B2 long-range order in mechanically alloyed Fe53.3-0.6xCo46.7-0.4xSnx (2 <= x <= 26) annealed at moderate temperatures

作者：Malaman B; Le Caer G^*; Costa B F O

来源：Journal of Materials Science, 2016, 51(12): 5775-5790.

DOI：10.1007/s10853-016-9879-6

Recent interest in Fe-Co-Sn alloys stems from Heusler alloys. A Co2FeSn Heusler alloy is found to be unstable relative to other phases from ab initio calculations. However, it may be synthesized by non-equilibrium techniques. The present work focuses similarly on metastable ordered phases in ternary Fe-Co-Sn alloys. First, disordered phases of Sn in near-equiatomic Fe-Co are prepared by high-energy ball-milling. As-milled powders are then annealed to possibly produce long-range ordered phases. As-milled powders, of overall composition Fe53.3-0.6x Co46.7-0.4x Sn (x) (2 a parts per thousand currency sign x a parts per thousand currency sign 34), consist of a single supersaturated bcc phase for x < similar to 15 at.%. For larger values of x, they are primarily composed of a bcc phase, whose tin content still increases up to similar to 26 at.%, and of extra phases, which include hexagonal (Fe,Co)(3)Sn-2. Neutron diffraction patterns and Sn-119 Mossbauer spectra prove that bcc phases of as-milled alloys order to CsCl (B2)-type structures for x a parts per thousand currency sign 26 when annealed at 673 K. In addition, Sn-119 Mossbauer spectra reveal that a Sn content of similar to 15 at.% marks the separation between domains with different short-range orders. From previous and present results, metastable B2 ordering of Sn-rich Co-Fe-Sn alloys is concluded to occur over a significant concentration range.

• 出版日期2016-6