Transformation strains in martensitic phase transitions of Co alloys |
| |
| Authors: | T Waitz H P Karnthaler |
| |
| Institution: | 1. Institut für Materialphysik, University of Vienna , Boltzmanngasse 5, A-1090, Vienna, Austria;2. Phone: + + 43-1-31367-3231 Fax: + + 43-1-31367-3231 E-mail: waitz@merlin.pap.univie.ac.at;3. Institut für Materialphysik, University of Vienna , Boltzmanngasse 5, A-1090, Vienna, Austria |
| |
| Abstract: | The thermally induced fcc → dhcp martensitic phase transformation was investigated in two different CoFe alloys (Co-5.75 and 6.0at.% Fe). Analysis by transmission electron microscopy methods yields that in both alloys the transformation proceeds by the movement of transformation dislocations (partials) that are correlated on an atomic scale; partials on adjacent close packed planes interact and combine to a paired partial. Two different and competitive modes of the transformation were observed. In Co-6.0 at. % Fe all the paired partials have the same Shockley partial Burgers vector adding up their long-range strain fields (transformation mode A). Contrary to this, in Co-5.75 at.%Fe paired partials of different Burgers vectors are compensating their long-range strain fields on an atomic scale (transformation mode B). The mode of the transformation seems to depend on both the parameters of the material and the experimental conditions. |
| |
| Keywords: | Martensitic phase transformation CoFe alloys Interfaces Transformation dislocations |
|
|
