本研究重點在於探討鎳鋁合金梯度奈米結構在奈米尺度下的機械以及材料性質。在模擬理論方法上，使用分子動力學方法與 FinnisSinclair 勢能函數與 Voronoidiagram 作為基礎理論，使用 Atomsk[1]透過 Voronoi diagram 來建構鎳鋁多晶結構，接著使用 LAMMPS[2]來進行分子動力學模擬。首先分析鎳鋁多晶結構與鎳鋁金屬玻璃結構上的差異，再選取四塊材料接合再一起形成梯度結構，接著比較多晶結構與金屬玻璃與梯度結構三者在不同溫度、負載速率、負載方向下的機械性質、應力分佈、破壞情形。此外為了測試疲勞壽命，在結構中間挖直徑一奈米的孔洞使其產生缺陷，進而探討缺陷對機械性質的影響。拉伸與剪切試驗結果顯示，均質結構含有晶粒大小愈大其強度愈高，但其延展性也會因此而降低，金屬玻璃雖然強度最低但卻擁有最好的延展性，梯度結構則是擁有較好的強度、延展性，即使是對另一不同方向進行拉伸試驗結果也是如此，在不同溫度條件下則顯示出，溫度提高可以稍微提升延展性與抗拉強度，在不同負載速率下則顯示出，速度愈快抗拉度、延展性愈大。當材料有孔洞時，從結果可以發現孔洞在不同位置對整體結構有著非常大的影響，當在大顆粒層有孔洞時，強度及延展性僅有少許下降，而在小顆粒層或金屬玻璃層有孔洞時，則會大大的下降強度及延展性。

This study investigated the mechanical and material properties of the Ni-Al metal gradient structure at the nanometer scale. In the simulation method, the molecular dynamics method and the Finnis-Sinclair potential energy function and the Voronoi diagram are used as the basic theory. The Atomsk[1] was used to construct a Ni-Al polycrystalline structure through a Voronoi diagram, followed by LAMMPS[2] for molecular dynamics simulation.
Firstly, the difference between Ni-Al polycrystalline structure and Ni-Al metallic glass structure is analyzed, and then formed a gradient structure. Then compare the mechanical properties, stress distribution and damage of polycrystalline structure and metallic glass and gradient structure at different temperatures, load rates and load directions. In addition, in order to test fatigue life, a hole is dug in the middle of the structure to cause defects. The tensile and shear test results show that the higher the grain size of the homogeneous structure, the higher the strength, but the ductility is reduced. Although metallic glass has the lowest strength but has the best ductility, the gradient structure has better strength and ductility, even in the case of tensile test in another different direction. The temperature increase can improve the ductility and tensile strength. At different load rates, it shows that the faster the speed,
the greater the tensile strength and ductility. When there is a defect in the large grain layer, the strength and ductility are only slightly decreased, and when the grain particle layer or the metallic glass layer is defective, the strength and ductility are greatly lowered.

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