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Ball milling induced the formation of nanocrystalline and amorphization phase in Fe–25.68% Dy2O3 powder mixtures (mass fraction, %). The microstructure was investigated by using X-ray diffraction and transmission electron microscopy. The transformation of Dy2O3 from cubic to monoclinic crystal structure and then to the amorphization was observed during ball milling. A few Dy atoms were dissolved into Fe crystal structure, which was discussed using mechanical kinetics. After 48 h of ball milling, the homogenous mixtures of supersaturated nanocrystalline solid solution of Fe (Dy, O) and Dy2O3 amorphization were formed and the elements of Fe, Dy, and O were distributed uniformly in the ball-milled particles. During the whole ball mining process, a rapid decrease in Fe grain size was observed over the initial time period, while a constant value was presented in later stage, resulting in a final size of about 20 nm. The mechanism of the microstructural evolution of powder mixtures was analyzed and discussed.
Two types of pyrite framboids (PF, probably sulphate-reducing bacteria) have been found within the Zoophycos spreiten, hosted in the Guadalupian (Middle Permian) glaciomarine greywacke of the Westley Park Sandstone Member within the Broughton Formation from the southern Sydney Basin of southeastern Australia. They are composed of non-sheathed (PF1) and sheathed (PF2) sub-micron balls, respectively. Chemically, the sub-micron balls consist of iron, sulphur, carbon and oxygen. Both PF1 and PF2 occur in rhythmic alternation within the thick, light-grey and thin, dark-grey minor lamellae of Zoophycos spreiten. The framboids from the minor lamellae are highly abundant and occur in an orderly arrangement of equal density and in a good state of preservation. Within Zoophycos spreiten no homogeneous filling, fecal pellets, or any sign of re-exploitation of the minor lamellae have been recognized. No similar framboids have been observed outside Zoophycos spreiten. Therefore, the framboids are interpreted as the pyritized remains of microbial colonies within Zoophycos spreiten. The trace Zoophycos would be a multifunctional garden that may have been carefully constructed by the Zoophycos maker, where different microbial colonies were orderly and carefully planted and cultured within different minor lamellae. Further, it is proposed that the Zoophycos maker had a symbiotic relationship with microbial colonies on the mutual basis of food supply and redox conditions. The fact that the overlying spreiten cut the underlying ones indicates that the Zoophycos from the study area is of an upward construction. The rhythmic alternation of both the thick, light-grey and thin, dark-grey minor lamellae within Zoophycos spreiten may be suggestive of a gardening manner of the Zoophycos maker responding to the warm and cold changes, food supply in pulses and variations of sedimentation rate for planting and culturing microbial colonies under the conditions of a glaciomarine environment at the high latitudes.
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