International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

This study investigates the influence of Al₂ O₃ content on the mechanical properties of sintered Al-10Cu-xAl₂ O₃ (x = 2.5, 5, and 7.5 wt.%) composite materials, produced via powder metallurgy and subjected to quasi-static and dynamic compressive loadings. Quasistatic tests were performed at a constant strain rate of 0.003 s⁻ ¹, while dynamic tests were conducted at strain rates corresponding to impact velocities of approximately 10 m/s and 20 m/s. The results indicate that a higher Al₂ O₃ content enhances the mechanical properties of the composite under both quasi-static and dynamic compression. The most significant improvements were observed under high strain rate impact loading, highlighting the potential of sintered Al-10Cu-xAl₂ O₃ for applications in dynamic environments.

This study investigates the mechanical behaviour of Al10Cu materials fabricated through powder metallurgy and subjected to quasi-static and dynamic compressive loadings. The materials were sintered and tested under controlled conditions to evaluate their compressive strength. Quasi-static tests were performed at a constant strain rate of 0.003 s⁻ ¹, while dynamic tests were conducted at strain rates corresponding to impact speeds of about 10 m/s and 20 m/s. The results indicate that sintered Al10Cu materials are suitable for applications under high-strain impact loadings due to their high energy absorption. These findings highlight the potential of powdermetallurgy-derived Al10Cu alloys for applications requiring high strain rate performance, offering insight into their suitability for use in dynamic environments.

Studies of the impact of high voltage electric discharge (HVED) treatment on the dispersion and phase composition of 87,5 % Al + 12,5 % Cu powder system were performed. It was shown that HVED treatment in ethanol with specific treatment energy of 5 MJ/kg leads to the decrease of mean diameter of treated powder from 15 to 11 μm, and the increase of specific treatment energy to 20 MJ/kg leads to the decrease of mean diameter of treated powder from 15 to 6 μm. X-ray diffraction analysis shows that CuAl2 and Al4C3 are synthesized in all considered treatment regimes, and the quantity of these phases depend on the specific treatment energy.
The use of “three point – plane” electrode system instead of “point – plane” during HVED treatment of 87,5 % Al + 12,5 % Cu powder system in ethanol leads to the increase of quantity of synthesized Al4C3 and CuAl2 phases with the slight decrease in the dispersion efficiency.
Up to 35% of particles in powder mixture, treated by HVED in ethanol with the use of “three point – plane” electrode system, have diameter close to the diameter of the initial powder mixture.
It is shown that the preparation of powders with an initial composition of 87.5% Al + 12.5% Cu using HVED treatment in kerosene or ethanol with subsequent consolidation by SPS method allows obtaining metal-matrix composites of the Al – Cu – C system with increased indicators of hardness, electrical conductivity and wear resistance.

Currently, metallic materials featuring a porous structure are extensively employed in passive safety mechanisms for absorbing mechanical energy during dynamic loads. Among these, aluminum foam-based damping materials are the most prevalent due to their adequate processability and cost-effectiveness. Nonetheless, expanding the array of properties within damping materials necessitates exploring the utilization of porous titanium-based products, known for possessing exceptional specific strength metrics. This avenue emerges as one of the most promising ways for advancing the domain of damping and energy-absorbing materials.

Studies of the impact of high voltage electric discharge (HVED) treatment on the dispersion and phase composition of 87,5 % Al + 12,5 % Cu powder system were performed. It was shown that HVED treatment in kerosene with specific treatment energy of 5 MJ/kg leads to the decrease of mean diameter of treated powder from 15 to 13 μm, and the increase of specific treatment energy leads to the decrease of mean diameter of treated powder from 15 to 6 μm. X-ray diffraction analysis shows that CuAl2 and Al4C3 are synthesized in all considered treatment regimes.
HVED treatment with increased specific treatment energy leads to the increase of quantity of synthesized Al4C3 phase. The use of “three point – plane” electrode system instead of “point – plane” during HVED treatment of 87,5 % Al + 12,5 % Cu powder system leads to the increase of quantity of synthesized Al4C3 and CuAl2 phases, while the efficiency of powders dispersion slightly decreases. Up to 40% of particles in powder mixture, treated by HVED in kerosene with the use of “three point – plane” electrode system, have diameter close to the diameter of the initial powder mixture

The peculiarities of the structure and phase composition of the high-entropy alloy of the TiCrFeMnSiC system obtained from the powder mixture of ferrotitanium, ferrochrome and ferrosilicon-manganese ferroalloys are considered in the work. The technological scheme of alloy production included joint grinding of the mixture in a planetary mill, consolidation of the blanks, their heating to 1100 0C, hot forging on the arc press and subsequent annealing of hot-forged samples at 1200 0C. According to the results of X-ray analysis of the obtained alloy, it was found that the main phase of the alloy is the BCC phase with the parameter of the cubic lattice a = 0.2868 nm, which is a solid solution based on alloying components of the original charge. The phase composition of the composite also recorded ti tanium carbide TiC with FCC lattice with the parameter a = 0.4319 nm, which corresponds to a stoichiometric composition of about TiC0.6 and a small amount of FCC phase of iron-chromium carbide (Cr, Fe)23C6 with lattice parameter a = 1.0645 nm. The material has a high hardness (up to 60-61 HRC), which can provide high resistance of this multicomponent alloy.

