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

Metals ◽  
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.

scholarly journals X-ray spectral microanalysis of W-Ni-Fe pseudoalloy obtained from electroerosive powders

2021 ◽  
Vol 344 ◽  
pp. 01001
Author(s):  
Evgeny V. Ageev ◽  
Oxana G. Loktionova ◽  
Sergey V. Pikalov ◽  
Valeryi I. Kolmykov
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Spark Plasma Sintering ◽  
Transverse Section ◽  
Sample Surface ◽  
Sintered Sample ◽  
X Ray ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Scanning Electron

The results of X-ray spectral microanalysis of W-Ni-Fe pseudo-alloy, obtained from electroerosive powders, are presented. Consolidation of the obtained electroerosive powders was carried out by the method of spark plasma sintering using the SPS 25-10 spark plasma sintering system. Using an EDAX energy-dispersive X-ray analyzer built into a Quanta 600 FEG scanning electron microscope, characteristic X-ray spectra were obtained at various points on the sample surface and along a transverse section. As a result of the study, it was found that on the surface of the investigated sintered sample, tungsten, nickel and iron are contained as the main elements, and oxygen, copper and chromium are also present in small amounts.

scholarly journals The Glassy Structure Formation and Phase Evolution in Mechanically Alloyed and Spark Plasma-Sintered Al-TM-RE Alloys

2019 ◽  
Vol 28 (12) ◽  
pp. 7407-7418
Author(s):  
Ram S. Maurya ◽  
Tapas Laha
Keyword(s):  
Spark Plasma Sintering ◽  
Phase Evolution ◽  
Amorphous Structure ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Xrd Patterns ◽  
Sintered Alloys ◽  
The Comparative Study

AbstractThe present study deals with the comparative study of amorphization tendency of Al86Ni6Y6, Al86Ni6Y6Co2 and Al86Ni6Y4.5Co2La1.5 alloy powders via mechanical alloying performed at 300 revolution per minute with ball-to-powder ratio of 15:1 and subsequently the devitrification tendency of 300 °C and 500 °C spark plasma-sintered bulk amorphous alloys. Mechanically alloyed Al86Ni6Y6, Al86Ni6Y6Co2 and Al86Ni6Y4.5Co2La1.5 powders yielded nearly fully amorphous structure after 140, 170 and 200 h, respectively. The requirement of prolonged milling was attributed to the soft and ductile nature of aluminum with high stacking fault energy. Amorphous powders were consolidated via spark plasma sintering at 300 and 500 °C by applying a constant pressure of 500 MPa. X-ray diffraction was performed on the 300- and 500 °C-sintered samples. XRD patterns of the 300 °C-sintered alloys exhibited very-low-intensity nanocrystalline FCC-Al peak overlaying an amorphous hump evincing retention of a large amount of the amorphous phase. Enhanced devitrification tendency was reported in the 500 °C-sintered alloys; however, a major difference in the devitrification tendency of the 500 °C-sintered Al86Ni8Y6, Al86Ni6Y6Co2 and Al86Ni6Y4.5Co2La1.5 alloys was that the quinary alloy exhibited higher tendency of devitrification, which was also corroborated by performing HRTEM and analytical TEM experiment. This could be attributed to the higher probability of coupling of atoms by short-range atomic shuffling during spark plasma sintering. Vickers hardness, and relative density estimated via Archimedes’ principle, varied depending on the degree of free volume annihilation and crystallization during sintering.

scholarly journals The Extrusion and SPS of Zirconium–Copper Powders and Studies of Selected Mechanical Properties

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3560
Author(s):  
Tomasz Skrzekut ◽  
Grzegorz Boczkal ◽  
Adam Zwoliński ◽  
Piotr Noga ◽  
Lucyna Jaworska ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Intermetallic Compounds ◽  
Room Temperature ◽  
Intermetallic Phase ◽  
Extrusion Process ◽  
Strength Properties ◽  
Plasma Sintering ◽  
Copper Powders ◽  
Spark Plasma ◽  
Zirconium Copper

Zr-2.5Cu and Zr-10Cu powder mixtures were consolidated in the extrusion process and using the spark plasma sintering technique. In these studies, material tests were carried out in the fields of phase composition, microstructure, hardness and tensile strength for Zr-Cu materials at room temperature (RT) and 400 °C. Fractography analysis of materials at room temperature and 400 °C was carried out. The research took into account the anisotropy of the materials obtained in the extrusion process. For the nonequilibrium SPS process, ZrCu2 and Cu10Zr7 intermetallic compounds formed in the material at sintering temperature. Extruded materials were composed mainly of α-Zr and ZrCu2. The presence of intermetallic compounds affected the reduction in the strength properties of the tested materials. The highest strength value of 205 MPa was obtained for the extruded Zr-2.5Cu, for which the samples were cut in the direction of extrusion. For materials with 10 wt.% copper, more participation of the intermetallic phase was formed, which lowered the mechanical properties of the obtained materials. In addition to brittle intermetallic phases, the materials were characterized by residual porosity, which also reduced the strength properties.

Nanoindentation Characterization of Mechanically Alloyed Fe-Al-Si Powders

2018 ◽  
Vol 784 ◽  
pp. 15-20 ◽  
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.

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

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1020 ◽  
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.

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

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.

Sign in / Sign up

Export Citation Format

Share Document