The crystallization process of the eutectic composition of GdAlO_3-Al_2O_3 from the amorphous phase prepared by rapid-quenching of melt that leads to the formation of a cantaloupe skin-like microstructure was investig...The crystallization process of the eutectic composition of GdAlO_3-Al_2O_3 from the amorphous phase prepared by rapid-quenching of melt that leads to the formation of a cantaloupe skin-like microstructure was investigated using focused ion-beam scanning electron microscopy (FIB-SEM) and high-resolution transmission electron microscopy (HR-TEM).The amorphous films were heat-treated at temperatures between 1000 °C and 1500 °C for up to 30min to form the eutectic phases of GdAlO_3 and Al_2O_3.The GdAlO_3 and Al_2O_3 crystal phases that formed from the amorphous phase were identified by FIB-SEM and HR-TEM.Both components began to crystallize and grow from the amorphous phase separately at different temperatures.The formation process of these crystal phases was different from that of the ordinary eutectic microstructure solidified from the GdAlO_3-Al_2O_3 system.Therefore,the observed structure is termed "eutectic-like" for distinction.The microstructures formed from the amorphous phases at sufficiently high temperatures consisted of ultra-fine microstructures of individually crystallized components and were similar to ordinary eutectic microstructures.By heat-treating the amorphous films at 1500 °C for either 2 min,8min or 30min,the ultra-fine components of GdAlO_3 and Al_2O_3 were found to crystallize following a eutectic-like stage after 8min of heat treatment.展开更多
The decomposition and precipitation behaviors of a quenched Cu-15wt%Sn alloy as a function of aging temperature were investigated using transmission electron microscopy （TEM）. Focused ion beam （FIB） was employed t...The decomposition and precipitation behaviors of a quenched Cu-15wt%Sn alloy as a function of aging temperature were investigated using transmission electron microscopy （TEM）. Focused ion beam （FIB） was employed to assist TEM specimen preparation. At 300 ℃, the decomposition of the supersaturated phase occurred at grain boundaries, displaying a cellular morphology. The lamellae were found with and phases, rather than with the equilibrium e and phases. The and phases exhibit a welldefined orientation relationship （OR） as On the other hand, at 320 ℃, only incipient lamellar structures of several micron meters were observed, which were composed of the 6 and phases. At the same time, abundant intragranular precipitation of the e phase in the form of platelets was observed, and OR as （lil）J/ （001）, [110] J/[100] exists between e phase and the ct phase. These contrasting precipitation behaviors are discussed from the viewpoint of crystallographic coherency of these phases.展开更多
基金part of the study under the "Human Resource Development Center for Economic Region Leading Industry" Projectsupported by the Ministry of Education,Science & Technology(MEST)by the National Research Foundation of Korea(NRF)
文摘The crystallization process of the eutectic composition of GdAlO_3-Al_2O_3 from the amorphous phase prepared by rapid-quenching of melt that leads to the formation of a cantaloupe skin-like microstructure was investigated using focused ion-beam scanning electron microscopy (FIB-SEM) and high-resolution transmission electron microscopy (HR-TEM).The amorphous films were heat-treated at temperatures between 1000 °C and 1500 °C for up to 30min to form the eutectic phases of GdAlO_3 and Al_2O_3.The GdAlO_3 and Al_2O_3 crystal phases that formed from the amorphous phase were identified by FIB-SEM and HR-TEM.Both components began to crystallize and grow from the amorphous phase separately at different temperatures.The formation process of these crystal phases was different from that of the ordinary eutectic microstructure solidified from the GdAlO_3-Al_2O_3 system.Therefore,the observed structure is termed "eutectic-like" for distinction.The microstructures formed from the amorphous phases at sufficiently high temperatures consisted of ultra-fine microstructures of individually crystallized components and were similar to ordinary eutectic microstructures.By heat-treating the amorphous films at 1500 °C for either 2 min,8min or 30min,the ultra-fine components of GdAlO_3 and Al_2O_3 were found to crystallize following a eutectic-like stage after 8min of heat treatment.
基金supported by the China Scholarship Council(No.2010602038)the Ministry of Science and Technology of China(No.2010DFA51650)
文摘The decomposition and precipitation behaviors of a quenched Cu-15wt%Sn alloy as a function of aging temperature were investigated using transmission electron microscopy （TEM）. Focused ion beam （FIB） was employed to assist TEM specimen preparation. At 300 ℃, the decomposition of the supersaturated phase occurred at grain boundaries, displaying a cellular morphology. The lamellae were found with and phases, rather than with the equilibrium e and phases. The and phases exhibit a welldefined orientation relationship （OR） as On the other hand, at 320 ℃, only incipient lamellar structures of several micron meters were observed, which were composed of the 6 and phases. At the same time, abundant intragranular precipitation of the e phase in the form of platelets was observed, and OR as （lil）J/ （001）, [110] J/[100] exists between e phase and the ct phase. These contrasting precipitation behaviors are discussed from the viewpoint of crystallographic coherency of these phases.
