Effects of Minor Elements Additions to the Nanocrystalline FeAl Alloy Produced by Powder Metallurgy

2020 ◽  
Vol 1005 ◽  
pp. 3-9
Author(s):  
Zineb Hamlati ◽  
Fadhéla Otmane ◽  
H. Mechri ◽  
W. Laslouni ◽  
Mohammed Azzaz

Mechanical alloying has recently attracted considerable attention as researchers try to improve materials properties. The process can be performed at room temperature and homogeneous alloys can be produced. In this work Fe–28 wt. % Al; Fe–26 wt. % Al–2 wt. % Sn and Fe–26 wt. % Al–2 wt. % V alloys were synthesized by mechanical alloying to investigate the effects of tin and vanadium additions on the structural and microstructural properties of Nanocrystalline FeAl Alloy. Fe72Al28, Fe72Al26Sn2 and Fe72Al26Sn2 were ball milled for 30 h under argon atmosphere using a rotating speed of 200 rpm with 15 min pause time after every 15 min running time. The structural and microstructural properties of the ball milled powders were analyzed using X-ray diffraction (DRX) and Mössbauer spectroscopy techniques. The final powders are characterized by an average crystallite size of 10 nm for the Fe72Al28 alloy, 6 nm for the Fe72Al26Sn2 alloy and 19 nm for the Fe72Al26V2, accompanied by the introduction of a lattice strain of order of 1.55 %, 0.78 % and 0.80% respectively. The Mossbauer study of the Fe72Al26V2 samples showed doublet with isomer shift IS= 0.17 mm/s and three magnetically split sextet.

1988 ◽  
Vol 133 ◽  
Author(s):  
K. S. Kumar ◽  
S. K. Mannan

ABSTRACTThe mechanical alloying behavior of elemental powders in the Nb-Si, Ta-Si, and Nb-Ta-Si systems was examined via X-ray diffraction. The line compounds NbSi2 and TaSi2 form as crystalline compounds rather than amorphous products, but Nb5Si3 and Ta5Si3, although chemically analogous, respond very differently to mechanical milling. The Ta5Si3 composition goes directly from elemental powders to an amorphous product, whereas Nb5Si3 forms as a crystalline compound. The Nb5Si3 compound consists of both the tetragonal room-temperature α phase (c/a = 1.8) and the tetragonal high-temperature β phase (c/a = 0.5). Substituting increasing amounts of Ta for Nb in Nb5Si3 initially stabilizes the α-Nb5Si3 structure preferentially, and subsequently inhibits the formation of a crystalline compound.


2013 ◽  
Vol 12 (01) ◽  
pp. 1350006
Author(s):  
AHMED E. HANNORA ◽  
FARIED F. HANNA ◽  
LOTFY K. MAREI

Mechanical alloying (MA) method has been used to produce nanocrystallite Mn -15at.% Al alloy. X-ray diffraction (XRD) patterns for the as-milled elemental α- Mn and aluminum powder samples show a mixture of α + β- MnAl phases after 20 h of milling and changes to a dominant β- MnAl phase structure after 50 h. An average crystallite size of 40 nm was determined from Hall–Williamson method analysis after 5 h of milling. Moreover, the thermal analysis results using differential thermal analysis (DTA), suggested a possible phase transformation after 20 h of milling. Isothermal treatments are carried in the temperature range of 450°C to 1000°C. Room-temperature vibrating sample magnetometer (VSM) measurements of the hysteretic response revealed that the saturation magnetization Bs and coercivity Hc for 10 h ball milled sample are ~ 2.1 emu/g and ~ 92 Oe, respectively.


2017 ◽  
Vol 31 (02) ◽  
pp. 1750006 ◽  
Author(s):  
Mohammad Hossein Ghorbani ◽  
Abdol Mahmood Davarpanah

Manganese oxides are of more interest to researchers because of their ability as catalysts and lithium batteries. In this research, MnO2nanowires with diameter about 45 nm were synthesized by sol–gel method at room temperature (RT). Effect of increasing the annealing temperature from 400[Formula: see text]C to 600[Formula: see text]C on crystalline structure of nanostructure were studied and average crystallite size was estimated about 22 nm. X-ray Diffraction (XRD) method, Energy-Dispersive X-ray Diffraction (EDXD), Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM) were used to characterize the nanowires of MnO2.


Author(s):  
Nakib Chafika

B2-structured (Fe,Ni)Al was synthesised by an abrupt reaction during mechanical alloying (MA) of the elemental powders of Fe, Al and Ni. The structural, microstructural, morphological and magnetic changes occurring in the studied material during MA were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Two crystalline phases were found, a majority one corresponding to (Fe,Ni)Al bcc phase with a crystallite size less than 10 nm, a lattice strain up to 1.6% and a dislocation density of about 2.3 x1016 m-2. The other phase was in a low proportion corresponding to Fe (Al,Ni) solid solution. SEM images showed an irregular morphology of powder particles. Mossbauer spectra of the milled powders, recorded at room temperature, reveal the paramagnetic behaviour of the obtained powder. Keywords: Mechanical alloying, ternary composition, dislocation density, structural properties, paramagnetic behaviour.


