The structure and mechanical properties of composites consisting of a metal matrix based on aluminum and its alloys of different compositions (AA-3003 and AA-5154) and graphene synthes sized in situ under a layer of molten salts were investigated depending on the chemical composition and grain size of the matrix. Aluminum matrix composites of three compositions were studied in as-cast coarse-grained, deformed fine-grained (grain size < 1 mm), and deformed sub microcrystalline (grain size < 1 μm) states in order to compare the structural characteristics of composites with different grain sizes. The composites were subjected to deformation with a split Hopkinson (Kolsky) bar and to dynamic-channel angular pressing. The hardness and dynamic mechanical properties of the composites were measured at strain rates $\dot{\epsilon }$ from 1.8 − 4.7 × 10³ to 1.6 − 2.4 × 10⁵ s⁻¹. It was found that grain refinement induced a sharp increase in the hardness of composites with various compositions (by a factor of 1.6–2.6). A correlation of the elastic-plastic properties of the aluminum matrix composites with the grain sizes and chemical compositions of the matrices was established. A transition from coarse-grained to sub microcrystalline structure was shown to improve the elastic-plastic properties on average by a factor of 1.5. It was proved that the reinforcing effect of graphene increased with the decreasing grain size of the matrix. Mechanisms of reinforcement of the aluminum matrix composites using graphene were proposed.

A comparative study of the deformation behavior of submicrocrystalline (formed by dynamic channel angular pressing) and coarse-grained commercial aluminum alloys (AMts and V95), and commercial aluminum A7 has been performed under impact compression conditions. Dynamic elastic limit (Hugoniot elastic limit) σ_HEL, yield strength Y, and spall strength σ_sp at a deformation rate of (1.2–3) × 10⁵ s⁻¹ were determined by analyzing the experimental velocity profiles of the free surface of samples. It has been found that the dynamic elastic limit and yield strength increase after all the materials studied have transformed into a submicrocrystalline state (crystallite size of 200–700 nm). Submicrocrystalline alloy V95 has the highest value of Y and submicrocrystalline aluminum A7 has the lowest one. The effect of grain size on spall strength is ambiguous. The values of σ_sp for submicrocrystalline alloys are 1.32–1.36 GPa. The submicrocrystalline V95 alloy and commercial A7 aluminum demonstrate a decrease in the spall strength, whereas the spall strength of the alloy AMts slightly increases with decreasing grain size.