Materials Science. Non-Equilibrium Phase Transformations.
Vol. 7 (2021), Issue 1

Table of Contents

  • Structure and properties of chromium carbide reinforced steel matrix composites produced from powder iron-ferrochrome mixtures

    pg(s) 3-5

    The influence of high-carbon ferrochrome on the features of structure formation and properties of chromium carbide steels based on the Fe-FKh800 system was investigated. It was shown that the optimal combination of hardness and tensile strength with sufficient crack resistance has a carbide base of 65% Fe – 35% (wt.) FKh800. A typical microstructure of sintered carbide is a metal matrix composite consisting of chromium steel of composition close to Kh17 and double carbide (Cr0.799Fe0,201) 7C3. The effect of TiB2 additive on the structure, phase composition, mechanical and tribotechnical properties of materials based on the Fe- 35 (%,wt.) FKh800 system was also investigated. Additions of titanium borides in the amount of 0.38-1.48 (% wt.) leads to some increase in hardness, noticeable increase in the flexural strength and leads to increase wear resistance of carbidosteels.

  • Phase transformations in non-metallic inclusions under laser action

    pg(s) 6-10

    It was found that in the process of pulsed laser action, various phase and structural transformations occur in non -metallic inclusions, which take place under nonequilibrium conditions. It is shown that the melting of inclusions under laser action is corresponded with change of their structure and phase composition. Also it is shown that the nature of these transformations depends on the type of nonmetallic inclusion. It was found that nonequilibrium phase transformations contribute to a change in the structure, phase composition, properties and sizes of nonmetallic inclusions, as well as the inclusion-matrix interphase boundaries of steel. It is shown that changes in the structure and properties of non-metallic inclusions affect their behavior and the formation of defects in the laser-strengthened layer of steel
    products.

  • Structure transformation in graphite at high-energy ball milling treatment

    pg(s) 11-13

    The changes in the structure of the crystalline graphite are studied during high-energy ball milling (BM) treatment. It was found by XRD analysis the milling time increasing up to 3.5 h leads to the formation of an amorphous phase in the milling process. After 10 h of ball milling treatment, complete amorphization of graphite takes place. It has been shown by high-resolution electron microscopy the individual particles have complex morphology which depends on the BM time. After 1 h of BM carbon materials characterized by an onion-like structure: the individual particles have a spheroidal shape with a size of ~ 10 nm. However, unlike the previous ones after 10 h of ball milling carbon nanomaterials are characterized by a disordered structure, which is typical for amorphous carbon.

  • Martensitic transformation and magnetic ordering in as-cast Fe-Mn-Si-Ge and Fe-Mn-Si- Sn alloys

    pg(s) 14-18

    Crystal structure, morphology, peculiarities of martensitic transformation and shape memory effect were investigated in Fe-Mn-(Si,Ge) and Fe-Mn-(Si,Sn) as-cast alloys. It was found that regularly substitution of atoms Si with the Ge or Sn in Fe-Mn-Si alloys dramatically change the martensitic transformation behavior that displayed in calorimetry, resistometry and dilatometry curves during the cooling and heating the alloys. Crystal structure changed as well. As a result of alloying by Ge and Sn the substructure of samples became more inhomogeneous, well developed dendritic structure appeared, finally (Mn0.5Fe0.5)3Sn2 phase and hexagonal phase with the structure 63/ have precipitated in Fe-Mn-(Si,Sn) and Fe-Mn-(Si,Ge) respectively. The effect of alloying with Si or Ge on γ→ε temperatures of martensitic transformation, volume effect of transformation, Neel point caused by the influences of alloying components as well as the ferromagnetic phases appearing during as-cast process.

  • Features of electromechanical properties of carbon nanostructures

    pg(s) 19-20

    Non-standart properties of carbon nanomaterials and nanostructures open wide possibilities of their application. The electrical resistance of bulk arrays of carbon nanotubes in cyclic loading-unloading processes was studied. It is shown that when the volume of the powder sample decreases, the resistance first decreases sharply, and at a certain degree of compression the process of its chang e begins to occur more smoothly, which is associated with increased contacts between neighboring nanostructures and van der Waals bond between them.

