Characterization of the Microstructure of 50% Nickel - 50% Chromium Alloy Produced by Spray Metal Forming

摘要

In order to understand the microstructure of 50V0 nickel - 50% chromium alloy produced using spray forming, 3 mm diameter disks of the alloy were cut from several samples. The disks were thinned by electrochemical jet polishing using a mixture of HJP04 and H2S04. The microstructure is very complex. Some areas showed a composite structure of spherical 5- (Cr-Ni) particles imbedded in a dimpled matrix of Cr-Ni. Some areas had a distribution of spherical 8- (Cr-Ni) and Cr-Ni imbedded in planar nickel matrix. The most interesting result is that the microstructure consisted of areas of fine disc shaped (Ni3C, Cr2C and CrC) carbide precipitates dispersed in a nickel matrix. These carbides always tend to orient in a preferred direction, and formed a concentric ring type structure.