Title:Mechanics and Pattern Transfer of Imprinted NiAl Amorphous Films Investigated Using Atomistic Simulation
Volume: 13
Issue: 2
Author(s): Cheng-Da Wu, Te-Hua Fang, Ming-Hong-Lin and Jih-Kai Su
Affiliation:
Keywords:
Amorphous metals, molecular dynamics, nanoimprinting, NiAl, shear strain.
Abstract: Background: Amorphous NiAl alloys, whose atomic arrangement is disordered, have
attracted a lot of attention due to their unique physical properties, such as high mechanical strength
and hardness, high toughness, low friction, good corrosion resistance, and minimal shrinkage. The
alloys have excellent corrosion resistance at high temperature and thus are often used in blade coatings.
Nanoimprinting lithography (NIL) is an accessible and low-cost technique for fabricating various
components on micro- and nanometer scales.
Methods: The purpose of this work is to quantitatively study the forming and mechanics properties
of the amorphous NiAl films during the NIL process utilizing the molecular dynamics (MD) simulations.
The effects of taper angle of mold cavities, interval between mold cavities, and annealing temperature
on amorphous NiAl films are studied.
Results: The results are discussed in terms of atomic trajectories, shear strain, imprinting force, and
elastic recovery of imprinted films. The study contributes to a better understanding of the amorphous
material forming mechanisms and mechanics at the nanoscale. MD simulations were used to investigate
the effect of taper angle of mold cavities, mold cavity interval, and annealing temperature on
amorphous NiAl films. The required imprinting force and adhesion force between the mold and imprinted
films increase with decreasing mold cavity interval.
Conclusion: Undesired elastic recovery of patterns can be reduced by using molds with smaller taper
angles and cavity intervals. During imprinting, film atoms with high shear strain values are mainly
distributed in areas with a geometric discontinuity of mold, forming significant defects. Thermal
annealing effectively decreases the shear strain of imprinted films; however, it increases the elastic
recovery of patterns, especially in the area at the top of a pattern.
