Effect of atomic order on the phase transitions of melt-spun Ni50Mn35In15 ribbons.

The phase transitions of melt-spun Ni₅₀Mn₃₅In₁₅ ribbons are modulated with post-annealing. Both the martensitic transformation temperatures and Curie temperature of the austenitic phase increase after post-annealings. However, the maxima of phase transition temperatures are obtained after 873 K annealing, instead of higher-temperature annealings. The nonmonotonic dependences exclude Mn volatilization and grain growth from the dominant reason. The superlattice reflections in Heusler structure indicate that the increases of phase transition temperatures should be related to the increment of L2₁ atomic order. [ABSTRACT FROM AUTHOR]