Pulse Plating of Chromium‐Cobalt Alloys Containing a Phase with the A‐15 Structure

Abstract

Deposits of chromium‐cobalt alloys have been prepared by pulsed potentiostatic signals from a solution based on chromic acid. By changing two parameters of the electrolysis (off time and amplitude), alloys of various cobalt content with a thickness of about 10–25 μm were obtained. X‐ray diffraction measurements revealed that deposits of rich chromium content (up to about 75 w/o chromium) consisted of the A‐15 phase along with the α‐Cr (bcc) phase. Measurements indicated that the bcc lattice parameter decreases continuously with the increase of the cobalt content of the alloy. Alloys of about 33 w/o cobalt contained the σ intermediate phase together with the bcc and the A‐15 phases. Alloys with much higher cobalt were usually powdery and consisted mostly of the σ phase. X‐ray diffraction patterns of the chromium as‐plated deposits showed a strong preferred orientation of the A‐15 structure along the <100> direction.