Precipitation in the iron--beryllium system

Journal Article · Fri Feb 01 04:00:00 EDT 1974 · Acta Met., v. 22, no. 2, pp. 201-217

DOI:https://doi.org/10.1016/0001-6160(74)90011-X· OSTI ID:4364056

Higgins, J; Nicholson, R B; Wilkes, P

Resu1ts are reported for an electron microscope study of precipitation in 12 and 18 at.% Be alloys. The reaction sequence is shown to be (at low temperatures): Spinodal decomposition- FeBe ordering of Be-rich regions - intermediate tetragonal precipitate in Be-rich regions - equilibrium FeBe/sub 2/. The spinodal reaction and ordering were separated by direct quenching experiments and the ordering process observed directly. Coarsening of the composition modulations followed a t1/2 law and gave an activation energy of 251 plus or minus 16 kJ/mole. The modulation solvus (spinodal) was found by these direct quenching experiments which also gave the ordering temperature. Direct quenching to temperatures above the spinodal caused nucleation of FeBe/sub 2/ which in turn led to the formation of intermediate precipitate in adjacent regions. This followed a nodular, branching mode until all regions had transformed. Further aging gave FeBe/sub 2. The solvas for the intermediate precipitate was found by direct quenching. The various precipitation regimes are summed up in a complete metastable phase diagram and the various products discussed in detail. (21 figres) (auth)

• Research Organization: Univ. of Manchester, Eng.
• Sponsoring Organization: USDOE
• NSA Number: NSA-29-013217
• OSTI ID: 4364056
• Journal Information: Acta Met., v. 22, no. 2, pp. 201-217, Journal Name: Acta Met., v. 22, no. 2, pp. 201-217; ISSN AMETA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

*BERYLLIUM ALLOYS-- PRECIPITATION
*IRON BASE ALLOYS-- PRECIPITATION
AGING
ELECTRON MICROSCOPY
N50230* --Metals
Ceramics
& Other Materials--Metals & Alloys--Properties
Structure & Phase Studies
PHASE DIAGRAMS
QUENCHING