Elasticity and Debye temperature of defected fcc crystals (AlCu3, Al, Cu): Molecular dynamics and first-principles calculations

This paper deals with the effects of vacancies on physical properties of AlCu3 intermetallic crystal investigated by means of molecular dynamics (MD) and, independently, ab initio calculations. Moreover, our computer experiments were carried out for pure Al and Cu crystals for sake of comparison. In consequence, we determined how elastic characteristics and Debye temperature relate to the content of two types of vacancies arbitrarily introduced into the investigated crystals. We found a systematic decrease in elastic stiffness components (C-11, C-12 and C-44), bulk modulus, shear modulus, Young's modulus and Debye temperature, according to both Anderson's and Siethoff's models, and increase in Poisson's ratio with the growth of vacancy concentration. This holds for all the investigated materials approached by both MD and DFT-based methods. The computed values for the perfect crystals in the equilibrium state proved to agree with earlier literature data. We contend the results obtained for the defected structures are of importance for nanofabrication and provide valuable information on the nature of the materials of interest. (C) 2015 Elsevier B.V. All rights reserved.