Relationship between the Crystallographic Structure of Electrodeposited Fe-Cr Alloy Film and Its Thermal Equilibrium Diagram

Abstract

The crystallographic structure and morphology of electrodeposited Fe-Cr films under different bath conditions were studied in detail by using XRD, HRTEM and SEM. The crystallographic structures of the Fe-Cr electrodeposits were also compared with the Fe-Cr thermal equilibrium diagram. The results indicated that the crystallographic structure of electrodeposited Fe-Cr alloy film gradually changed from microcrystalline to amorphous with increasing Cr content. The deposited film exists as α-Fe solid solution when the Cr compositions of deposited films are below 3.1 at%, whereas, it existed as a meta-stable crystal when the Cr compositions of deposited films are from 4.5 at% to 22.4 at%, which have not been reported up to now. The deposited films with various Cr compositions from 22.9 at% to 74.4 at% chromium exist as amorphous phase. Hence, the crystallographic structure of the electrodeposited Fe-Cr alloy film is closely related to its thermal equilibrium diagram, but does not always agree with it.

Relationship between the Crystallographic Structure of Electrodeposited Fe-P Alloy Film and its Thermal Equilibrium Phase Diagram

“…1) In general, the amorphous alloys can be prepared by several techniques, i.e., rapid solidification of the melting metal, dry process such as ion sputtering and ion implantation, and wet process such as electrodeposition [2][3][4][5] etc. The electrodeposition potentially offers an easy one-step technique to form monolithic parts out of amorphous alloys with appreciable thickness and controlled shape, and then has been extensively utilized in industry as an indispensable technique.…”

Production of Iron Alloy by Direct Electrolytic Reduction Using Suspension Electrolysis in an Alkaline Electrolyte

“…Fuseya and Sasaki 14 obtained Fe-Cr deposits with Cr compositions of 5.0-65 at % at 80-250 mA･cm −2 , with a current efficiency of less than 14% in a sulfate electrolyte. Wang and Watanabe 15,16 produced Fe-Cr deposits with Cr compositions of 3.1-74 at% at 50-250 mA･cm −2 from a chloride source, while Yagi et al 17,18 fabricated a Fe-Cr layer on a Fe substrate with a current efficiency of approximately 21% using sulfate sources. Although trivalent chromium ions were used in these studies, highly toxic hexavalent ions were generated therein by proportionation/disproportionation reactions.…”