THE STRUCTURE OF FE - CR ALLOYS

Structural changes in the urinary alloys Fe - 10, 20, 30, 40, and 47 w t.% Cr were investigated by electron microscopy and X-ray diffraction analysis. Depending on the composition, all as-quenched alloys (except Fe - 10% Cr) exhibit either the tweed or pointed structure, which is due to different types of chromium clusters. A Fe - 47% Cr alloy conta ins grains of the so-called sigma phase consisting of the alternating layers of almost pure iron and pure chromium. Aging leads to further d ecomposition of the as-quenched structure.