“…As mentioned before, a single Al atom substituting a carbon atom produces additional stress to impose the eigen stress of the thermal spike. , Due to its low stiffness, an Al cluster can dissipate some of the bombardment energy of the injecting atoms to reduce the eigen stress in the thermal spike. Thus, in range I, the sp 3 C fraction subtly decreases (or undulates) with the Al content, but it decreases sharply in range II and III.…”