Methods for introducing carbon into the composition of structural powder materials

Durability and reliability of machines and mechanisms depends on the structural strength of the products from which they are made. The main requirement for any product is trouble-free operation under the conditions of the established operational period. This determines the requirements for structural materials, the main of which are technological, operational and economic. The production of sintered powder products ensures the lowest energy consumption and the lowest waste. The introduction of carbon into powder materials significantly increases the strength characteristics of the product.

On some prospects for further development of Academician V.N. Antsiferov ideas in the field of structural powder materials

The paper discusses the further development of some ideas of V.N. Antsiferov and the scholar school created by him in obtaining structural powder materials and products. The prospects for obtaining concentration-inhomogeneous steels and trip-steels are noted. The great potential lies in the control of the thickness and volume of the zone of deformation martensitic transformation occurring during fracture. It is advisable to continue the preparation of fullerene- and nitrogen-containing powder compositions and to study the structural heredity of powder steels. The possibility of the synthesis of fullerene-containing phases during the liquidphase sintering of the iron–cast iron and iron–graphite compositions and their subsequent redistribution in the bulk of the material during dynamic hot pressing is worth noticing. Producing nitrogen-containing steels by mechanical activation of powders followed by sintering in dissociated ammonia is advisable to use for obtaining not only wear-and corrosion-resistant materials, but also heat-resistant ones. The studies on the decomposition of supercooled austenite in powder steels of various doping systems with different technological backgroung (sintered, hot-deformed, infiltrated, etc.) are promising. The potential for development is the research of hot-deformed concentration-inhomogeneous materials, obtained, in particular, on the basis of powders of the Distaloy type. The techniques developed by the Antsiferov’s school are significant. The most important one is the method for determining the concentration variation coefficient, as well as a magnetometric complex and a mathematical model, which makes it possible to predict the decomposition of supercooled austenite. Antsiferov’s works can be used for obtaining lean powder steels with the lower bainite structure, which provides the optimal combination of strength and toughness.

The effect of structural changes during sintering on the electric and magnetic traits of the Ni96.7Mo3.3 alloy nanostructured powder

Ni96.7Mo3.3 powder was electrochemically obtained. An X-ray diffraction analysis determined that the powder consisted of a 20% amorphous and 80% crystalline phase. The crystalline phase consisted of a nanocrystalline solid nickel and molybdenum solution with a face-centred cubic (FCC) lattice with a high density of chaotically distributed dislocations and high microstrain value. The scanning electronic microscopy (SEM) showed that two particle structures were formed: larger cauliflower-like particles and smaller dendriteshaped ones. The thermal stability of the alloy was examined by differential scanning calorimetry (DSC) and by measuring the temperature dependence of the electrical resistivity and magnetic permeability. Structural powder relaxation was carried out in the temperature range of 450 K to 560 K causing considerable changes in the electrical resistivity and magnetic permeability. Upon structural relaxation, the magnetic permeability of the cooled alloy was about 80% higher than the magnetic permeability of the fresh powder. The crystallisation of the amorphous portion of the powder and crystalline grain increase occurred in the 630 K to 900 K temperature interval. Upon crystallisation of the amorphous phase and crystalline grain increase, the powder had about 50% lower magnetic permeability than the fresh powder and 3.6 times lower permeability than the powder where only structural relaxation took place.