| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 103 === Dynamic impact response and microstructural characteristics of Ti-13Nb-13Zr alloy are investigated under strain rates ranging from 1×103 to 3×103 s−1 and different temperatures of 25ºC, 650ºC and 800ºC, respectively, using a compressive split-Hopkinson pressure bar. The results indicate that mechanical properties of Ti-13Nb-13Zr alloy are sensitive to temperature and strain rate. The flow stress, strain rate sensitivity and temperature sensitivity all increase with increasing strain rate, but decrease with increasing temperature. A Combined Johnson-Cook and Zerilli-Armstrong constitutive equation is used to describe the deformation behavior of Ti-13Nb-13Zr alloy under current tested conditions. Microstructural observations show that the dislocation density, α’ volume fraction and grain size are varied with strain rate and temperature. Based on the experimental results of mechanical properties and microstructural characteristics, it is found that the correlation between the dislocation density, α’ volume fraction, grain size and flow stress can be expressed using the general relation.
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