Synthesis and Characterization of Nanocrystalline Ni50Al50−xMox (x = 0–5) Intermetallic Compound during Mechanical Alloying Process (original) (raw)
Related papers
International Journal of Engineering, 2015
The mechanical alloying process was used to synthesize the Ni50Al50−xMox nanocrystalline intermetallic compound using pure Ni and Al elemental powder. This process was carried out in the presence of various Mo contents as a micro-alloying element for various milling times. Structural changes of powder particles during mechanical alloying were studied by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Results showed that mechanical alloying in various combinations was completed after 48 h of milling time. Minimum crystallite size of the as-milled powders (∼10 nm) was achieved after introducing Mo and milling for 128 h. Also, lattice strain decreased with increasing milling time up to 48 h and again increased after 48 h of milling time. On the other hand, the presence of Mo significantly affected variation intensity of the lattice parameter and morphology of the powder particles.
Asian Journal of Nanoscience and Materials, 2018
The mechanical alloying (MA) procedure was used to synthesize the Ni50Al50 and Ni50Al45Mo5 nanocrystalline intermetallic compound using the pure Ni, Al and Mo elemental powdersunder in an argon atmosphere for different times (8, 16, 48, 80 and 128 h) in a planetary ball mill with hardened steel balls (12 balls-1cm and 4 balls-2cm in diameter). The mechanical alloying was carried out in the attendance of various Mo contents as a micro-alloying element for various milling times.Microstructural characterization and structural changes of powder particles during mechanical alloying were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Outcomes confirmed that the synthesis behavior of NiAl intermetallic depends on the milling time and Mo content. The results show that after than80hof milling, the intermetallic phase is produced after opening the vial lid. X-ray map shows that, in the fixed milling time, enhancingthe Mo content leads to acceleration in the NiAl formation in air atmosphere. The mechanical alloyed powders have a microstructure consisting of nanometer size particles. Mo enhance has a considerable effect on the lowering of crystallite size. The TEM image showed that the Ni50Al45Mo5nano-particles were less than 10 nm.The average grain size is smaller than those sizes obtained in the NiAl (25–35 nm) alloy.
Asian Journal of Nanoscience and Materials, 2018
The mechanical alloying (MA) procedure was used to synthesize the Ni50Al50 and Ni50Al45Mo5 nanocrystalline intermetallic compound using the pure Ni, Al and Mo elemental powders under an argon atmosphere for different times (8, 16, 48, 80 and 128 h) in a planetary ball mill with hardened steel balls (12 balls-1cm and 4 balls-2cm in diameter). The mechanical alloying was carried out in the attendance of various Mo contents as a micro-alloying element for various milling times. Microstructural characterization and structural changes of powder particles during mechanical alloying were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Outcomes confirmed that the synthesis behavior of NiAl intermetallic depends on the milling time and Mo content. The results show that after than 80h milling, the intermetallic phase is produced after opening the vial lid. X-ray map show that, in the fixed milling time, enhancing the Mo conte...
Metallurgical and Materials Transactions A, 2016
Ni 50 Al 50 intermetallic compound was synthesized by mechanical alloying (MA) of elemental mixtures of Ni and Al powders in a planetary ball mill. After 16 hours of milling and obtaining crystallites with a critical size, the initial NiAl compound was formed along with the combustive reaction after opening the vial lid. In the time interval of 16 to 128 hours, the reaction from combustive state reached the explosive state. Finally, after 128 hours of milling, the initial powders were wholly transformed into NiAl before completion of the milling time. Structural changes of powder particles during MA were studied by X-ray diffractometry and scanning electron microscopy. The crystallite size measurements revealed that the grain size of the NiAl phase decreased from 155 to 26 nm with increasing MA time from 8 to 128 hours. Microhardness for nanocrystalline Ni 50 Al 50 intermetallic compound produced after 128 hours of milling was measured as about 350 Hv.
In this research, the formation of nanocrystalline Ni3Al intermetallic from Ni and Al elemental powders by mechanical alloying (MA) process and its characterization was investigated. Therefore, the evolutions in microstructure such as phase transformation, oxidation in air and introduction of Fe impurity from milling media after MA were evaluated using XRD, Rietveld refinement, TEM, SEM, EDS and ICP analyses. Milling after 4 h resulted in formation of Ni3Al/Al2O3 composite in air while continuing milling time up to 8 h resulted in obtaining Ni3Al product. TEM observations along with XRD combined Rietveld , s refinement analysis confirmed obtaining a disorder structure and nanocrystals of Ni3Al embedded in an amorphous matrix after 16 h milling. Moreover, the lattice parameter of Ni3Al product and Fe contamination of powder were increased by increasing milling time.
