本論文針對Ti-7.5Mo生醫鈦合金在不同溫度及應變速率下之塑性變形特性及微觀結構進行研究。利用霍普金森桿撞擊試驗機分別於溫度25℃、350℃、750℃及應變速率2000 s^-1、3500 s^-1、5500 s^-1下進行撞擊試驗，並透過OM、TEM觀察試件之微觀結構，以探討溫度與應變速率對於巨觀機械性質與微觀結構之影響。
實驗結果顯示Ti-7.5Mo在相同溫度條件下，塑流應力值隨應變速率的上升而增加；而在相同應變速率條件下，其值隨溫度的上升而下降。加工硬化率大致隨溫度或應變速率的提升而下降；應變速率敏感性係數在350℃下、2000 s^-1至3500 s^-1的條件區間有特別高的現象。溫度敏感性係數隨溫度或應變速率上升而增加，惟應變速率2000 s^-1之條件隨溫度上升而下降。本論文最後提出Kobayashi & Dodd model構成方程式來預測Ti-7.5Mo合金在不同溫度及應變速率下之塑性變形情形。
在微觀結構分析中，透過OM觀察可發現：相同溫度下，α″麻田散鐵相隨著應變速率的增加有愈加緊密之趨勢。而TEM觀察中，差排密度隨應變速率的上升而增加，並隨溫度上升而減低；且雙晶間格隨應變速率與溫度的上升而縮小。最後以關係式：〖σ-σ_0=Kρ^(1⁄2)+K〗^' d^(-1)+K^'' ∆^((-1)⁄2)，結合微觀及巨觀性質以說明差排密度、差排胞尺寸與雙晶間格對塑流應力值所造成的影響。

In this study, dynamic deformation behavior and microstructural evolution of Ti-7.5Mo biomedical alloy were fully investigated at strain rates of 2000 s^-1, 3500 s^-1, 5500 s^-1 and various temperatures of 25℃, 350℃ and 750℃ by using split-Hopkinson pressure bar. The results indicate that the flow stress and temperature sensitivity increase with increasing strain rate roughly while work hardening rate decrease. Furthermore, it is also found that flow stress and work hardening rate decrease as the temperature increases. It is worth mentioning that work hardening rates of deformed Ti-7.5Mo alloy are remarkably high at a temperature of 350℃ and strain rates of 2000 s^-1 and 3500 s^-1. In contrast, work hardening rate is lower than the other deformed conditions at a temperature of 350℃ and strain rate of 5500s^-1.The Kobayashi & Dodd model is used to describe the plastic deformation behavior of Ti-7.5Mo alloy. The microstructural observations, which include optical microscope images and transmission electron microscope images reveal that the dislocation density, twin spacing and dislocation cell size are also varied with temperature and strain rate. In describing the correlation between mechanical properties and microstructural characteristic of Ti-7.5Mo alloy, a general equation with the form : 〖σ-σ_0=Kρ^(1⁄2)+K〗^' d^(-1)+K^'' ∆^((-1)⁄2) is used.

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