Linear relation between surface roughness and work function of light alloys

The correlation between surface structures and material properties is rather complicated, and how to understand and clarify the relationship is of much significance for revealing related physical, chemical and mechanical mechanisms. In this study, the effect of surface roughness on the work function (WF) of Mg and Al alloys was investigated by scanning Kelvin probe and theoretical analysis. With the increase of surface roughness, the WF of AZ31 Mg alloy and 2198 Al alloy increased to 4.67 eV and 3.97 eV from initial 4.3 eV and 3.77 eV, respectively. Based on the least-square fitting method and the electrostatic field theory, the linear relationship between the WF and the surface roughness of the alloys was found. Owing to the effect of the surface electrostatic field, the rougher the surface of the alloys was, the larger the electrostatic potential near the rough surface was. Accordingly, the movement and transfer of the electrons were trapped and the required energy escaping from the surface was increased, resulting in the linear increase of the WF with the increase of the surface roughness. •The linear relation between surface roughness and work function of Mg and Al alloys was found.•The linear relation between the WF and surface roughness was consistent with the electrostatic field theory.•The WF of Mg alloy and Al alloy increased to 4.67 eV and 3.97 eV from initial 4.3 eV and 3.77 eV, respectively.