本文主要是利用霍普金森高速撞擊試驗機，來探討鐵錳鋁合金於高速撞擊下之破壞行為。本實驗是在測試溫度為25 ，應變速率分別為2000 s-1、3780 s-1、5760 s-1、8000 s-1下，將實驗所得到數據和微觀結果(OM、SEM)做分析，用來研究應變速率對鐵錳鋁合金之動態機械特性及其相對微觀組織變化之影響，最後再引用一合適之材料構成方程式，來描述鐵錳鋁合金在高速撞擊下之塑變行為，以做為工程模擬與分析之用。
　　由實驗的數據分析，可知鐵錳鋁合金之動態機械性質受到應變速率和應變量之影響甚鉅。在相同應變量下，應變速率增加，其塑流應力值、加工硬化係數、加工硬化率及應變速率敏感性係數隨之上升，而熱活化體積則有相反之趨勢。且在相同應變速率下，隨著應變量增加，塑流應力值及應變速率敏感性係數有上昇之現象，加工硬化率及熱活化體積則有相反之趨勢。同時，從破壞形貌觀察，可以知道在高速變形下鐵錳鋁合金之破壞模式為絕熱剪切模式，高速撞擊下可觀察到材料內部產生除了主裂縫外的絕熱剪切帶，以及剪切帶所造成試件內部的微裂縫相互連結，因而造成材料破壞之現象；在破斷面觀察上，可以發現到節點及劈裂面是主要的形貌分佈，故屬於脆性破壞，而隨著應變速率的增加，節點形貌會有不同的改變且劈裂面積增加。最後，藉由Zerilli-Armstrong模式之構成方程式，及其配合本實驗所得之材料參數，可以準確的描述鐵錳鋁合金於高速撞擊下之塑變行為。

　　This study uses the split-Hopkinson pressure bar to investigate the impact deformation and fracture behaviour of Fe-Mn-Al alloy at strain rates of 2000 s-1, 3780 s-1, 5760 s-1 and 8000 s-1 at room temperature. OM and SEM microscopy techniques are employed to analyze the fracture and microstructure characteristics of the deformed specimens in order to establish the relationships between the mechanical and the microstructural properties of the alloy. The experimental results indicate that both strain and strain rate influence the mechanical properties of the Fe-Mn-Al alloy. Under constant strain, the flow stress, work hardening coefficient, work hardening rate and strain rate sensitivity increase with increasing strain rate, while the activation volume decreases. Meanwhile, under constant strain rate, the flow stress and strain rate sensitivity increase with increasing strain, while the activation volume and work hardening rate decrease. Fractographic analysis reveals that the fracture is dominated by adiabatic shear band formation. Furthermore, dimple characteristics and cleavage facets are observed on the fracture surfaces. It is found that cleavage facture occurs more frequently with increasing strain rate. Finally, it is shown that the Zerilli-Armstrong constitutive equation with the experimentally determined specific material parameters successfully describes the flow behaviour of Fe-Mn-Al alloy under the current test conditions.

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