Modern materials science is characterized by a growing interest in hybrid composite materials that combine the advantages of various reinforcing phases to achieve improved mechanical properties. This work is devoted to the study of the microstructure and mechanical characteristics of a hybrid composite based on an aluminum matrix reinforced with boron carbide (B₄C) and Al-Cu-Fe quasicrystals. The aim of the study is to identify the synergistic effect of the combined introduction of these two types of reinforcing phases into an aluminum matrix.
The process of obtaining the composite included powder metallurgy followed by hot pressing. The initial powders of aluminum, boron carbide and quasicrystalline Al-Cu-Fe alloy were thoroughly mixed, compacted and sintered at elevated temperature under pressure. Microstructural analysis was carried out using optical and electron microscopy, including scanning electron microscopy (SEM) and transmission electron microscopy (TEM). X-ray diffraction analysis (XRD) was used to identify the phase composition of the composite.
In order to analyze the combined effect of reinforcing components on the structure and mechanical properties of composite materials, hybrid aluminum composites were created, including boron carbide particles and quasicrystals. Each type of particle was introduced in an amount of 6% of the total mass, which in total amounted to 12% reinforcement in the aluminum base. For comparison, two composites, each with 12% content of one type of reinforcing particles, and a reference sample of pure aluminum were also produced. The ball milling method was used to homogenize the composite components. The subsequent production of composite powder samples was carried out by uniaxial pressing at room temperature and consolidated by sintering without applying pressure in a protective environment. Microstructure analysis was carried out using scanning electron microscopy, and phase analysis was carried out using X-ray diffraction. Mechanical properties were evaluated by measuring Vickers hardness and compression tests. Hybrid composites showed improved compressive properties, while composites containing only quasicrystals showed increased hardness. The improved mechanical properties are attributed to changes in the microstructure caused by the presence and uniform distribution of the binary particles.
The mechanical properties were assessed by microhardness, compression and bending tests. Microhardness was measured using the Vickers method under various loads. Compression and bending tests were conducted in accordance with established standards. The results showed that the addition of boron carbide and Al-Cu-Fe quasicrystals leads to a significant increase in the strength and hardness of the aluminum matrix. A synergistic effect is observed, whereby the combined introduction of these phases yields higher mechanical properties than when using each phase separately.
Microstructure analysis showed uniform distribution of reinforcing phases in the aluminum matrix. Good adhesion between the matrix and reinforcing particles was observed. The strengthening mechanism is explained by precipitation hardening, as well as the Orowan mechanism, which prevents the movement of dislocations. The results obtained demonstrate the prospects for the development of hybrid composite materials for a wide range of applications.
Author: Mahmood Khan, Muhammad Zulfaqar, Fahad Ali, Tayyab Subhani
Institute: Materials Processing Group, Pakistan Institute of Engineering and Applied Sciences, Islamabad, 44000, Pakistan