Abstract
Phase stability of chromium films plated from chromic acid electrolyte containing formic acid is studied by means of x‐ray diffraction and transmission electron microscopy. Five process parameters of electroplating are systematically varied and three different kinds of vacuum anneal are chosen in order to induce phase changes within the chromium films. Three phases are found: α, β, and amorphous phases. Their stability is strongly correlated with the hydrogen and carbon interstitials within the films, β‐phase is stabilized by hydrogen, while the amorphous phase is stabilized by carbon. When both interstitials are absent, then α‐phase is stable. During vacuum anneal, β‐phase decomposes into α or amorphous phase, while the amorphous phase remains metastable up to 500°C if carbon content is higher than 3 weight percent.