Barriers to the Migration of Interphase Boundaries, Particularly in Steel.
Abstract
The growth kinetics of proeutectoid ferrite, in the form of grain boundary allotriomorphs, were measured vs. reaction temperature in Fe-C-X alloys where X was Si, Mn, Cr and Ni. Comparison of measured growth kinetics with those calculated often shows poor agreement with the local equilibrium model; order of magnitude agreement was obtained with both the pileup and the paraequilibrium models. A limiting alloying element penetration calculation, however, showed that only the paraequilibrium model is basically consistent with the experimental data. TEM studies showed that measured growth kinetics somewhat slower than those predicted by the paraequilibrium model are not due to carbide precipitation at austenite:ferrite boundaries. Such slower growth kinetics appear to be best explained by a solute drag-like effect. Carbide precipitation at austenite:ferrite boundaries in Fe-C-X alloys was shown to increase growth kinetics when X is Si, Ni and V. Incomplete transformation in Fe-C-Mo alloys was demonstrated to occur only when critical proportions of C and Mo are exceeded. Thermodynamics of the proeutectoid ferrite reaction in Fe-C alloys were reassessed using recent theory and thermodynamic data. Structural ledges were observed to occur reproducibly on planar facets formed during the beta yield alpha sub m Cu-Zn massive transformation. The misfit dislocation structure of the lamellar interfaces in the Co(Al)-CoAl eutectic was observed to be significantly affected by the presence of LRO in the CoAl phase. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 20, 1979
- Accession Number
- ADA080384
Entities
People
- H. I. Aaronson
- J. R. Bradley
- T. Abe
- T. Obara
- W. A. T. Clark
Organizations
- Michigan Technological University