alpha iron - a magnetic allotrope of iron; stable below 906 degrees centigrade

pearlite - a lamellar mixture of cementite and ferrite formed during the cooling of austenite; a micro-constituent of steel and cast iron

primary solid solution, solid solution - a homogeneous solid that can exist over a range of component chemicals; a constituent of alloys that is formed when atoms of an element are incorporated into the crystals of a metal