  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.
