Formation of metastable bcc-δ phase and its transformation to fcc- in laser powder bed fusion of Fe-Mn-Si shape memory alloy

The phase transformation behavior from metastable bcc-8 to fcc-y in Fe-Mn-Si based shape memory alloy processed by laser powder bed fusion was investigated. Primary 8 phase formed in this alloy due to the rapid cooling and fast solidification. Bcc-8 to fcc-y phase transformation occurred when the volumetric energy density was high due to the process-inherent heat treatment effect. Transmission electron microscope studies confirmed Kurdjumov-Sachs orientation relationship between bcc-8 and fcc-y phases. The analytical results revealed that the phase transformation occurred by a combined displacive-diffusional mechanisms. (c) 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The phase transformation behavior from metastable bcc-8 to fcc-y in Fe-Mn-Si based shape memory alloy processed by laser powder bed fusion was investigated. The transformation occurred due to high volumetric energy density and was confirmed to be a combined displacive-diffusional mechanism through analytical studies. Transmission electron microscope studies also confirmed the Kurdjumov-Sachs orientation relationship between bcc-8 and fcc-y phases.