Homogeneous martensitic nucleation in Fe-Co precipitates formed in a Cu matrix

Journal Article · Fri Jan 01 00:00:00 EST 1993 · Acta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-7151(93)90356-W· OSTI ID:6471516

Lin, M ^[1]; Olson, G B ^[2]; Cohen, M ^[3]

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1. Bethlehem Steel Corp., PA (United States)
2. Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering
3. Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering

The martensitic transformation on subambient cooling has been monitored in defect-free nanocrystalline f.c.c. Fe-Co particles that have been coherently precipitated in a Cu matrix; such a Cu-Fe-Co system was chosen for study because the f.c.c. [r arrow] b.c.c. transformational driving force in Fe-Co alloys is exceptionally large. Transformation is found to occur at a driving force of [approximately]10kJ/mol, a factor of 7 higher than the known critical driving forces for heterogeneous nucleation in bulk alloys. The observed transformation characteristics are entirely consistent with classical homogeneous coherent nucleation, whereas heterogeneous nucleation and homogeneous semicoherent nucleation can be ruled out in this case. An observed variation in transformation temperatures is explained by the experimentally determined differences in Co content (and, hence, in transformational driving force) among the Fe-Co precipitates in relation to their distribution of particle sizes. The role of thermal activation in the homogeneous nucleation process is demonstrated by applying a high magnetic field to impose an increment of driving force at low temperatures.

• OSTI ID: 6471516
• Journal Information: Acta Metallurgica et Materialia; (United States), Vol. 41:1; ISSN 0956-7151
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COBALT ALLOYS
CRYSTAL-PHASE TRANSFORMATIONS
COPPER BASE ALLOYS
IRON ALLOYS
BCC LATTICES
ELECTRON MICROSCOPY
EXPERIMENTAL DATA
FCC LATTICES
MAGNETIC FIELDS
NUCLEATION
TERNARY ALLOY SYSTEMS
ALLOY SYSTEMS
ALLOYS
COPPER ALLOYS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CUBIC LATTICES
DATA
INFORMATION
MICROSCOPY
NUMERICAL DATA
PHASE TRANSFORMATIONS
360102* - Metals & Alloys- Structure & Phase Studies