The invariant line and precipitate morphology in fcc-bcc systems

Journal Article · Thu Sep 01 00:00:00 EDT 1994 · Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States)

DOI:https://doi.org/10.1007/BF02649034· OSTI ID:6891292

Weatherly, G C; Zhang, W Z ^[1]

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1. McMaster Univ., Hamilton, Ontario (Canada). Dept. of Materials Science and Engineering

Second-phase precipitates in many face-centered cubic-body-centered cubic (fcc-bcc) systems (e.g., Ni-Cr, Cu-Cr, Fe-Cu, and [alpha]-[gamma] stainless steels) have a lath-shaped morphology, the long axis of the lath being an invariant line of the transformation. The invariant line direction and major (habit) facet plane of the product phase can be predicted by O-lattice (O-line) models. For N-W-, and K-S-oriented precipitates, the habit plane is shown to be an unrotated plane of the transformation. This contains a single set of dislocations lying parallel to the invariant line, with their Burgers vector in the habit plane. Structural ledge models for the habit-plane interface also are considered. For the range of lattice parameter ratios of interest in this study, structural ledge and O-line models can make almost identical predictions as to the optimum habit plane. A variety of elasticity calculations for the energy of fully constrained or fully relaxed precipitates is presented. These models are shown to have limited predictive capabilities. It is suggested that better atomic matching along or near to the invariant line direction might explain the preference for K-S-related precipitates in many systems.

• OSTI ID: 6891292
• Journal Information: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Vol. 25:9; ISSN 0360-2133
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHROMIUM ALLOYS
MICROSTRUCTURE
COPPER ALLOYS
IRON ALLOYS
NICKEL ALLOYS
STAINLESS STEELS
BCC LATTICES
CRYSTAL-PHASE TRANSFORMATIONS
CRYSTALLOGRAPHY
FCC LATTICES
MATHEMATICAL MODELS
MORPHOLOGY
ALLOYS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CUBIC LATTICES
HIGH ALLOY STEELS
IRON BASE ALLOYS
PHASE TRANSFORMATIONS
STEELS
360102* - Metals & Alloys- Structure & Phase Studies