Low-temperature superplasticity (LTSP) at 250 ЊC and 1 ϫ 10 Ϫ3 s Ϫ1 was observed in a 5083 Al-Mg base alloy after thermomechanical treatments (TMTs). With a higher TMT rolling strain, the fraction of high-angle grain boundaries increased, which was favorable for the further operation of grainboundary sliding (GBS) and LTSP. The near-brass {110}͗112͘, S {123}͗634͘, and Cu {112}͗111͘ texture components in the as-thermomechanically treated specimens gradually evolved into a random orientation distribution during LTSP straining from 30 to 100 pct. Static annealing at 250 ЊC itself could not alter the existing texture. The grain-misorientation distribution curves also showed that, after 100 pct LTSP elongation, the misorientation angles approached the random distribution. In the latter case, the low-, medium-, and high-angle boundaries each would partition around 10, 20, and 70 pct, respectively. When the LTSP elongation was greater than 150 pct, the macrodeformation anisotropy (R) ratio would reach a plateau value of ϳ0.8. During the initial stage, a group of over 60 grains proceeded cooperative grain-boundary sliding (CGBS); most individual grain boundaries started to slide at the later stage. It seems that it is the high-angle boundaries, not the special coincidence-site lattice (CSL) boundaries, which could govern the LTSP performance.
Cu-substituted Z-type ferrite (Ba 3 Co 2−x Cu x Fe 24 O 41 , where X = 0, 0.2, 0.4, 0.6 and 0.8) powders were synthesized using a citrate precursor method. Single Z-type phases were found by X-ray diffraction to form at a relatively low temperature of 1100-1150 • C. With an appropriate sintering aid, highly dense Cu-substituted ceramics could be obtained after sintering below 900 • C and these exhibited excellent electromagnetic properties such as high initial permeability up to 7.0 with high cutoff frequencies above 1.2 GHz. The Cu content in the composition has a significant influence not only on the magnetic properties but also on the dielectric properties of the sintered ceramics. In this paper, the effects of copper substitution on the microstructures and properties of the low-temperature-sintered Ba 3 Co 2−x Cu x Fe 24 O 41 are investigated and discussed. The dielectric constant increases with increasing Cu content, which is explained by the presence of two types of charge carriers.
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