B2 long-range order in mechanically alloyed Fe53.3−0.6x Co46.7−0.4x Sn x (2 ≤ x ≤ 26) annealed at moderate temperatures

Abstract

Recent interest in Fe-Co-Sn alloys stems from Heusler alloys. A Co 2 FeSnHeusler 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 Fe 53.3-0.6x Co 46.7-0.4x Sn x (2 B x B 34), consist of a single supersaturated bcc phase for x \ *15 at.%. For larger values of x, they are primarily composed of a bcc phase, whose tin content still increases up to *26 at.%, and of extra phases, which include hexagonal (Fe,Co) 3 Sn 2 . Neutron diffraction patterns and 119 Sn Mössbauer spectra prove that bcc phases of as-milled alloys order to CsCl (B2)-type structures for x B 26 when annealed at 673 K. In addition, 119 Sn Mö ssbauer spectra reveal that a Sn content of *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. temperatures below *1000 K for x ranging between *40 and *60 [1]. A perfect B2 FeCo alloy may be described as two interpenetrating simple cubic sublattices, in (0,0,0) and in (1/2,1/2,1/2), Fe on one and Co on the other. Ferromagnetism stabilizes the B2

Styrene Oxidation to Valuable Compounds over Nanosized FeCo-Based Catalysts: Effect of the Third Metal Addition

“…matches well with literature reports [24,25] It is also noted that the XRD patterns of the FCC series revel few diffraction peaks due to the low crystallinity of the samples, as depicted in Figure 3b. The peaks appearing at 2θ = 33.2° (110), 35.7° (002), and 39° (111) reflections are assigned to be from the monoclinic CuO structure (JCPDS 48-1548).…”

“…Based on the reflections at about 26. [24,25]. These types of alloys have a CsCl-type structure and result from the process related to the thermal antisite defects in Fe and Co vacancies, especially for FeCoSn-and FeCoCu-based materials [25].…”

“…[24,25]. These types of alloys have a CsCl-type structure and result from the process related to the thermal antisite defects in Fe and Co vacancies, especially for FeCoSn-and FeCoCu-based materials [25]. Moreover, the absence of Co 3 O 4 phase in all solids indicates that this phase experiences leaching during synthesis or that Co particles can be finely dispersed in a nanosized manner as a FeCo matrix.…”

“…One should note that the presence of segregated SnO 2 ,phases or phases containing Fe, e.g., Heusler alloys, is routinely encountered in studies of ternary FeCoMe systems (where Me indicates other metals) [25]. This is also explained by the relatively high temperature of ca.…”

Mechanosynthesis of bcc alloys from Fe50−y/2Co50−y/2Sn y mixtures (2 ≤ y ≤ 33) and B2 ordering by annealing at modest temperatures

“…We synthesized thus metastable ternary Fe-Co-Sn alloys by mechanical alloying (MA) of elemental powder mixtures, abbreviated as "p", of Fe, Co and Sn whose initial compositions (at.%) are denoted hereafter as p-Fe 50-y/2 Co 50-y/2 Sn y (2 ≤ y ≤ 33) [14][15][16][17].…”