| Autor: |
P.G. Winchell, G.R Speich |
| Rok vydání: |
1970 |
| Předmět: |
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| Zdroj: |
Acta Metallurgica. 18:53-62 |
| ISSN: |
0001-6160 |
| DOI: |
10.1016/0001-6160(70)90068-4 |
| Popis: |
Point defect sites in austenite and martensite may be characterized by the point at their center. Such points may be divided into sets of equipoints according to their point symmetry. These sets may be further divided into subsets according to the orientation of their principal symmetry axis. The Bain correspondence of such subsets of equipoints in austenite to analogous subsets of equipoints in martensite is presented. Certain subsets of equipoints can support tetragonality. From available data, we agree with current ideas that interstitial atom point defects (carbon or nitrogen) are very probably at octahedral sites and produce tetragonality by “hard ball” effects. We hypothesize that substitutional solutes A and B which form an A 3 B compound in iron in the austenite range may be expected to support tetragonality in substitutional iron-base martensite because these tetrahedral A 3 B molecules tend to retain their close-packed configuration in the martensite. This produces tetrahedral point defects in the martensite which act as local anisotropic strain centers and produce tetragonality. For such substitutionally supported tetragonality the r.m.s. static displacements are more nearly equal than for interstitial martensite. Also, a low-temperature internalfriction peak in such martensite now is expected. The recently reported tetragonality of Fe-Ni-Ti martensites is an example of this latter type of tetragonality. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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