Atomic-size effect on the microstructural properties of Ni2FeGa

The microstructural properties of melt-spun ribbon of the ferromagnetic shape-memory Heusler alloy Ni2FeGa have been investigated by transmission electron microscopy. Two kinds of micromodulated structures, Fe-rich and Ga-rich, have been established. The Fe-rich micromodulated structure is formed by Fe atoms partially replacing Ga atoms on {3 5 0} planes in the L2(1) structure. The Ga-rich micromodulated structure concerns Ga atoms partially replacing Fe atoms on {3 + n, 5 + n, 0}(n >= 0) planes. The Fe-rich and Ga-rich micromodulated structures originate from spinodal decomposition of the Fe and Ga compositions, which is closely related to the difference of atomic sizes of Ni, Fe and Ga. Crown Copyright (C) 2010 Published by Elsevier Ltd. on behalf of Acta Materialia Inc. All rights reserved.