engines in WWII were made of aluminum.  American manufacturers tended to stick with cast iron because it was cheaper for them; they already owned their own foundries and the production of aluminum as a raw material was very expensive back then.  It still is considerably more expensive than cast iron.  As far as American cars go, Buick built aluminum engines in the early sixties.  Faced with this competition the iron founders introduced new techniques for thin-wall casting of iron that weighed no more than the aluminum blocks.  The common use of aluminum in cylinder heads goes back to the fifties in Europe and the seventies in Japan.  I had a 94 Toyota which was the first year that they used aluminum in both the head and block.  The widespread use of aluminum today is due mostly to the differential expansion of the two metals.  Using iron in the bottom end and aluminum in the top end can result in head gasket failure, especially if the engine is overheated.