Structural Evolution in Mechanically Alloyed and Spark Plasma Sintered Iron–0.15 wt.% MWCNT Composite

In the present study, the effect of wet mechanical alloying (MA) on the glass-forming ability (GFA) of Co43Fe20X5.5B31.5 (X = Ta, W) alloys was studied. The structural evolution during MA was investigated using high-energy X-ray diffraction, X-ray absorption spectroscopy, high-resolution transmission electron microscopy and magnetic measurements. Pair distribution function and extended X-ray absorption fine structure spectroscopy were used to characterize local atomic structure at various stages of MA. Besides structural changes, the magnetic properties of both compositions were investigated employing a vibrating sample magnetometer and thermomagnetic measurements. It was shown that using hexane as a process control agent during wet MA resulted in the formation of fully amorphous Co-Fe-Ta-B powder material at a shorter milling time (100 h) as compared to dry MA. It has also been shown that substituting Ta with W effectively suppresses GFA. After 100 h of MA of Co-Fe-W-B mixture, a nanocomposite material consisting of amorphous and nanocrystalline bcc-W phase was synthesized.

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Crystallization Kinetics and Consolidation of Al82La10Fe4Ni4 Glassy Alloy Powder by Spark Plasma Sintering

Metals ◽

10.3390/met8100812 ◽

2018 ◽

Vol 8 (10) ◽

pp. 812

Author(s):

Nguyen Viet ◽

Nguyen Oanh ◽

Ji-Soon Kim ◽

Alberto Jorge

Keyword(s):

Nucleation Rate ◽

Glassy Alloy ◽

Intermetallic Phase ◽

Three Dimensional ◽

Sample Surface ◽

Sintered Sample ◽

Amorphous Structure ◽

Mechanically Alloyed ◽

Plasma Sintering ◽

Spark Plasma

The mechanically alloyed Al82La10Ni4Fe4 glassy powder displays a two-step devitrification characterized by the precipitation of fcc-Al together with small amounts of the intermetallic Al11La3 phase in the first crystallization. The interface-controlled growth mechanism governed the first crystallization event. Calculations of the activation energy, using the methods of Kissinger, Ozawa, and Augis-Bennett gave values of 432.33, 443.2, and 437.76 kJ/mol, respectively. The calculated Avrami exponent (n) for the first crystallization peak was about 1.41, suggesting an almost zero nucleation rate. On the other hand, the value of n for the second peak related to the residual amorphous phase completely transformed into the intermetallic phase Al11La3 was about 3.61, characterizing diffusion controlled three-dimensional crystal growth with an increasing nucleation rate. Samples sintered at 573 K kept an amorphous structure and exhibited a high compressive strength of 650 MPa with a maximum elongation of 2.34% without any plastic deformation. The failure morphology of the sintered sample surface presented a transparticle fracture mechanism, indicating the efficiency of the sintering processing.

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Structural Evolution in Mechanically Alloyed Fe-Sn

Mössbauer Spectroscopy in Materials Science ◽

10.1007/978-94-011-4548-0_15 ◽

1999 ◽

pp. 151-160 ◽

Cited By ~ 4

Author(s):

G. A. Dorofeev ◽

G. N. Konygin ◽

E. P. Yelsukov ◽

I. V. Povstugar ◽

A. N. Streletskii ◽

...

Keyword(s):

Structural Evolution ◽

Mechanically Alloyed

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Structural evolution of mechanically alloyed nanocrystalline Fe–28Al powders

Powder Technology ◽

10.1016/j.powtec.2004.11.001 ◽

2005 ◽

Vol 149 (2-3) ◽

pp. 121-126 ◽

Cited By ~ 23

Author(s):

Run-hua Fan ◽

Jia-tao Sun ◽

Hong-yu Gong ◽

Kang-ning Sun ◽

Wei-min Wang

Keyword(s):

Structural Evolution ◽

Mechanically Alloyed

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Nanoindentation Characterization of Mechanically Alloyed Fe-Al-Si Powders

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.784.15 ◽

2018 ◽

Vol 784 ◽

pp. 15-20 ◽

Cited By ~ 3

Author(s):

Petr Haušild ◽

Jaroslav Čech ◽

Miroslav Karlík ◽

Filip Průša ◽

Pavel Novák ◽

...

