奈米金屬多層膜的超硬度特性使得其在工業上被廣泛地被應用於模仁、切具上當作是保護層，延長工具的使用壽命，而調製週期是影響其硬度表現一個非常重要的結構因素。在此研究中，本文使用分子動力學模擬一個氬原子團撞擊奈米金/鎳多層膜的表面，當滿足有效撞擊條件下，撞擊過後在多層膜表面會有一個凹洞產生，並且凹洞的深度隨著奈米金/鎳多層膜調製周期的改變會不同。調製週期的範圍為1.32 nm~5.26 nm，當調製週期由1.32 nm升至3.95 nm時，隨著調製週期的上升，金/鎳多層膜所表現出來的硬度升高。在調製週期為3.95 nm時硬度達最高，隨後隨著調製週期的增加，奈米金/鎳多層膜的硬度反而下降了。 在氬原子團撞擊薄膜表面的瞬間，在金屬多層膜內會有一脈衝波出現，脈衝波是由一塑形波(Plastic Wave)及一個彈性波(Elastic Wave)共同組成，塑形波會改變薄膜原子的位置使得薄膜在撞擊過後產生形變，而彈性波並不會改變原子的位置只會增加局部薄膜原子的溫度。The maximum hardness of metallic multilayer films depends strongly on their modulation periods. In this work, molecular dynamic simulations of the impact of argon (Ar) clusters on the surface of gold (Au)/nickel (Ni) multilayer films with various modulation periods are performed to study function of the hardness and the modulation period on the nanometer scale. An Ar cluster with a high acceleration energy, 2.5 keV, makes an impact on the (111) surface of a thin film of approximately 350,000 metal atoms. Multilayered metal films were prepared from Au and Ni with a modulation period of 1.32nm-5.26nm. The simulation results reveal that when an Ar cluster with sufficient energy makes an impact on a multilayered film, and the hardness of the Au/Ni multilayered film increasing with increasing the modulation period in the range: 1.32 nm to 3.95 nm. However the hardness decreases as the modulation period from 3.95 nm to 5.26 nm. A shock wave is produced in the film and a hemispherical crater forms on the surface about 2.95 ps after the impact. The shock wave consists of a plastic and an elastic wave. The elastic wave propagates to the bottom of the film but the plastic wave is prohibited from the interface between the Au and Ni films.
