Time-dependent nature of displacive transformations in Fe–Ni and Fe–Ni–Mn alloys under magnetic field and hydrostatic pressure

Autor: Tomoyuki Kakeshita, J. Katsuyama, Toshio Saburi, Takashi Fukuda
Rok vydání: 2001
Předmět:
Zdroj: Materials Science and Engineering: A. 312:219-226
ISSN: 0921-5093
DOI: 10.1016/s0921-5093(00)01878-5
Popis: We have investigated athermal and isothermal martensitic transformations (typical displacive transformations) in Fe–Ni and Fe–Ni–Mn alloys under pulsed and static magnetic fields and hydrostatic pressures in order to understand the time-dependent nature of martensitic transformation, i.e. the kinetics of martensitic transformation. Following results were obtained, (i) in Fe–Ni alloys, which exhibit athermal martensitic transformations, isothermal holding at a temperature above respective M s temperature induces a martensitic transformation isothermally after some finite incubation time. (ii) In an Fe–32.6at.%Ni alloy, which originally does not show any athermal martensitic transformation, a martensitic transformation occurs isothermally after some finite incubation time. Moreover, in the alloy, a pulsed magnetic field induces an athermal martensitic transformation. (iii) A hydrostatic pressure changes the transformation process from athermal to isothermal one in Fe–31.7 and –32.3at.%Ni alloys. (iv) In an Fe–24.0Ni–4.0Mn (at.%) alloy, which exhibits an isothermal martensitic transformation, a static magnetic field lowers the nose temperature and reduces the incubation time and a hydrostatic pressure raises the nose temperature and increases the incubation time. These findings can be explained by the phenomenological theory, which gives a unified explanation for the two transformation processes previously proposed by our group.
Databáze: OpenAIRE
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