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

The high specific strength of Ti-based alloys and composites makes them highly requested materials in various structural applications. However, reinforcement of the alloys with hard particles generally lowers the values of toughness and plasticity of material. A satisfactory combination of plastic and strength can be achieved by formation of layered structures comprising of two and more layers of different materials with different chemical compositions within individual layers. The multi-layer materials allow controlling the mechanical properties of the individual layers by changing microstructure and chemical composition within each layer specifically. In the present study, a cost-efficient process of fabrication of Ti-based multi-layer composites using blended elemental powder metallurgy (BEPM) and TiH2 powder is proposed. Two and three-layered composites based on titanium or Ti-6Al-4V alloy and their metal-matrix composites (MMC) with TiC and TiB were fabricated. Multi-layered samples reinforced by TiC were successfully sintered due to very close shrinkage of adjacent layers. Shrinkage values of layers reinforced by TiB were lower than those for the Ti-alloy, which led to delamination of layered structures, distortion of shape, and cracking. We can control shrinkage in individual layers by means of optimizing the powder size, that allows to obtain multi-layer titanium matrix composites reinforced by TiB with well-balanced mechanical properties.

Copper alloy-based metal matrix composite (MMCs) reinforced with different combination of WC-W powders were prepared using the spontaneous infiltration process of the loose powders. The density, microstructure, and hardness of the produced composites were characterized. Friction coefficient and wear rate of the samples under different conditions were carried out in order to determine the tribological properties of the copper based composites as a function of different combination of reinforcement mixtures (WC/WC-W). Wear surfaces of the composites were analysed by scanning electron microscopy (SEM). Results show that WC-W powders improve wear resistance of composites significantly. Wear mechanisms were characterized by delamination, micro cracking and abrasive wear.

Review of pulses discharge technologies (PDT), in which pulses electric discharge in liquid is utilized, is given. PDT of processing and obtainment of new materials allows to impact both changes of geometrical size and the structure of objects in order to give it certain mechanical and physical properties. They are used in oil production, instrumentation, mechanical engineering, metallurgy, chemical industry, mining complex, and other.

Development of new alloys has been slowed by the empirical method of trials and errors that absorbs more and more resources and leads to ever smaller results. Solution of this problem is possible through the use of the general principles of the alloys design theory. In this paper, we have proposed to consider cast metal matrix composites as foundry alloys and have developed a methodological approach to selection of alloying and reinforcing components considering the operational conditions for parts of friction units. Application of the proposed approach allows to make reasonable choice of composite alloys components within conditions of various schemes of reinforcing, including exogenously reinforced, endogenously reinforced and complex reinforced alloys.