Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 6: Mechanical Properties II

MM 6.4: Vortrag

Montag, 26. März 2012, 12:15–12:30, H 0106

ab initio study of the mechanical shear behavior of Al with and without normal stresses — •Xueyong Pang, Rebecca Janisch, and Alexander Hartmaier — ICAMS, Bochum, Germany

To investigate the mechanical shear properties of interfaces in metals we have determined the gamma-surfaces of different special tilt and twist grain boundaries in aluminum by means of ab-initio calculations. From the gamma-surfaces we obtained minimum energy paths and barriers, as well as the theoretical shear strength. For the [110] tilt grain boundaries, the theoretical shear strength scales with the height of the slip barrier and exhibits a relation with the misorientation angle: the closer the angle to 90°, the higher the shear stress. To estimate the effect of full atomic relaxation, we carried calculations of the theoretical shear strength of Al single crystals in the (111) plane by different deformation methods. To investigate the influence of normal stresses on the shear behavior of Al, we also performed a series of combined normal/shear calculations on single crystal Al and grain boundaries. The critical shear strength follows the linear relationship with the normal stress; the critical shear strength decreases with the compression stress decreases and the tensile stress increases.