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.