Influence of titanium and magnesium nanoinclusions on the strength of aluminum at high-rate tension: Molecular dynamics simulations
VV Pogorelko and AE Mayer, MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 662, 227-240 (2016).
With the use of the molecular dynamics simulations, by an example of Ti and Mg inclusions in Al matrix, we consider two different mechanisms of reduction of the tensile strength of a material with inclusions in comparison with a pure material of matrix. The first mechanism is connected with a stress concentration in matrix near a stiff and strong inclusion (Ti); in this case, the fracture occurs inside the matrix and does not touch the inclusion. The second mechanism acts in the case of a soft and weak inclusion (Mg); the fracture begins inside the inclusion and thereafter propagates into the matrix. The strength of the considered systems weakly depends on the orientation of crystal lattice of inclusions relative to the tension direction. The tensile strength of Al+Ti and Al+ Mg systems is determined at varied strain rates (in the range from 0.1/ns to30/ns at the temperature 300 K) and varied temperatures (in the range from 300 K to 900 K at the strain rate 1/ns). The rate sensitivity of strength of a material with inclusions is higher than that for a material without inclusions. Temperature dependences of tensile strength are qualitatively different for the systems Al+Ti and Al+ Mg; this fact is explained by the difference in the mechanisms of the material weakening. (C) 2016 Elsevier B.V. All rights reserved.
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