Appl. Surf. Sci., 540, 148103 (2021) [pdf]

Ion Irradiation Induced Surface Composition Modulation in Equiatomic Binary Alloys

Byung-Hyun Kim, Sang-Pil Kim, Joonhee Kang, Yong-Chae Chung, Kyung-Suk Kim, Kwang-Ryeol Lee
 

Composition modulation by Ar bombardment on the Co_0.5Cu_0.5 alloy and the CoAl B2 phase was investigated on atomic scale by molecular dynamics simulation. The Ar bombardment on alloys at 300 K revealed that this bombardment induces a surface composition modulation in the layer-by-layer mode. In both the Co_0.5Cu_0.5 alloy and the CoAl B2 phase, the element of higher-sputtering yield is accumulated on the top surface layer, whereas it is depleted in lower layers, which is puzzling in the framework the conventional sputtering theory. A phenomenological kinetic model derived from the MD simulation results considering both the rearrangement and the sputtering of the substrate atoms successfully demonstrated that the rearrangement of the substrate atoms plays a significant role in the observed composition modulation.