Moessbauer spectrometry study of Fe-Ni-X alloys

Technical Report · Mon Nov 01 04:00:00 EST 1982

OSTI ID:6350199

Fultz, B T

The Moessbauer effect was used for obtaining microstructural and microchemical information about two-phase tempering of Fe-9Ni alloys. Moessbauer spectra from many high purity materials with known compositions and thermomechanical processings were obtained by a calibration program. Martensite solute concentration changes were then determined from Moessbauer spectra obtained after tempering. This thesis attempts to cover the fundamental background material underlying the use of the Moessbauer effect for chemical analysis of ternary Fe-9Ni-1X alloys. A picture of electronic effects around solute atoms is presented in order to justify a semi-phenomenological model of linear response of hyperfine magnetic field perturbations to magnetic moments. Some formal development of this model allowed estimates of hyperfine structure to be made for non-dilute binary and ternary alloys. The temperature-dependent effects of Ni solutes on the shapes of Moessbauer peaks from binary Fe-9Ni alloys are analyzed within this model. The effects of ternary X solutes on Moessbauer spectra of Fe-9Ni-X alloys are also successfully estimated. Sensitive difference spectrum procedures were eventually developed so that +-0.03% concentration changes of many ternary solutes in martensite could be measured. The austenite formed by a nucleation and growth mechanism. Ni, Mn, Cr, and Si were found to segregate to the austenite. The addition of ternary solutes to a Fe-9Ni matrix had substantial effects on the rate of austenite formation and its stability against the martensite transformation. The austenite phase boundary was found to move towards lower Ni concentrations as some ternary solutes segregated to the austenite. The relative diffusivity of Ni versus that of the other solutes was largely responsible for determining the balance of solute concentrations in the austenite.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6350199
• Report Number(s): LBL-13588; ON: DE83008397
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOY SYSTEMS
ALLOYS
AUSTENITE
CARBON ADDITIONS
CRYSTAL STRUCTURE
DIFFUSION
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
IRON 57
IRON ALLOYS
IRON ISOTOPES
ISOTOPES
MARTENSITE
MICROSTRUCTURE
MOESSBAUER EFFECT
NICKEL ALLOYS
NUCLEI
STABLE ISOTOPES
STRUCTURAL CHEMICAL ANALYSIS
TEMPERATURE EFFECTS
TERNARY ALLOY SYSTEMS