Correlation between Local Structure Distortions and Martensitic Transformation in Ni-Mn-In alloys

TL;DR

This study investigates how local structural distortions caused by varying Mn content influence martensitic transformation in Ni-Mn-In alloys, using EXAFS spectroscopy to analyze atomic-level changes.

Contribution

It reveals the correlation between local structural distortions and martensitic transformation, highlighting atomic volume as a key factor in Ni-Mn-In alloys.

Findings

Significant difference in Ni-In and Ni-Mn bond lengths in alloys with martensitic transformation

Atomic volume differences are linked to the onset of martensitic transformation

Local structural distortions are crucial in understanding phase change mechanisms

Abstract

The local structural distortions arising as a consequence of increasing Mn content in Ni_2Mn_1+xIn_1-x (x=0, 0.3, 0.4, 0.5 and 0.6) and its effect on martensitic transformation have been studied using Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy. Using the room temperature EXAFS at the Ni and Mn K-edges in the above compositions, the changes associated with respect to the local structure of these absorbing atoms are compared. It is seen that in the alloys exhibiting martensitic transformation ($x \ge 0.4$) there is a significant difference between the Ni-In and Ni-Mn bond lengths even in the austenitic phase indicating atomic volume to be the main factor in inducing martensitic transformation in Ni-Mn-In Heusler alloys.