Pure iron and aluminum powders were mixed in the equiatomic ratio and mechanically alloyed in a high-energy ball mill for different times. Structure refinement of x-ray powder diffraction data was performed to study the structural transformations induced by mechanical and subsequent thermal annealing treatments, The mechanical alloying (MA) process induces a progressive dissolution of aluminum phase into the bcc iron phase. After 32 h of MA a single-phase Fe(Al) bcc extended solid solution, with lattice parameter a(0)=2.891 Angstrom, average coherent domain size (D) approximate to 50 Angstrom, and lattice strain 0.5%, was observed. The annealing of the specimens after MA up to 8 h favored the aluminum dissolution in alpha-iron and the precipitation of the Al5Fe2 phase, whereas a nanostructured B2 FeAl intermetallic compound was observed in the annealed samples which were previously milled for 8, 16, and 32 h. In the same specimens a minority cubic phase Fe3AlCX, anti-isomorphous with perovskite, derived from contamination of ethanol and introduced in the steel vial as a lubricant agent, was also observed. Anelasticity measurements have shown the occurrence of two main transient effects during the first thermal run. The first one occurring at 500 K in all mechanically alloyed specimens was attributed to thermally activated structural transformations, whereas the second at about 700 K was attributed to a magnetic order-disorder transition. During the second run of anelasticity measurements a relaxation peak P-1 in the nanostructured B2 FeAl intermetallic compound, attributed to grain-boundary sliding mechanisms and with an activation energy of 1.8+/-0.2 eV was observed. In specimens milled for 8-32 h a second small peak P-2 at the low-temperature tail of the P-1 peak was observed and tentatively attributed to a Zener-type relaxation. (C) 1996 American Institute of Physics.

Structural and elastic behavior of Fe50Al50 nanocrystalline alloys / Bonetti, E; Scipione, G; Frattini, R; Enzo, Stefano; Schiffini, L.. - In: JOURNAL OF APPLIED PHYSICS. - ISSN 0021-8979. - 79:10(1996), pp. 7537-7544. [10.1063/1.362408]

Structural and elastic behavior of Fe50Al50 nanocrystalline alloys

ENZO, Stefano;
1996-01-01

Abstract

Pure iron and aluminum powders were mixed in the equiatomic ratio and mechanically alloyed in a high-energy ball mill for different times. Structure refinement of x-ray powder diffraction data was performed to study the structural transformations induced by mechanical and subsequent thermal annealing treatments, The mechanical alloying (MA) process induces a progressive dissolution of aluminum phase into the bcc iron phase. After 32 h of MA a single-phase Fe(Al) bcc extended solid solution, with lattice parameter a(0)=2.891 Angstrom, average coherent domain size (D) approximate to 50 Angstrom, and lattice strain 0.5%, was observed. The annealing of the specimens after MA up to 8 h favored the aluminum dissolution in alpha-iron and the precipitation of the Al5Fe2 phase, whereas a nanostructured B2 FeAl intermetallic compound was observed in the annealed samples which were previously milled for 8, 16, and 32 h. In the same specimens a minority cubic phase Fe3AlCX, anti-isomorphous with perovskite, derived from contamination of ethanol and introduced in the steel vial as a lubricant agent, was also observed. Anelasticity measurements have shown the occurrence of two main transient effects during the first thermal run. The first one occurring at 500 K in all mechanically alloyed specimens was attributed to thermally activated structural transformations, whereas the second at about 700 K was attributed to a magnetic order-disorder transition. During the second run of anelasticity measurements a relaxation peak P-1 in the nanostructured B2 FeAl intermetallic compound, attributed to grain-boundary sliding mechanisms and with an activation energy of 1.8+/-0.2 eV was observed. In specimens milled for 8-32 h a second small peak P-2 at the low-temperature tail of the P-1 peak was observed and tentatively attributed to a Zener-type relaxation. (C) 1996 American Institute of Physics.
1996
Structural and elastic behavior of Fe50Al50 nanocrystalline alloys / Bonetti, E; Scipione, G; Frattini, R; Enzo, Stefano; Schiffini, L.. - In: JOURNAL OF APPLIED PHYSICS. - ISSN 0021-8979. - 79:10(1996), pp. 7537-7544. [10.1063/1.362408]
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11388/46660
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 26
  • ???jsp.display-item.citation.isi??? 27
social impact