International Research Fellowship Program: Device Reliability and Fracture of Electroceramics

0402066琼斯国际研究奖学金计划使美国科学家和工程师能够在国外进行三到二十四个月的研究。 该计划的奖项提供了联合研究的机会，以及使用独特或互补的设施，专业知识和国外的实验条件。Jones将与澳大利亚悉尼新南威尔士大学的Mark霍夫曼博士和爱荷华州州立大学的Ersan Ustundag博士一起工作12个月。铁电材料将电能和机械能结合在一起，使其成为医疗超声成像、压电蜂鸣器、超声电机、声纳、高精度测量系统。 在医学和其他复杂应用中，铁电器件的失效，特别是断裂失效，是不可接受的。 这项研究量化了微结构在循环加载铁电器件的裂纹萌生、扩展和失效中的作用，最终提高了可靠性。使用霍夫曼博士提供的技术观察和表征了损伤引发，包括亚表面微裂纹和断裂韧性随裂纹扩展（R曲线）的变化。 微观结构参数，包括应变，纹理和成分在裂纹扩展实验过程中使用新的衍射技术广泛应用于Ustundag博士的研究在原位量化。结合这些实验结果，建立了铁电和铁弹材料损伤演化模型

0402066JonesThe International Research Fellowship Program enables U.S. scientists and engineers to conduct three to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-two month research fellowship by Dr. Jacob L. Jones to work with Dr. Mark Hoffman at the University of New South Wales in Sydney, Australia for 12 months, and Dr. Ersan Ustundag at Iowa State University for 10 months.Ferroelectric materials couple electrical and mechanical energy, making them ideal for active components in actuators, sensors and transducers in applications including medical ultrasonic imaging, piezoelectric buzzers, ultrasonic motors, sonar, and high-precision measurement systems. In medical and other sophisticated applications, failure of the ferroelectric device, particularly by fracture, is unacceptable. This research quantifies the role of microstructure in crack initiation, propagation and failure of cyclically loaded ferroelectric devices, leading ultimately to enhanced reliability. Damage initiation including subsurface microcracking and change in fracture toughness as a function of crack extension (R-curve) is observed and characterized using techniques offered by Dr. Hoffman. Microstructural parameters including strain, texture and composition are quantified in situ during crack propagation experiments using novel diffraction technologies applied extensively in Dr. Ustundag's research. The results from these experiments are combined to develop a model for damage evolution in ferroelectric and ferroelastic materials