Iron powder metallurgy is a method that is widely used in production of steel parts that are utilized as machine components or as parts in automotive industry. Milling is extensively used in powder metallurgy of iron, for purposes of mixing. The hardness and yield strength of milled iron powders increase due to work hardening. This leads to low green density of the cold pressed green parts, prior to sintering. In powder metallurgy, warm compaction is utilized for enhancing the green density and green strength.
In the present study, effect of warm compaction of milled iron powders was investigated. For warm compaction of iron powders, 600 MPa pressure was applied in a steel die at 150 oC. The microstructure of the milled samples was examined by scanning electron microscopy. Hardness values of the cold pressed and warm compacted samples were determined by a Brinell hardness tester. Bending strength values of the samples were determined by a universal testing machine. It was found that the hardness of the cold compacted green samples increased considerably, from about 40 Brinell10 to about 140 Brinell10, as a result of warm compaction. Bending strength values increased to over 100 MPa after warm compaction; whereas the bending strength of the cold compacted green samples were in 10-20 MPa range.

Titanium diboride reinforced iron matrix composites were produced via powder metallurgy techniques. Iron powder (<10 microns) and titanium diboride powder (<10 microns) were mixed in a ball mill and the powder mixture was cold compacted in a steel die at 550 MPa pressure. Amount of titanium diboride that was added into iron was in 3-10 wt %. Sintering was performed at 1120 oC for 30 minutes in argon atmosphere. Sintered samples were subjected to three-point bending tests, hardness measurements and microstructural examinations.
It was found that the hardness of the composites increases significantly with the increase in the amount of titanium diboride addition. Hardness of unreinforced iron was 50 Brinell 10 and that of 10 % titanium diboride reinforced composite increased to 100 Brinell 10. On the other hand, there was a decrease in the bending strength and strain of the composites, with increasing titanium diboride addition. Bending strength of unreinforced iron was 850 MPa and that of 10 % titanium diboride reinforced composite decreased to 350 MPa.

The main characteristic of the powder metallurgical materials that distinguishes them from the summer ones is the presence in them of residual porosity. For this reason, the processes of their thermochemical treatment are differ significantly from those occurring at saturation of dense ones. In the present paper the impact of technological processes such as boronizing, chromizing, siliconizing, carburizing, borocarburizing, etc., is monitored on the kinetics of diffusion layer growth in powder materials with a porosity of 5÷35%. The specimens of iron powders NC 100.24 and those doped with 2% Cu were subjected to study. The samples were pressed with an effort of 200 ÷ 800MPa and sintered for 0.5h at 1150°C in dissociated NH3 medium. Thermochemical treatment was conducted at 950°C for 4 hours in semi-permeable saturation media. Graphical dependencies for varying the thickness of diffusion coatings in different thermochemical treatment modes are presented, depending on the porosity of the saturation materials.

The possibility of control of efficiency of different factors of high voltage electric discharge (HVED) impact on Ti – Al – С powders system for aimed synthesis of dispersion-hardening components is shown. Nanolaminate-composite Ti₃AlC₂ – TiC with hardness of HV5 = 7 GPa, obtained by consolidation of blend of 85 % Ti + 15 % Al initial composition after HVED with the use of multi-point electrode system has needle structure of Ti₃AlC₂ (a = 0.3068 nm, c = 1.844 nm) with size up to 10 μm, and TiC dispersion-hardening phase (a = c = 4.4331 nm) with particle size no more than 1 μm is situated between grains of Ti₃AlC₂. Dynamic strength of specimens depending on electrode system used during HVED treatment of blend variated in range from 160 to 620 MPa, Young modulus – from 13 to 22 GPa at deformation rate from 600 to 900 s–1. Material has high levels of heat resistance, relative change of mass is no more, than 0.001.

As a result of sintering the powder workpieces large part of the separated free energy leads to higher density of sintered body. This in turn is accompanied by a change in linear dimensions of workpieces. These linear changes in addition to the alloying elements in iron matrices largely depend on the technological parameters of the sintering process – temperature, duration, protective atmosphere and others. This study monitored the impact of the type of protective atmosphere and duration of sintering on the size change of powder workpieces of iron powder ASC 100.29 alloyed 0,15 ÷ 0,60% P. Sintering is conducted at 1150ºC a duration of 15 ÷ 90min in two protective environments – endothermic gas and dissociated ammonia. Presented are graphical relationships of the relative change in the diametric dimensions of the workpieces in dependence on the concentration of phosphorus in them, the type of the protective atmosphere and the duration of sintering.

Changes of dispersity, form factor and phase composition of powder mixtures of 75% Ti + 25% Al, 50% Ti + 50% Al, and 25% Ti + 75% Al mass compositions after treatment by high voltage electric discharge in kerosene are experimentally studied. Regularities of their dispersion and synthesis of TiC, AlTi₃, AlTi, Al₂Ti, Al₃Ti, double carbide Ti₃AlC, МАХ-phases Ti₃AlC₂ and Ti₂AlC, Lonsdaleite are found.