Abstracts Book - IMRC 2018

• SA5-P008
REGULAR SURFACE PATTERNS IN POLYCRYSTALLINE
STEEL GENERATED BY LOW ENERGY ION BOMBARDMENT
Roosevelt Droppa Jr 1 , Silvia Cucatti 2 , Monica Morales 2 , Haroldo C Pinto 3 , Vinicius Antunes 2 ,
Fernando Alvarez 2
1
Universidade Federal do Abc, CCNH, Brazil. 2 Universidade Estadual de Campinas, IFGW - DFA,
Brazil. 3 Universidade de São Paulo, EESC - SMM, Brazil.
In the last years ion bombardment of solids has attracted attention due to its
potential applications to nanotechnology as a tool for inducing self-organized
patterns on surfaces. In the low energy (~1 keV) range, it has been used to clean
surfaces in vacuum, to analyze composition in depth or to prepare surfaces for
thin film deposition. Also, it has been utilized as a tool to modify surfaces in a
controlled manner, permitting the formation of different surface morphologies
depending on the properties of the material and the conditions of the ion beam.
Among the possible morphologies, the ordered patterns formed on bombarded
surfaces has caught special attention of the scientific community. This work aims
at studying the formation of such patterns in polycrystalline steel samples,
relating them to the crystal orientation of the respective surface grain where
they appear.
The topography of surfaces of polycrystalline 100Cr6 steel bombarded with Xe
ion beam at room temperature was studied and the surface patterns thus
formed were analyzed by atomic force microscopy (AFM) and scanning electron
microscopy (SEM). The crystallographic orientation of each grain was
investigated by electron backscatter diffraction (EBSD) to verify its correlation
with the different topographies found. Ion bombardment was performed at
normal incidence utilizing a DC Kauffman source in a vacuum chamber.
On the ferrite matrix surface of the steel sample four distinct topographies were
found, two of them appearing as regular patterns of inverted pyramids and
oriented ripples. It was verified that pyramidal patterns were formed only on
{100} oriented alpha-Fe grains. Such patterns, by their specific features, are not
reported in the literature to our knowledge. On the other hand, oriented ripples
are well known. Here they were associated to the {110} planes family, but their
orientations are determined by the {100} crystallographic planes.