A new method for producing high-hardness metal matrix composites has been developed.

The research was supported by a grant from the Russian Science Foundation. The results of the study were published in the journal Ceramics International (Q1, IF: 5.1).

Aluminum matrix composites, due to the combination of metal and ceramic properties, are currently regarded as advanced materials for numerous automotive and aerospace applications, such as brake discs, drums, and pistons, as well as wings and fuselages. They exhibit excellent plasticity, corrosion resistance, high stiffness, strength, and the potential for recyclability. However, all conventional ex-situ approaches to producing such compositions lead to a reduction in the physical and mechanical properties of bulk samples.

Scientists from Tomsk Polytechnic University have proposed a unified strategy for obtaining aluminum matrix composites with enhanced properties—from a unique method for producing in-situ composite powders to their consolidation and physical-mechanical testing.

The researchers' approach is based on the "embedding" of reinforcing tungsten, silicon, and boron carbide particles into a metallic matrix using plasma dynamic synthesis.

“The uniqueness of our approach to creating dispersed composites lies in the fact that the introduction of reinforcing particles into the metallic matrix occurs as a result of the interaction of components during the processing with impulse plasma from an arc discharge. This method is based on the in-situ approach, where the formation of the reinforcing component and the metallic matrix, as well as their combination, take place in a single process.

In contrast to traditional ex-situ methods, this ensures a uniform distribution of micro- and nanoscale carbide particles in the product and their incorporation into the aluminum matrix, good interfacial bonding, as well as a polymodal particle size distribution, ultimately enhancing the physical and mechanical properties of the final products,” notes one of the study's authors, Dmitry Nikitin, an associate professor in the Department of Power Engineering and Electrical Engineering at TPU.

According to the scientists, the carbide phase content in the finished composite can vary from 5.85% to 16.38% depending on the initial process conditions. This will allow for "tuning" the characteristics of the composites.

By adding carbides to the composite during the production of bulk samples, the material acquires a unique structure. For instance, this allows achieving a high degree of compaction of all components (up to 99%) and improved physical-mechanical properties. The results of the study show that the new composites developed by TPU researchers are up to four times harder than their counterparts: they reach hardness in the range of 103-215 HV, whereas similar samples made from commercially available components show hardness levels of 47-62 HV.

“It is important to note that the proposed in-situ method of combining aluminum matrix material with ceramic carbide does not lead to the formation of porous samples and recrystallization of particles, which often complicates the production of quality composites. This means that the final products will exhibit significantly improved mechanical properties and wear resistance,” adds Dmitry Nikitin.

The results of the research could serve as a basis for the development of highly efficient composite materials for aviation, automotive, and other industries where materials with low specific mass and increased hardness are required.