Primary carbide transformation in a high performance micro-alloy at 1000 °C

Research output: Contribution to journalArticlepeer-review

Authors

Colleges, School and Institutes

Abstract

The transformation from M7C3 → M23C6 in a high performance micro alloy (HP-MA) was studied using different techniques. Following the cooling during the centrifugal casting, the as-cast HP-MA alloy consists of an austenitic matrix with the primary carbide network consisting of a combination of M7C3 (M being mainly chromium) and MC (M being mainly niobium). During the heat treatment at 1000 °C, the primary chromium carbides transform from M7C3 to M23C6. The incompletely transformed primary carbide consists of an outer shell of M23C6 carbide (coherent with the austenitic matrix) and a core of M7C3 type carbide. The experimentally determined M23C6 shell thickness agrees reasonably well with the estimated diffusion distance of carbon in M23C6 based on Zener's relation implying that the M7C3 → M23C6 transformation is mainly controlled by the diffusion of the carbon from M7C3 to the matrix through the M23C6 shell. This mechanism is discussed vis-à-vis the literature reported mechanism on the transformation.

Details

Original languageEnglish
Pages (from-to)751-760
Number of pages10
JournalJournal of Alloys and Compounds
Volume781
Early online date7 Dec 2018
Publication statusPublished - 15 Apr 2019

Keywords

  • Carbide transformation, Diffusion, HP-Micro-alloys, Microstructure