Physica Status Solidi (c), 2010
In this work, preparation of nanocrystalline Ni3Al-based alloys by mechanical alloying process followed by hot-pressing consolidation is reported. Ni75Al20Co5 and Ni70Al25Co5 elemental powder mixtures were subjected to ball milling. Subsequently, the milling products were sintered at 1000 °C under a pressure of 7.7 GPa. The powders and the consolidated pellets were investigated by X-ray diffraction. The results obtained show that the milling products were in both cases supersaturated solid solutions Ni(Al,Co) and that during the hot-pressing consolidation they had transformed into nanocrystalline Ni3Al-based intermetallic compounds. The microhardness of the produced Ni3Al-based alloys is 918 HV0.1 in the case of Ni75Al20Co5 composition and 1033 HV0.1 in the second case. The density of compacted materials is close to the theoretical value and their open porosity is negligible. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Production of a nanocrystalline Ni3Al-based alloy using mechanical alloying
Journal of Alloys and Compounds, 2010
A new Ni 3 Al-based alloy has been successfully made via densification of mechanically alloyed powders with nominal compositions of Ni-8.14Al-7.83Cr-1.45Mo-0.01B (wt%). Mechanical alloying (MA) was carried out in a planetary ball mill under different conditions. The effect of MA on the structure of elemental powders was investigated. A Ni-based solid solution was produced after 10 h of milling that transformed to a disordered Ni 3 Al intermetallic compound with nanocrystalline structure on further milling. The rate of this transformation depended on milling variables such as mill rotation speed and milling media. The yield strength of produced alloy increased with increasing temperature up to 600 • C beyond which it decreased.
Journal of Alloys and Compounds, 2013
Mechanical alloying (MA) of the ternary Ni-Al-Cr mixtures having the Ni 50 Al 50 , Ni 25 Cr 25 Al 50 and Ni 50 Cr 25-Al 25 compositions was investigated. The structural changes of powder particles during mechanical alloying were studied by X-ray diffractometry (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results show that for all three compositions the gradual interdiffusion of elements during MA leads to the development of different phases. The final structures for the Ni 50 Al 50 and Ni 25 Cr 25 Al 50 compositions are nanocrystalline NiAl and (Ni, Cr)Al intermetallic compounds, respectively. However MA of the Ni 50 Cr 25 Al 25 composition led to the formation of a Ni 3 Al intermetallic compound as well as Cr which transformed to the (Ni, Cr) 3 Al intermetallic compound after subsequent heat treatment. The structural transition upon annealing was investigated. Furthermore, thermodynamic analysis using the Miedema model for all three systems is carried out and discussed in detail.
Acta Physica Polonica A, 2016
The subject of this study is the phase composition evolution of Ni50Ti50−xMox (x = 10, 25, 40 at.%) systems prepared by mechanical alloying in as-milled state and after subsequent heat treatment. During milling a mechanically induced solid state reaction between nickel, titanium and molybdenum was observed leading to the formation of nanocrystalline disordered solid solutions. As a result of heat treatment a creation of NiMo intermetallic phase was observed as well as structure relaxation of previously formed solid solutions.
International Journal of Electrochemical Science, 2012
Ni and Al elemental powder mixtures with composition Ni75Al25 (at %) were mechanically alloyed in a planetary ball mill under different mechanical alloying (MA) durations. X-ray diffraction (XRD), scanning electron microscope (SEM) and simultaneous thermal analysis (STA) were conducted to study phase transformations, morphology changes and thermal property of Ni-Al mixture during MA. Ni3Al intermetallic compound was formed successfully after 10h of milling, which was the shortest formation period that ever reported for this intermetallic compound. The nanocrystalline Ni3Al with the lowest crystallite size of 12.6nm was synthesized. Refinement of crystallite size with increasing internal strain was significant as milling duration was increased gradually. During formation of the Ni3Al, the powder particles have undergone incidents of welding, microforging, fracturing, rewelding and agglomeration. electrochemsci.org/papers/vol7/7043765.pdf