Through this technique, a large variety of materials are produced such as intermetallics, extended solid solutions, quasicrystals, and amorphous phases. Īmong the above-cited methods, mechanical alloying (MA) was found to be very effective in the synthesis of Ni 50Ti 50-based nanocrystalline alloys or nanostructured powders. Meanwhile, physical techniques for producing NiTi intermetallic compound using elemental Ni and Ti powders have been reported such as conventional powder metallurgy, self-propagating high temperature synthesis, explosive shock-wave compression, and mechanical alloying (MA). Numerous methods have been used to synthesize nanocrystalline shape memory alloys (NSMAs), including ion-milling deposition, melt-spinning, high-pressure torsion, and sol-gel technique. The observed shape memory effect in NiTi alloy is mainly caused by the existence of NiTi-austenite (B2) and NiTi-martensite (B19′) phases. NiTi-based shape memory alloys have attracted great scientific and technological interests, due to their remarkable mechanical and chemical properties, such as superelasticity, shape memory behavior, good corrosion resistance, hydrogen storage ability, and good biocompatibility thereby they are very appropriate for biomedical and dentistry applications. It is observed that, for longer milling time, plastic deformations introduce a large amount of stacking faults in HCP-Ti(Ni) rather than in FCC-Ni(Ti), which are mainly responsible for the observed large amount of the amorphous phase. The crystallite size decreases to the nanometer scale while the internal strain increases. For prolonged milling time, a mixture of amorphous phase, NiTi-martensite (B19′), and NiTi-austenite (B2) phases, in addition to FCC-Ni(Ti) and HCP-Ti(Ni) solid solutions, is formed.
#RIETVELD ANALYSIS XRD SOFTWARE#
Through Rietveld refinements of X-ray diffraction patterns, phase composition and structural/microstructural parameters such as lattice parameters, average crystallite size, microstrain, and stacking faults probability (SFP) in the frame of MAUD software have been obtained. In this study, the effect of milling time on the evolution of structural and microstructural parameters is investigated. Nanostructured Ni 50Ti 50 powders were prepared by mechanical alloying from elemental Ni and Ti micrometer-sized powders, using a planetary ball mill type Fritsch Pulverisette 7.
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