To better understand the fracture behavior of TA15 titanium alloy during hot forming, three groups of experiments were conducted to investigate the influence of deformation temperature, strain rate, initial microstruc...To better understand the fracture behavior of TA15 titanium alloy during hot forming, three groups of experiments were conducted to investigate the influence of deformation temperature, strain rate, initial microstructure, and stress triaxiality on the fracture behavior of TA15 titanium alloy. The microstructure and fracture surface of the alloy were observed by scanning electronic microscopy to analyze the potential fracture mechanisms under the experimental deformation conditions. The experimental results indicate that the fracture strain increases with increasing deformation temperature, decreasing strain rate, and decreasing stress triaxiality. Fracture is mainly caused by the nucleation, growth, and coalescence of microvoids because of the breakdown of compatibility requirements at the α/β interface. In the equiaxed microstructure, the fracture strain decreases with decreasing volume fraction of the primary α-phase(αp) and increasing α/β-interface length. In the bimodal microstructure, the fracture strain is mainly affected by α-lamella width.展开更多
用固相合成法制备SrNa0.5Bi4.5Ti5O18+x%(质量分数)CeO2(SNBTCx)铋层状无铅压电陶瓷,研究了CeO2掺杂对SNBTCx陶瓷微观结构和电性能的影响。结果表明,CeO2掺杂并未改变SNBTCx陶瓷的晶体结构,所有样品均为单一的铋层状结构陶瓷;CeO2掺杂...用固相合成法制备SrNa0.5Bi4.5Ti5O18+x%(质量分数)CeO2(SNBTCx)铋层状无铅压电陶瓷,研究了CeO2掺杂对SNBTCx陶瓷微观结构和电性能的影响。结果表明,CeO2掺杂并未改变SNBTCx陶瓷的晶体结构,所有样品均为单一的铋层状结构陶瓷;CeO2掺杂没有使SNBTCx陶瓷居里温度发生明显变化,居里温度均高于560℃;随着CeO2掺杂量的增加SNBTCx陶瓷材料的介电常数减小,但是其介电损耗先增大后减小。当CeO2掺杂量为0.3%(质量分数)时SNBTC0.03陶瓷具有最优电性能:Tc=567℃,d33=29 p C/N,tanδ=0.015,且在500℃退极化处理后,其d33仍保持在22 p C/N以上,说明SNBTC0.03陶瓷可在高温下应用。展开更多
基金financially supported by the Research Fund for the Doctoral Program of Higher Education of China(No.20120006110017)
文摘To better understand the fracture behavior of TA15 titanium alloy during hot forming, three groups of experiments were conducted to investigate the influence of deformation temperature, strain rate, initial microstructure, and stress triaxiality on the fracture behavior of TA15 titanium alloy. The microstructure and fracture surface of the alloy were observed by scanning electronic microscopy to analyze the potential fracture mechanisms under the experimental deformation conditions. The experimental results indicate that the fracture strain increases with increasing deformation temperature, decreasing strain rate, and decreasing stress triaxiality. Fracture is mainly caused by the nucleation, growth, and coalescence of microvoids because of the breakdown of compatibility requirements at the α/β interface. In the equiaxed microstructure, the fracture strain decreases with decreasing volume fraction of the primary α-phase(αp) and increasing α/β-interface length. In the bimodal microstructure, the fracture strain is mainly affected by α-lamella width.
文摘用固相合成法制备SrNa0.5Bi4.5Ti5O18+x%(质量分数)CeO2(SNBTCx)铋层状无铅压电陶瓷,研究了CeO2掺杂对SNBTCx陶瓷微观结构和电性能的影响。结果表明,CeO2掺杂并未改变SNBTCx陶瓷的晶体结构,所有样品均为单一的铋层状结构陶瓷;CeO2掺杂没有使SNBTCx陶瓷居里温度发生明显变化,居里温度均高于560℃;随着CeO2掺杂量的增加SNBTCx陶瓷材料的介电常数减小,但是其介电损耗先增大后减小。当CeO2掺杂量为0.3%(质量分数)时SNBTC0.03陶瓷具有最优电性能:Tc=567℃,d33=29 p C/N,tanδ=0.015,且在500℃退极化处理后,其d33仍保持在22 p C/N以上,说明SNBTC0.03陶瓷可在高温下应用。
