Page 21 - PR 2014 2016 10 Materials and Nanotechnology

Materials and Nanotechnology | Progress Report 297

600°C, in constant load mode at 250 and 319 characterization of the nitride layer was per-
MPa. The techniques used in this study were formed with the aid of optical microscopy
optical microscopy and scanning electron mi- (OM) and X-ray diffraction (XRD). Tensile tests
croscopy. Fractographic analysis of the creep were performed between 600 and 1000°C and
tested samples showed necking and microcav- deformation rates between 0.0002 and 0.002 s .
-1
ities. The creep results revealed a significant The results have shown that nitrided sample
increase in material strength. present expanded fcc phase and chromium
nitride (CrN) phases. Tensile tests showed
Aiming at applications such as biomaterial, that there was no significant difference in
the effect of plasma nitriding on the Ti-6Al-4V the yield strength and elongation between
alloy in fatigue behavior has be studied. The non-nitrided and plasma-nitrided samples at
studies are being performed in the Ti-6Al-4V the same temperatures. Serrated stress–strain
alloy will be comparative in the alloy with and behavior was observed in the curves obtained
without nitriding. at 600 and 700°C, which was associated with
the dynamic strain aging effect. At 600°C, the
Ti-Al intermetallic alloyss with an Al content increase in strain rate promoted an increase
between 35 and 65 (atomic%) are usually of the amplitude and oscillation frequency of
divided into two categories: single-phase or the stress.
two-phase alloys. The first group consists ex-
clusively of the γ-TiAl phase, and the second, Evaluation of adaptation and removal
by the union of the γ-TiAl and α2-Ti3Al phases. resistance of impacted abutment in small
Single-phase alloys do not have a balanced set diameter conical dental implant
of properties. The dual phase alloys allow the
desired characteristics to be systematized by Dental implants of alloy Ti6Al4V (grade V)
means of different microstructures, which can of narrow diameter came to solve a constant
be classified into several groups: (a) partially situation in the current implantology, which
lamellar, (b) near-γ, (c) duplex and D) com- would be the installation of implants in re-
pletely lamellar. The study has focused on the duced mesiodistal spaces, mainly to allow a
microstructural characterization of Ti-Al-type final prosthesis with appropriate aesthetic
alloys (Ti-44Al-4Nb-1Mo-B and Ti-48Al-2Cr- requirement. Because it is a 2-part system,
2Nb-B). the installation of the abutment, made in the
same alloy, is performed by impaction because
Nickel based superalloys its stabilization through a screw becomes in-

consistent due to difficulties in machining
Inconel is a nickel-chromium-molybdenum such tiny components. The abutment after
superalloy with high corrosion resistance and impaction in various ways in the implants
strength at elevated temperatures. Surface were sectioned at 2 mm from the implant
modification of Inconel 625 has been carried platform and the two halves were observed in
out to improve mechanical properties at el- a scanning electron microscope (SEM)(Figure
evated temperatures. Creep and hot tensile 27), in order to measure the gap or the space
tests were performed to evaluate the me- between the implant/ abutment. Similarly,
chanical properties at elevated temperatures. after the abutments were impacted in the
The surface modification that was carried out implants, they were subjected to tensile test
was plasma nitriding. The microstructural to evaluate their required removal force. This