PROBIEN   20416
INSTITUTO DE INVESTIGACION Y DESARROLLO EN INGENIERIA DE PROCESOS, BIOTECNOLOGIA Y ENERGIAS ALTERNATIVAS
Unidad Ejecutora - UE
artículos
Título:
Primordial hexagonal phase formation during the bcc dezincification of the
Autor/es:
A. BARUJ, M. GRANADA, P. ARNEODO LAROCHETTE, S. SOMMADOSSI, H.E. TROIANI
Revista:
JOURNAL OF ALLOYS AND COMPOUNDS
Referencias:
Año: 2009
ISSN:
0925-8388
Resumen:
Subjecting CuZn samples to annealing under dynamical vacuum produces the evaporation of Zn, a process
knownas dezincification. Here,we study the phase transitions related to dezincification of Cu48 at.%
Zn (bcc, Beta phase) single crystalline surfaces with residual stresses due to mechanical polishing. In order
to identify different steps in the dezincification process of these deformed samples we apply a combination
of in situ optical microscopy and transmission electron microscopy (TEM) observations. The former
allows us to control and stop the dezincification process at a specific stage of evolution while the latter
allows relating surface features with structure and composition changes. Due to dezincification, the formation
of an on average 4H hexagonal phase and the fcc equilibrium phase take place. TEM observations
showthat the bcc to 4H phase transformation occurs by a mechanism of nucleation and growth. In particular,
we show evidence of the mechanism of embryo formation for the first time. During the subsequent
growth process, the coalescence of transformed zones defines regions in the micron range which after
subsequent prolonged dezincification transform to the final fcc equilibrium structure. These experiments
provide an insight on the reason for the formation of the non-equilibrium hexagonal phase during the
dezincification of electropolished (non-deformed) samples. The new experimental results evidence the
heterogeneous character of the dezincification.
allows us to control and stop the dezincification process at a specific stage of evolution while the latter
allows relating surface features with structure and composition changes. Due to dezincification, the formation
of an on average 4H hexagonal phase and the fcc equilibrium phase take place. TEM observations
showthat the bcc to 4H phase transformation occurs by a mechanism of nucleation and growth. In particular,
we show evidence of the mechanism of embryo formation for the first time. During the subsequent
growth process, the coalescence of transformed zones defines regions in the micron range which after
subsequent prolonged dezincification transform to the final fcc equilibrium structure. These experiments
provide an insight on the reason for the formation of the non-equilibrium hexagonal phase during the
dezincification of electropolished (non-deformed) samples. The new experimental results evidence the
heterogeneous character of the dezincification.
in situ optical microscopy and transmission electron microscopy (TEM) observations. The former
allows us to control and stop the dezincification process at a specific stage of evolution while the latter
allows relating surface features with structure and composition changes. Due to dezincification, the formation
of an on average 4H hexagonal phase and the fcc equilibrium phase take place. TEM observations
showthat the bcc to 4H phase transformation occurs by a mechanism of nucleation and growth. In particular,
we show evidence of the mechanism of embryo formation for the first time. During the subsequent
growth process, the coalescence of transformed zones defines regions in the micron range which after
subsequent prolonged dezincification transform to the final fcc equilibrium structure. These experiments
provide an insight on the reason for the formation of the non-equilibrium hexagonal phase during the
dezincification of electropolished (non-deformed) samples. The new experimental results evidence the
heterogeneous character of the dezincification.