Directional solidification and {delta}/{gamma} solid state transformation in Fe-3% Ni alloy

Journal Article · Wed Oct 01 04:00:00 EDT 1997 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(97)00086-4· OSTI ID:554109

Vandyoussefi, M; Kerr, H W; Kurz, W ^[1]

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1. Swiss Federal Inst. of Tech., Lausanne (Switzerland)

Directional growth experiments were carried out to study the solidification behavior of {delta}-Fe and the {delta}-{gamma} solid state transformation in Fe-Ni alloys containing about 3 at.% Ni. Depending on the growth conditions, the solid-liquid interface morphology ranged from planar to cellular. In the solid state transformation, {gamma} grew from {delta} phase as plate like cells with small tip radii at low growth rates but as wider cells with flat interface at a velocity of 30 {micro}m/s. Volume diffusion-controlled plane front and dendritic growth models were applied to both transformations. This was possible as the diffusion coefficient of Ni in the parent {delta} phase is much larger than that of forming {gamma} phase. Good agreement was obtained between theory and experimental observations. The flat-tipped cells in the solid state transformations at a velocity of 30 {micro}m/s showed little overall change in composition, similar to a massive transformation. This composition-invariant transformation is consistent with a plane front growing with solute partitioning at the limit of absolute stability.

• OSTI ID: 554109
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 10 Vol. 45; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AUSTENITE
CHEMICAL COMPOSITION
CRYSTAL-PHASE TRANSFORMATIONS
DENDRITES
DIFFUSION
FERRITE
INTERFACES
IRON BASE ALLOYS
LIQUIDS
MORPHOLOGY
NICKEL ALLOYS
SOLIDIFICATION