The effect of mechanical activation of the reaction mixture on the formation of the microstructure of ZrB2‒CrB composites obtained by electrothermal explosion under pressure

2019 ◽  
pp. 61-64
Author(s):  
A. V. Shcherbakov ◽  
V. A. Shcherbakov ◽  
V. Yu. Barinov ◽  
S. G. Vadchenko ◽  
A. V. Linde
Keyword(s):  
Mechanical Activation ◽  
Relative Density ◽  
Powder Mixture ◽  
Ceramic Composite ◽  
Initial Powder ◽  
Electrothermal Explosion ◽  
Homogeneous Microstructure ◽  
Fine Ceramic ◽  
Ceramic Bond

Composites ZrB2‒CrB with a ceramic bond content of 80 wt. % and relative density 0,85‒0,90 were obtained by the method of electrothermal explosion (ETЕ) under pressure. It is shown that mechanical activation (MA) of the initial powder mixture reduces its heterogeneity and increases its reactivity. A fine ceramic composite with a homogeneous microstructure was obtained containing needle-like ZrB2 grains. Ill. 5. Ref. 13.

In situ synchrotron research of phase formation in mechanically activated 3Ti + Al powder composition during high-temperature synthesis under the condition of heating with high-frequency electromagnetic fields

2019 ◽  
Vol 26 (2) ◽  
pp. 422-429 ◽  
Author(s):  
Marina Loginova ◽  
Alexey Sobachkin ◽  
Alexander Sitnikov ◽  
Vladimir Yakovlev ◽  
Valeriy Filimonov ◽  
...  
Keyword(s):  
High Temperature ◽  
Mechanical Activation ◽  
Phase Formation ◽  
Powder Mixture ◽  
Inductive Heating ◽  
Initial Powder ◽  
Temperature Synthesis ◽  
Powder Composition ◽  
High Temperature Synthesis

An in situ synchrotron study of the specific features of the phase formation dynamics in mechanically activated 16 wt% Al + Ti powder composition is described, the high-temperature synthesis being carried out under the condition of high volume inflammation by means of inductive heating. The kinetics of the phase formation were registered with an experimental complex, especially designed, constructed and adjusted for the method of dynamic diffraction analysis in synchrotron radiation beams. It has been experimentally in situ shown that increasing the time of mechanical activation of the initial powder mixture reduces the temperature at which components start to react and the time of realization of the high-temperature synthesis. With the latter set at 1 min of mechanical activation, the temperature of the reaction in the mixture is T = 603°C; at 3 min of mechanical activation, T = 442°C; and at 7 min, T = 359°C. The maximum burning temperatures are: for 1 min of mechanical activation, T max = 1080°C; for 3 min, T max = 1003°C; and for 7 min, T max = 820°C. It was found that formation of both stable compounds Ti3Al, TiAl3, TiAl2, TiAl and metastable phases Ti9Al23, Ti5Al11, Ti2Al5, Ti3Al5 occurs at the stage of primary structure formation, before the system goes to thermal explosion. High-temperature synthesis of a mixture of the studied composition takes place without formation of a liquid phase, in the solid-phase combustion mode. It was found that the increase in the time of mechanical activation of the initial powder mixture contributes to the formation of a product with a dominant content of intermetallic compound Ti3Al. By synthesis of the powder mixture of composition 16 wt% Al + Ti, mechanically activated for 7 min, the content of Ti3Al in the final product was found to be 68%.

scholarly journals Effect of Mechanical Activation on the In Situ Formation of TiB2 Particulates in the Powder Mixture of TiH2 and FeB

2017 ◽  
Vol 62 (2) ◽  
pp. 1393-1398 ◽  
Author(s):  
X.-K. Huynh ◽  
B.-W. Kim ◽  
J.S. Kim
Keyword(s):  
Mechanical Activation ◽  
Ball Milling ◽  
Powder Mixture ◽  
Electrical Power ◽  
Interface Reaction ◽  
High Energy ◽  
Decomposition Temperature ◽  
Homogeneous Microstructure ◽  
In Situ Formation

AbstractThe in situ formation of TiB2particulates via an interface reaction between Ti and FeB powders was studied. The effects of mechanical activation by high-energy milling on the decomposition of TiH2and the interface reactions between Ti and FeB powders to form TiB2were investigated. Powder mixtures were fabricated using planetary ball-milling under various milling conditions. The specific ball-milling energy was calculated from the measured electrical power consumption during milling process. High specific milling energy (152.6 kJ/g) resulted in a size reduction and homogeneous dispersion of constituent powders. This resulted in a decrease in the decomposition temperature of TiH2and an increase in the formation reaction of TiB2particulates in the Fe matrix, resulting in a homogeneous microstructure of nanoscale TiB2evenly distributed within the Fe matrix. In contrast, the powder mixture milled with low specific milling energy (36.5 kJ/g) showed an inhomogeneous microstructure composed of relatively large Fe-Fe2B particles surrounded by a thin layer of Fe-TiB2within a finely dispersed Fe-TiB2matrix region.

scholarly journals Influence of mechanical activation and heat treatment on magnetic properties of nanostructured mixture Ni85.8Fe10.6Cu2.2W1.4

