PSI - Issue 65

E.G. Zemtsova et al. / Procedia Structural Integrity 65 (2024) 317–323 E.G. Zemtsova et al. / Structural Integrity Procedia 00 (2024) 000–000

318 2

1. Introduction

Civil engineering, transport (Lymar et al. (2014)), aviation and rocket technology, the oil and gas industry, electrical engineering, consumer goods and the food industry are far from a complete list of aluminum applications (Lymar et al. (2014), Zhilyaev et al. (2007), Kumar et al. (2021), Edited by Hatsh (1984)). A special place in mechanical engineering is occupied by cast Al and its alloys. This is the basis of the entire Al industry. One of the important tasks of modern materials science is the development of new composite materials with improved functional properties (Lymar et al. (2014)). Increasing the strength of metal materials by traditional methods (increasing the content of alloying elements, improving thermomechanical hardening technologies, etc.) has now exhausted its possibilities. A significant increase in the number of alloying elements in alloys (high-entropy alloys) leads to zonal and volumetric liquation in ingots and, as a result, to anisotropy of the properties of semi finished products and parts made of them. The analysis of the conditions for obtaining KM by injection molding (the introduction of reinforcing fillers) revealed a number of problems that need to be solved to obtain a material with improved properties: the need to ensure good wettability of the hardener (dispersed phase) by matrix melt; the possibility of interaction processes between KM components; ensuring uniform distribution of reinforcing filler. Additional alloying fillers are included in aluminum alloys in quantities from several tenths to one percent and enhance (complement) the basic properties of the alloy or give it new (special) properties. In most cases, they can be considered as improving additives, since they are often introduced to improve technological properties. Additives (dispersed particles) introduced into the alloy inhibit the movement of dislocations, therefore, along with the bulk concentration of particles, particle size and the distance between them become important. The most effective hardening is achieved when the particle size of the hardening phase is 0.01-0.05 microns and the distances between them are 0.1-0.5 microns. Further exposure of alloys at elevated temperatures leads to coagulation (enlargement) of dispersed particles, a decrease in strength and an increase in the ductility of alloys. The possibility of additional alloying additives to influence the strength characteristics of alloys is due to: additional hardening due to entering into a solid solution; grinding of the structure (grains or iron-containing phases); increased heat resistance due to the creation of inclusions of solid, thermally stable intermetallics along the grain boundaries. Most structural Al alloys have been created on the basis of injection hardening. These materials are the basis for the creation of more complex systems, with additional approaches in hardening: additive hardening, heat treatment hardening (Agarwal et al. (2011)), composite hardening (Tham et al. (2001), Rino et al. (2012)). It should be noted that due to the alloying of a solid solution (cast Al), relatively small distortions of the crystal lattice are achieved, therefore, the strength gain is small and does not exceed 10-30% of the base strength, but the plasticity remains at a fairly high level. The alloy strength is mainly influenced by the grain size of the matrix and this mechanism is well described by the Hall-Petch ratio. It is known that during recrystallization of the melt, the presence of nanoscale particles in the matrix bulk changes the grain size of the matrix itself. This approach makes it advantageous to use solid solutions as the basis of structural materials when creating alloys that are easily subjected to plastic deformations. The creation of alloys with increased strength characteristics, where strength is considered as resistance to plastic deformation under constant loads, is one of the very first directions of alloying (reinforcing) Al. Despite this, work in this direction has not stopped until now (Zemtsova et al. (2021)). It is necessary to find a synthetic approach to solve the problem of aggregation and sedimentation of the reinforcing filler, to find an opportunity to influence the wetting process. As a result of our research, an approach was proposed to obtain a metal matrix composite material using the process of surface structuring of the reinforcing phase. The developed approach made it possible to obtain a composite material where TiC nanostructures up to 4 nm in size are evenly distributed in the aluminum matrix bulk. The particle size of TiC in cast Al is equal to the thickness of the carbide nanolayer chemically bonded to the matrix particles. This approach allows not only to increase the strength properties of the composite material, but also to preserve plasticity.