17-03-2014, 08:05 PM
Abstract—In this paper, we try to measure the differences
among the indentations of single crystal bulks under different
rotation angles by nanoindentation test. Besides, we also give a
design of positioning device for the nanoindentation measuring
system. It is driven by stepping motors and relevant circuits
for controlling the rotations of the wafer supporting platform.
The drive circuit is connected with microprocessors. The
rotation angle of the platform can be adjusted by instructions
so that the system can be used to carry out nanoindentation
tests in different angles for more precise mechanical properties
data of the nanoindentation materials.
Keywords- Nanoindentation; Automatic positioning device;
Directivity effect; Single crystal
I. INTRODUCTION
Nanoindentation is a new technology developed for
evaluating the mechanical properties of the materials in
nanometer level. Ever since the nanoindentation tester was
invented, a lot of studies had been carried out throughout the
world on the mechanical properties of the layer which was
only a few nanometers in depth under the surface of the
material. In recent years, the studies and discussions on the
nanoindentation hardness effects of the single crystal and
polycrystalline materials were focused on the following
domains. For polycrystalline material nanoindentation,
Soifer et al. [1] used to carry out nanoindentation tests with
highly purified polycrystalline copper, in order to find out
the impact of the crystal boundary on the nanoindentation
hardness. Their results indicated that the nanoindentation
hardness turned out to be increasing towards the crystal
boundary. Therefore, they proposed that if the size of crystal
grain was reduced, the number of crystal boundaries would
be increasing. Correspondingly, the strength of the material
would be enhanced. The crystal boundaries could be
regarded as obstacles for the movement of dislocations. For
single crystal nanoindentation, Kulkarni et al. [2] used to
carry out size effect experiment on the nanoindentation of
single crystal aluminum in 1996. The results indicated that
the nanoindentation hardness would drop when the load is
increasing. In 2002, Fedorov et al. [3] proposed a theoretic
model for dislocation pile-up on the crystal boundary among
nanometer crystal, polycrystalline material, and crystal grain.
At the same time, it also showed that the movement of grain
boundary dislocations was a key factor for the plastic
deformation. In 1999, Mante et al. [4] used to carry out
nanoindentation experiments on single crystal and
polycrystalline titanium. They were searching for a better
crystallization direction, which may be helpful in the study
of osteocyte attachment and improve the transplant
technology. The results told us that the modulus of elasticity
for single crystal titanium was close to that of polycrystalline
titanium. However, they were different in hardness because
of the differences in the directions of crystallographic plane.
Besides, it was also found that the oxide layer on the
titanium might change the indentation hardness.
among the indentations of single crystal bulks under different
rotation angles by nanoindentation test. Besides, we also give a
design of positioning device for the nanoindentation measuring
system. It is driven by stepping motors and relevant circuits
for controlling the rotations of the wafer supporting platform.
The drive circuit is connected with microprocessors. The
rotation angle of the platform can be adjusted by instructions
so that the system can be used to carry out nanoindentation
tests in different angles for more precise mechanical properties
data of the nanoindentation materials.
Keywords- Nanoindentation; Automatic positioning device;
Directivity effect; Single crystal
I. INTRODUCTION
Nanoindentation is a new technology developed for
evaluating the mechanical properties of the materials in
nanometer level. Ever since the nanoindentation tester was
invented, a lot of studies had been carried out throughout the
world on the mechanical properties of the layer which was
only a few nanometers in depth under the surface of the
material. In recent years, the studies and discussions on the
nanoindentation hardness effects of the single crystal and
polycrystalline materials were focused on the following
domains. For polycrystalline material nanoindentation,
Soifer et al. [1] used to carry out nanoindentation tests with
highly purified polycrystalline copper, in order to find out
the impact of the crystal boundary on the nanoindentation
hardness. Their results indicated that the nanoindentation
hardness turned out to be increasing towards the crystal
boundary. Therefore, they proposed that if the size of crystal
grain was reduced, the number of crystal boundaries would
be increasing. Correspondingly, the strength of the material
would be enhanced. The crystal boundaries could be
regarded as obstacles for the movement of dislocations. For
single crystal nanoindentation, Kulkarni et al. [2] used to
carry out size effect experiment on the nanoindentation of
single crystal aluminum in 1996. The results indicated that
the nanoindentation hardness would drop when the load is
increasing. In 2002, Fedorov et al. [3] proposed a theoretic
model for dislocation pile-up on the crystal boundary among
nanometer crystal, polycrystalline material, and crystal grain.
At the same time, it also showed that the movement of grain
boundary dislocations was a key factor for the plastic
deformation. In 1999, Mante et al. [4] used to carry out
nanoindentation experiments on single crystal and
polycrystalline titanium. They were searching for a better
crystallization direction, which may be helpful in the study
of osteocyte attachment and improve the transplant
technology. The results told us that the modulus of elasticity
for single crystal titanium was close to that of polycrystalline
titanium. However, they were different in hardness because
of the differences in the directions of crystallographic plane.
Besides, it was also found that the oxide layer on the
titanium might change the indentation hardness.