2019 ◽  
Vol 55 (1) ◽  
pp. 85-93 ◽  
Author(s):  
M.M. Vasic ◽  
A.S. Kalezic-Glisovic ◽  
R. Milincic ◽  
Lj. Radovic ◽  
D.M. Minic ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Thermal Treatment ◽  
Mechanical Activation ◽  
Powder Mixture ◽  
Structural Characteristics ◽  
Volume Density ◽  
Magnetic Domains ◽  
Microstructural Changes ◽  
Mass Magnetization ◽  
Stress Relieving

The mechanical activation of the Ni85.8Fe10.6Cu2.2W1.4 powder mixture in the time intervals of 30-210 min in combination with thermal treatment at 393-873 K resulted in microstructural changes, forming the nanostructured mixture of the same composition but improved magnetic properties. The best result were achieved for mechanical activation during 120 min and thermal treatment at temperatures close to the Curie temperature (693K), enhancing the mass magnetization of the starting powder mixture by about 57%. The microstructural changes, which include the structural relaxation, decrease in free volume, density of dislocation and microstrain, improve structural characteristics of material, enabling better mobility of walls of magnetic domains and their better orientation in applied magnetic field and consequently enabling better mass magnetization of the material. With longer time of milling, the growing stress introduced in the sample undergoes easier relief, relocating stress-relieving processes toward lower temperatures.

scholarly journals Al-Ti-B4C materials obtained by high-temperature synthesis and used as a master-alloy for aluminum

2018 ◽  
Vol 243 ◽  
pp. 00010 ◽  
Author(s):  
Ilya Zhukov ◽  
Vladimir Promakhov ◽  
Yana Dubkova ◽  
Alexey Matveev ◽  
Mansur Ziatdinov ◽  
...  
Keyword(s):  
High Temperature ◽  
Burning Rate ◽  
Powder Mixture ◽  
Pure Aluminum ◽  
Al Alloy ◽  
Initial Powder ◽  
Temperature Synthesis ◽  
Al Content ◽  
High Temperature Synthesis ◽  
Al Powder

The paper presents microstructure, composition, and burning rate of Al alloy produced by high-temperature synthesis (SHS) from powder mixture Al-Ti-B4C with different concentration of Al powder. It has been established that the phase composition of materials obtained at gas-free combustion includes TiB2, Al, and TiC. It is shown that Al content growth powder in initial Al-Ti- B4C mixture from 7.5 to 40 wt.% reduces the burning rate of the powder from 9*10-3 to 1.8*10-3 m/s. For the system consisting of 60 wt.% of (Ti + B4C) and 40 wt.% of Al there is the increase in the porosity of the compacted initial powder mixture from 30 to 51 and reduction in the burning rate from 1.8 * 10-3 to 1 * 10-3 m/s. The introduction of 0.2 wt.% of the obtained SHS materials into the melt of pure aluminum causes reduction of the grain size of the resulting alloy from 1200 to 410 μm.

Compressive properties at elevated temperatures of porous aluminum processed by the spacer method

2005 ◽  
Vol 20 (12) ◽  
pp. 3385-3390 ◽  
Author(s):  
Masataka Hakamada ◽  
Tatsuho Nomura ◽  
Yasuo Yamada ◽  
Yasumasa Chino ◽  
Hiroyuki Hosokawa ◽  
...  
Keyword(s):  
Activation Energy ◽  
Relative Density ◽  
Stress Exponent ◽  
Elevated Temperatures ◽  
Chemical Compositions ◽  
Compressive Properties ◽  
Homogeneous Microstructure ◽  
Plateau Stress ◽  
Porous Aluminum

Compressive properties at 573–773 K of porous aluminum produced by the spacer method were investigated and compared with those of bulk reference aluminum with the same chemical compositions. The stress exponent and activation energy for deformation at elevated temperatures in the porous aluminum were in agreement with those in the bulk reference aluminum. In addition, the plateau stress of the porous aluminum was comparable to the stress of the bulk reference aluminum upon compensation by the relative density. Therefore, it is conclusively demonstrated that the mechanism of deformation at elevated temperatures in the porous aluminum is the same as that in the bulk reference aluminum. This is likely due to the homogeneous microstructure in the porous aluminum produced by the spacer method.

Manufacture of Al/SiC Composites by Pressure Infiltration Process

2005 ◽  
Vol 475-479 ◽  
pp. 913-916
Author(s):  
Fa Zhang Yin ◽  
Cheng Chang Jia ◽  
Xuezhen Mei ◽  
Bin Ye ◽  
Yanlei Ping ◽  
...  
Keyword(s):  
Relative Density ◽  
Process Parameters ◽  
Room Temperature ◽  
Sintering Process ◽  
Homogeneous Microstructure ◽  
Infiltration Process ◽  
Pressure Infiltration ◽  
Upper Limit ◽  
Thermal Debinding ◽  
Sic Composites

The SiCp performing sample was made first then Al/SiCp (65%) was manufactured. Appropriate component and proportion of binder and process parameters were selected to control the porosity. Debinding has succeeded by extractive and thermal debinding processes. SiCp preforming samples with good appearance, enough strength, and right porosity were obtained by pre-sintering process at 1100°C. Composites with high density and homogeneous microstructure were manufactured by pressure infiltration under 1050°C and 15MPa. The distribution of aluminium and silicon elements was homogeneous. The primary components of materials are aluminium, β-SiC and α-SiC. The thermal expand coefficient of composites is 8.0×10-6/°C at room temperature, which increases with temperature and reaches to 11.0×10-6/°C at 300°C. The density is 2.92g/cm3, and relative density is more than 97 %. The strength is about 500MPa, approaching to the upper limit of the theoretical value.

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