2006 ◽  
Vol 6 (11) ◽  
pp. 3429-3432
Author(s):  
Chung-Hyo Lee ◽  
Seong-Hee Lee ◽  
Sung-Yong Chun ◽  
Sang-Jin Lee

A mixture of pure Mg and Si powders with an atomic ratio 2:1 has been subjected to mechanical alloying (MA) at room temperature to prepare the Mg2Si thermoelectric material. Mg2Si intermetallic compound with a grain size of 50 nm can be obtained by MA of Mg66.7Si33.3 powders for 60 hours and subsequently annealed at 620 °C. Consolidation of the MA powders was performed in a spark plasma sintering (SPS) machine using graphite dies up to 800–900 °C under 50 MPa. The shrinkage of consolidated samples during SPS was significant at about 250 °C and 620 °C. X-ray diffraction data shows that the SPS compact from 60 h MA powders consolidated up to 800 °C consists of only nanocrystalline Mg2Si compound with a grain size of 100 nm.


Author(s):  
Mahmoud Chemingui ◽  
Chahida Mnasri ◽  
Christelle Nivot ◽  
Arnaud Tricoteaux ◽  
Yannick Lorgouilloux ◽  
...  

Abstract A new nanocrystalline Fe71B23Nb6 alloy powder was prepared by mechanical alloying. The phase transformation and morphological and microstructural properties of the as-prepared alloy were investigated by scanning electron microscopy, laser granulometry, and X-ray diffraction with respect to the milling time (0- 200 h). During the milling process, it was observed that the dissolution of Nb and B atoms into the Fe matrix formed solid solutions of Fe (Nb), Fe (B), Fe23B6, Fe2B, and Fe (Nb, B). Moreover, the insertion of B atoms into the Nb network generated the Nb (B) phase. Furthermore, the minimum crystallite size was measured as approximately 1 nanometer. In addition, the dislocation density gradually increased with the extension of the milling time, and the crystallization of the partially amorphous phase occurred after 200 h of milling.


2000 ◽  
Vol 15 (10) ◽  
pp. 2080-2086 ◽  
Author(s):  
L. E. Depero ◽  
A. Marino ◽  
B. Allieri ◽  
E. Bontempi ◽  
L. Sangaletti ◽  
...  

The effects of doping on the morphological and microstructural properties of TiO2 nanopowders produced by laser pyrolysis were investigated mainly by x-ray diffraction (XRD) and electron microscopy. Samples of TiO2 powders were prepared by doping with different trivalent cations (Al and Ga). The powders were calcined at different temperatures in the range 400–1000 °C for 18 h, as well as at constant T = 700 °C up to 160 h. After each thermal treatment, XRD patterns were collected. The analysis of XRD patterns allowed us to estimate the microstrains and average crystallite size and to observe the evolution of the microstructural parameters with temperature. Both Al and Ga inhibited the crystallite growth of TiO2 anatase and the rutile phases, this effect being larger in the Al-doped powders.


2020 ◽  
Vol 38 (3B) ◽  
pp. 85-97
Author(s):  
Abdulqader D. Faisal ◽  
Mofeed A. Jaleel ◽  
Fahad Z. Kamal

Zinc oxide flower-like nanorods (ZnO NRs) was successfully synthesized via the hydrothermal method. The growth process was conducted with seed layer concentrations of 20mM. The as-synthesized nanostructures were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), and ultraviolet-visible (UV-VIS) spectrophotometer. The analysis results revealed a pure Wurtzite ZnO hexagonal nanostructures with preferred orientation (002) along the c-direction. The calculated band gap of average crystallite size is 3.2eV and 25 nm respectively. New designed, constructed and successfully calibrated for ethanol gas sensing was found. The ethanol gas sensor was fabricated at room temperature based on the ZnO NRs film. The synthesized materials proved to be a good candidate for the ethanol gas sensor. The optimum results of the gas sensor measurements of the synthesized gas sensor are as follows, the sensitivity, response time, and recovery time at 25 °C are 60%, 80 Seconds and 80 seconds respectively, and at 200 °C are 70%, 60 seconds and 50 seconds respectively.


2015 ◽  
Vol 1123 ◽  
pp. 109-113
Author(s):  
Rindang Fajarin ◽  
Hariyati Purwaningsih ◽  
Febri Nugroho

PbTiO3is one of electroceramic materials which can be applied for electronics and microelectronics due to their dielectric, pyroelectric, and piezoelectric properties. The members of PbTiO3-based ferroelectrics are widely used in multilayer, actuator and sensor capacitor. At room temperature, PbTiO3has a tetragonal perovskite structure. In this research, PbTiO3particles are synthesized by mechanical alloying method with variation of milling time and sintering temperature. The milling time variation is taken for 10, 20 and 30 hours. Sintering temperature variation is performed at 850, 900 and 1000°C. The powders used in the milling process are PbO and TiO2powders. X-Ray Diffraction (XRD) and Scanning Electron Microscopy–Electron Difraction X-ray (SEM-EDX) are performed to analyze the formation of PbTiO3phase. It is found that the synthesized powders contain 100% PbTiO3phase for all sintering temperatures. The PbTiO3particles have agglomeration shape with a broad particle size. The electrical properties of PbTiO3are measured using electrical test device. Electricity test analysis shows that the synthesized PbTiO3behaves as semiconductor-like.


2017 ◽  
Vol 49 (3) ◽  
pp. 277-284 ◽  
Author(s):  
Zorica Lazarevic ◽  
Cedomir Jovalekic ◽  
Martina Gilic ◽  
Valentin Ivanovski ◽  
Ana Umicevic ◽  
...  

Yttrium orthoferrite (YFeO3) powder was prepared by a mechanochemical synthesis from a mixture of Y2O3 and ?-Fe2O3 powders in a planetary ball mill for 2.5 h. The obtained YFeO3 powder sample was characterized by X-ray diffraction (XRD), Raman and infrared spectroscopy. The average crystallite size calculated by the Scherrer equation was 12 nm. The M?ssbauer spectroscopy at room temperature confirms the superparamagnetic character of YFeO3 orthoferrite sample.


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