Keyword(s):

Mechanical Properties ◽

Mechanical Alloying ◽

Preparation Technique ◽

X Ray Diffraction ◽

Mechanically Alloyed ◽

Microstructure And Mechanical Properties ◽

Plasma Sintering ◽

Special Sample Preparation ◽

Spark Plasma ◽

Powder Particles

The effect of processing conditions on microstructure and mechanical properties of Fe-Al-Si powders was studied by means of scanning electron microscopy, X-ray diffraction and nanoindentation. Fe-Al-Si alloy powder was prepared from pure elemental powders by mechanical alloying. Microstructure and mechanical properties of powders were characterized after various durations of mechanical alloying. Special sample preparation technique was developed allowing to characterize the properties of individual powder particles after each step of processing in a planetary ball mill. This step-by-step characterization allowed to find the optimum conditions for subsequent spark plasma sintering.

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Application of Hydride Process in Achieving Equimolar TiNbZrHfTa BCC Refractory High Entropy Alloy

Crystals ◽

10.3390/cryst10111020 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1020 ◽

Cited By ~ 1

Author(s):

Bhupendra Sharma ◽

Kentaro Nagano ◽

Kuldeep Kumar Saxena ◽

Hiroshi Fujiwara ◽

Kei Ameyama

Keyword(s):

Titanium Hydride ◽

Single Phase ◽

Strengthening Mechanism ◽

High Entropy Alloy ◽

Mechanically Alloyed ◽

High Entropy ◽

Plasma Sintering ◽

Bcc Structure ◽

Spark Plasma ◽

Tih2 Powder

For the first time, an equiatomic refractory high entropy alloy (RHEA) TiNbZrHfTa compact with a single-phase body-centered cubic (BCC) structure was fabricated via a titanium hydride (TiH2) assisted powder metallurgy approach. The constituent pure Ti, Zr, Nb, Hf, and Ta powders were mechanically alloyed (MA) with titanium hydride (TiH2) powder. The resultant MA powder was dehydrogenated at 1073 K for 3.6 ks and subsequently sintered through spark plasma sintering (SPS). Additionally, TiNbZrHfTa counterparts were prepared from pure elements without MA with TiH2. It was observed that the compact prepared from pure powders had a chemically heterogeneous microstructure with hexagonal close packed (HCP) and dual BCC phases. On the other hand, despite containing many constituents, the compact fabricated at 1473 K for 3.6 ks via the hydride approach had a single-phase BCC structure. The Vickers microhardness of the TiNbZrHfTa alloy prepared via the hydride process was Hv 520 (±30). The exceptional microhardness of the alloy is greater than any individual constituent, suggesting the operation of a simple solid-solution-like strengthening mechanism and/or precipitation hardening. In addition, the heat treatments were also carried out to analyze the phase stability of TiNbZrHfTa prepared via the hydride process. The results highlight the substantial changes in the phase as a function of temperature and/or time.

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Characterization and Production of Structurat Ceramics in the Systems Fe(1-X)O-Fe3O4 and MgO-MgFe2O4.

Microscopy and Microanalysis ◽

10.1017/s1431927600017372 ◽

1999 ◽

Vol 5 (S2) ◽

pp. 810-811

Author(s):

A. Huerta ◽

R. Ordoñez ◽

H.A. Calderon ◽

M. Umemoto ◽

K. Tsuchiya ◽

...

Keyword(s):

Ceramic Materials ◽

Grain Structure ◽

Second Phase ◽

Magnetic Recording Media ◽

Mechanically Alloyed ◽

Ceramic Oxides ◽

Plasma Sintering ◽

Structural Applications ◽

Spark Plasma ◽

Second Phases

Ceramic materials are widely studied for their high temperature structural applications. In many crystalline ceramics the range of solid solution decreases with temperature and thus precipitation of a second phase occurs. Thus, ceramics can be hardened by precipitation of second phases. However little is known regarding the effect of precipitation and nanocrystalline grain structure in the ductility of ceramic materials. On the other hand, oxide ceramics are under intense-investigation for their technological advantages in magnetization, dielectric response and chemical stability in such diverse uses as magnetic recording media, induction cores and microwave resonant circuits. This investigation has been undertaken to produce, characterize and measure the properties of ceramics that can be hardened by precipitation. The selected systems include Fe(1-x)O-Fe3 and MgO MgFe2O4. Mechanical milling is used to produce nanocrystalline ceramic oxides in the systems Fe(1-x)O-Fe3 and MgO-MgFe2O4 The mechanically alloyed powders are consolidated by means of spark plasma sintering (SPS) at temperatures ranging from 673 K to 1273 K and a pressure varying from 500 to 50 MPa in vacuum.

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