Topics: Fatigue Behavior of Bulk-Metallic Glasses and Composites

报告人：Prof. Peter K. Liaw  

Department of Materials Science and Engineering,

The University of Tennessee, Knoxville, USA.

报告时间：2006年4月29日上午9：00。

报告地点：焊接馆301室。

　　 Liaw教授是美国田纳西大学材料科学与工程系Endowed Ivan Racheff Chair of Excellence。他的主要研究方向是合金及复合材料的疲劳、断裂、无损评介和寿命评估方法研究，包括生物材料、高温合金、大块非晶合金、陶瓷基复合材料的加工与性能研究。Prof Liaw曾担任the TMS [The Minerals, Metals and Materials Society] 力学冶金委员会主席、ASM [American Society for Metals]流变与断裂委员会主席，现还担任TMS Awards Committee on “Application to Practice, Educator, and Leadership Awards”主席。他还是Director of the National Science Foundation [NSF] Integrative Graduate Education and Research Training [IGERT] Program、 the Director of the NSF International Materials Institutes [IMI] Program, and the Director of the NSF Major Research Instrumentation [MRI] Program at UT.

Prof Liaw曾获得多个奖项（如：Outstanding Teacher Award, the Moses E. and Mayme Brooks Distinguished Professor Award, the Engineering Research Fellow Award, the National Alumni Association Distinguished Service Professor Award, and the John Fisher Professorship at the University of Tennessee）。迄今已发表相关学术论文300 余篇，编辑出版了16本著作，并应邀在多个国际会议上做邀请报告。

Abstract:

Fatigue Behavior of Bulk-Metallic Glasses and Composites

Peter K. Liaw

Department of Materials Science and Engineering,

The University of Tennessee, Knoxville, TN 37996, USA.

Abstract

High-cycle fatigue (HCF) experiments were conducted on zirconium (Zr)-based bulk-metallic glasses (BMGs): Zr₅₀Al₁₀Cu₄₀, Zr₅₀Al₁₀Cu₃₀Ni₁₀, and Zr₅₀Cu₃₇Al₁₀Pd₃ in atomic percent. The HCF tests were performed, using an electrohydraulic machine at a frequency of 10 Hz with an R ratio of 0.1. Note that R = smin./smax., where smin. and smax. are the applied minimum and maximum stresses, respectively. The tests were conducted in air and vacuum at room temperature. A high-speed and high-sensitivity thermographic infrared (IR) imaging system has been used for the nondestructive evaluation of the temperature evolution during fatigue experiments of BMGs.  A sparking phenomenon was found at the final fracture moment of Zr₅₀Al₁₀Cu₃₀Ni₁₀ in air. The fatigue-endurance limits of Zr₅₀Cu₃₇Al₁₀Pd₃ and Zr_52.5Cu_17.9Al₁₀Ni_14.6Ti₅ were found to be greater than those of Zr₅₀Al₁₀Cu₄₀, and Zr₅₀Al₁₀Cu₃₀Ni₁₀ under uniaxial tension-tension loading.  The Resonant Ultrasound Spectroscopy technique was employed to determine the Poisson’s ratios, shear moduli, and bulk moduli of these BMGs. The ratio of the fatigue-endurance limit to the tensile strength increases with increasing the Poisson’s ratio. A possible relationship between the ratio of the fatigue-endurance limit to the tensile strength and the ratio of the shear modulus to the bulk modulus is discussed. A mechanistic understanding of the fatigue behavior of these Zr-based BMGs is suggested. Moreover, the fatigue results of BMG alloys are compared with those of conventional crystalline materials.