  • Development of new composite electrotechnical materials with advanced characteristics for application in novel equipments

    pg(s) 21-22

    An urgent task for the electrical industry is to develop new soft magnetic materials, in particular composites. The greatest interest present composites in which filling components have metal-dielectric-metal (MDM) interaction. Recent few years many research centres are carry out intensive developments of soft magnetic composites (SMC) based on use of soft magnetic particles, usually based on iron, with an electrically insulating coating on each particle. The carried out preliminary researches of a composite magnetic material based on iron ASC 100.29 and Atomet 1001HP powders, surface of which is capsulated by ferrite, have shown perspectives of their application in engineering. Unique specific parameters of a softmagnetic composite material – a magnetic induction of saturation 2.1 Tesla, work in a frequency range up to 100 kHz at Curie temperature from above 800°C allow to use it in high speed valve and valve-jet electromachines and as chokes and high-frequency transformers.

  • Phase transformations in high-entropy FeNiCoCrAl alloys during oxidation

    pg(s) 23-26

    The evolution of phase composition and mechanical properties and the formation of oxide layers on Fe40–xNiCoCrAlx (x = 5 and 10 at.%) alloys in long-term oxidation at 900 and 1000 °C were studied. In the initial cast state, depending on the aluminum content and valence electron concentration, the alloys contain only an fcc solid solution (VEC = 8 e/a) or a mixture of fcc and bcc phases (VEC = 7.75 e/a). Thin continuous oxide scales containing Cr2O3 and NiCr2O4 spinel formed on the surface of both alloys oxidized at 900°C for 50 h. A further increase in the annealing time to 100 h leads to the formation of aluminum oxide Al2O3 in the scale on the Fe30Ni25Co15Cr20Al10 alloy, having high protective properties. An increase in the oxidation temperature to 1000°C results in partial failure of the protective layer on the
    alloy with 10 at.% Al. Long-term holding at 900°C (100 h) + 1000°C (50 h) does not change the phase composition of the Fe35Ni25Co15Cr20Al5 alloy matrix, being indicative of its high thermal stability. In the two-phase Fe30Ni25Co15Cr20Al10 alloy, the quantitative ratio of solid solutions sharply changes: the amount of the bcc phase increases from 4 to 54 wt.% and its B2-type ordering is observed. The mechanical characteristics of the starting alloys and those after long-term high-temperature annealing were determined by automated indentation. It is shown how the hardness (HIT) and the elastic modulus (E) of alloys change after oxidation, depending on the Al content.

  • Structure studding of recycling rubber materials through Infrared with ATR, DSC and Scanning electron Microscopy and energy dispersive analysis (SEM)

    pg(s) 27-30

    Tires are complex objects that consist of many different parts, each with a specific formulation, and include natural or synthetic polymers, carbon black, steel, dispersed oils, dispersed oils, sulfur for the vulcanization or bonding process, organic addit ives and inorganic, and even glass fibers. Their investigation poses a difficulty in identifying them, due to their complex structure. In the Tire
    Recycling Industry we encounter the problem of quality control, which is difficult due to the lack of solubil ity of rubber particles, as well as the limited technical means of these industries. The study aimed to investigate the structure and composition of recycled tires, used in artificial turf / grass as fillers.
    The study focused on the development of standard investigation methods using three instrumental and analytical techniques, as well as the study of morphological changes they have undergone during the recycling process and the impact of additives on them. The aim of this scientific search is studying the structure rubber these materials are recycled, that is one of the most important issues, especially in Albani. Through FT-IR with ATR Analysis, is a analysis technique that provides information about the chemical bonding or molecular structure of materials, Differential Calorimetry DSC and Scanning Electronic microscope (SEM) equipped with the system of
    dispersive of energy spectroscopy (EDS).

  • Knowledge for material science. Part I

    pg(s) 31-39

    This article discusses the modern knowledge necessary for materials science. Modern scientific knowledge covers on the basis of the greatest scientific results; complete scientific knowledge: mathematics; mathematical physics; quantum mechanics (not relativistic and relativistic); quantum physics; quantum chemistry. Theory and modern tools for testing and monitoring with increasing resolution. High technologies. A research – type methodology has been obtained, but this methodology is also focused on interactions with business. Business research is not fundamental, but it can be very lengthy.

  • Habits of nanocrystals of cubic and hexagonal systems

    pg(s) 40-41

    habits of coordinational polyhedras are considered as forms of nanocrystals. Habits for coordination polyhedra with numbers from 1 to 30 are given. It was analazide the cubic and hexagonal lattices. There are the next nanocrystals: primitive, cubic and intercentered and face-centered and diamond-like (all cubic) and hexagonal close packed.