ALPHA IRON • E-FREE TRANSLATION.COM • Definition of Alpha iron

... of the purest iron show at least two well-defined discontinuities at temperatures more than 1,000 deg.F., below its freezing-point. It seems that the soft, magnetic metal so familiar as wrought iron, and called "alpha iron" or "ferrite" by the metallurgist, becomes unstable at about 1,400 deg.F. and changes into the so-called "beta" modification, becoming suddenly harder, and losing its magnetism. This state in turn persists no higher than 1,706 deg.C., when a softer, non-magnetic "gamma" iron is the stable modification ...

— The Working of Steel - Annealing, Heat Treating and Hardening of Carbon and Alloy Steel • Fred H. Colvin