The off-stoichiometric Ni-Mn-In heusler alloy undergo martensitic transition under the influence of varying temperature or magnetic field. I am having problem to identify the low temperature martensite phase in my Ni-Mn-In alloy. The XRD measurement even shows presence of a secondary phase (presumably a mrtensite) in L21 austensite matrix at room temperature. I am trying to do the Rietveld analysis of the XRD data but have not yet been able to identify the martensite. Can you please suggest a reference where a detailed structural information like atomic positions, space group etc. for martensite phases in Heusler alloys is given. Some references suggest an orthorhombic phase with Pmma space group at RT but do not give detailed crystallographic data.
Is it a thin film or a bulk sample? Is it as cast sample or you did some heattreatment? Did you obtain a DSC scan of your sample?
What are the transition temperatures? How was the alloy cast? At what temperature XRD was performed?
I work previously with Ni-Sn-Ti system and we determined Heusler and Halh_Heusler alloys by Scanning electrom microskope. About martensitic transformation I do not know, because I investigated system and alloys for high temperature solders.
I think the best way to identify the presence of martensite is DSC and supported by XRD
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