Page 37 - PR 2014 2016 10 Materials and Nanotechnology

Materials and Nanotechnology | Progress Report 313

tensile strength 281 MPa, and the average elon- with the {130} plane parallel to the sample sur-
gation 4.19%. The strain hardening exponent face. Hardness increases and Young’s modulus
(n) was similar for all three sheets, averaging tends to decrease in response to increasing
0.078. The plastic strain ratios for planar an- deformation. The recrystallized sample shows
isotropy (ΔR) and for normal anisotropy were low hardness and Young’s modulus.
found to be near zero and 0.4, respectively.
Values of ΔR near zero indicate there is no The effect of texturing Al O and Al O /
2 3 2 3
earing tendency. The crystallographic texture ZrO2 surfaces using femtosecond laser has
analysis yielded four dominating components: been evaluated in terms of the roughness, wet-
Brass ({110}<112>) and Copper ({112}<111>), tability and microstructure of the substrate
which are typical of strain hardened alumi- to increase growth efficiency and adhesion of
num, Cube ({001}<100>), usually associated hydroxyapatite. Femtosecond laser treatment
with recrystallization, and Goss ({110}<001>). of these materials causes phase transformation
Such a texture would be conducive to balanced from alpha-alumina to gamma-alumina. Heat
earing. The metallographic images for all three effects during femtosecond laser treatment
sheets were alike, with constituents not ho- causes the grains to be in the nanometer scale.
mogeneously distributed and with similar Without heat effects, the grains are in the
size and chemical compositions in addition to micrometer scale. The use of femtosecond
dispersoids finely spread throughout the alu- laser permits control of the surface rough-
minum matrix. The Erichsen tests also showed ness of the alumina specimens. The higher
alike results with an average of 4.6 mm before the femtosecond laser energy, the higher is
failure. the wettability of the specimen and the total
surface energy. Specimens with laser textured
Titanium alloys offer high specific strength surfaces upon immersion in 1.5 SBF for 6 and
and excellent corrosion resistance. These char- 15 days revealed apatite layers well bonded to
acteristics make titanium alloys an excellent the substrate and without detachment. The
choice for the aerospace sector and medical adhesion of apatite to surfaces of specimens
engineering. One of the main problems with that were not textured with femtosecond laser
using metallic implants for bone replacement was inadequate.
is their relatively high Young’s modulus. The
higher stiffness of a prosthesis reduces the The production of tribological nanoscale mul-
stress applied on the bone. We study the ef- tilayer CrN/NbN coatings up to 6 μm thick by
fects of cold deformation and recrystallization Sputtering/HIPIMS has been reported in liter-
on the microstructure, texture evolution, and ature. However, high demanding applications,
mechanical properties of Ti–30Nb–4Sn alloy. such as internal combustion engine parts, need
The samples are cold rolled to reduce their thicker coatings (>30 μm). The production of
thickness by up to 85%. The most deformed such parts by sputtering would be econom-
sample is subjected to recrystallization treat- ically restrictive due to low deposition rates.
ment. The crystallographic texture is deter- In this work, nanoscale multilayer CrN/NbN
mined by X-ray pole figures. The 51% deformed coatings were produced in a high-deposition
sample shows a {203}<010> texture. The 85% rate, industrial-size, Cathodic Arc Physical Va-
deformed sample shows two texture compo- por Deposition (ARC-PVD) chamber, contain-
nents: {203}<010> and {130}<-310>, while the ing three cathodes in alternate positions (Cr/
recrystallized sample shows a fiber texture Nb/Cr). Four 30 μm thick NbN/CrN multilayer