The precipitation process in a B2-TiNi-alloy has been studied during aging between 873-973 K for various aging times. Earlier reported results obtained with TEM/EDX-analyses showed the development of three different precipitates. The compositions, based on crystallographic calculations were found to be between 55-65 at % Ni. In the present study FIM/AP-analyses have been used to verify these compositional variations. At the early stages of precipitation only Ti3Ni4 is formed which could be analysed both by EDX as well as FIM/AP-analysis. The results of AP-analysis seem to be in better agreement with the calculated value of 57.1 at % Ni than the EDX results. The FIM images of the alloys show no crystallographic poles which is ascribed to the heavily twinned martensite transformation of the ordered B2-phase during cooling in the FIM. The Ti3Ni4-phase could be identified in the FIM images by the brightness and clear pole formation. The Ti2Ni3- and the Ti5Ni9-phase showed very brittle behaviour in the FIM, and AP-analyses showed better agreement with the calculated values than EDX, but can not be treated as conclusive yet.
|Journal||Journal de Physique|
|Publication status||Published - Nov 1988|
|Event||35th International Field Emission Symposium 1988 - Oak Ridge, United States|
Duration: 18 Jul 1988 → 22 Jul 1988
Conference number: 35