Microstructure Characterization of High Carbon Alloy from the Ni-Ta-Al-Co-Cr System / Charakterystyka Mikrostruktury Wysokowęglowego Stopu Z Układu Ni-Ta-Al-Co-Cr

Abstract

In the present work results of investigations of the new high carbon alloy from the Ni-Ta-Al-Co-Cr system are presented. The alloy has been designed to have a good tribological properties at elevated temperatures. The chemical composition of this material was designed to obtain a matrix strengthening by the precipitation of γ’ phase (Ni3(Al,Ta)) and the primary carbides volume fraction above 25%. The primary carbides should remain stable in the microstructure, regardless of the heat treatment, in order to increase a wear resistance. The results of microstructure investigations in the as-cast condition are presented. The type of phases appearing in the microstructure was determined and their morphology described. The main microstructure components of the investigated Ni-based alloy with high carbon, cobalt and chromium content are: the γ phase, which constitutes a matrix, the γ’ phase, which occurs as fine globular precipitates and the primary Ta and Cr carbides (of MC and M7C3 type - respectively).