Papers by Keyword: hcp Metals

Abstract: This study combines nanoindentation experiments, electron backscatter diffraction (EBSD) and atomic force microscopy (AFM) topographic measurements to investigate the material anisotropy contribution to the indentation behaviour of individual grains of various hexagonal-close packed (HCP) polycrystals with different axial ratio (zinc, magnesium and titanium). The grain size was much larger than the indents size to ensure quasi-single-crystal indentation and when, combined with an EBSD mapping, a wide variety of crystal orientations can be probed, which provides mechanical characterization of materials at the micro/nanoscale. Experimental curves can be used to determine the mechanical properties of the indented material. Furthermore, by using data issued from AFM topographic measurements, one can analyze the dislocations arrangements below and around the indentation print, and thus characterize the most probably activated deformation systems.

Abstract: The ideal strengths of several hcp metals (Be, Mg, Ti, Zn, Y, Zr and Ru) have been investigated by first-principles stress–strain calculations. The results reveal that the ideal shear strengths of these hcp metals occur mainly on basal plane or prismatic plane. Particularly, for basal plane the peak shear stress in direction is smaller than that in direction. The calculated tensile strengths and elongations in direction are broadly consistent with the available theoretical results. Furthermore, both the ideal shear and tension strengths become stronger with the decreasing of c/a for these simple metals or transition metals. The calculated electronic structure further reveals the inherent mechanism of hcp metals.

Abstract: An end processing method of the pair-potential of modified analytical embedded atom method (MAEAM) was suggested for hcp metals with farther neighbor atoms. Through fitting the elastic constants, the cohesive energy and two equilibrium conditions of hcp metal crystals correctly, we changed the pair-potential parameters and the modification term parameters of the multi-body potential. The model calculations fully demonstrate the structure stability and the unrelaxed mono-vacancy properties of six hcp metals: Co, Mg, Re, Ru, Ti and Zr.

Abstract: Modelling the constitutive behaviour of metallic materials based on their microstructural features and the micromechanical mechanisms in the framework of continuum mechanics is addressed. Deformation at the lengthscale of grains is described by crystal plasticity. The macroscopic behaviour is obtained either by a homogenisation process yielding phenomenological equations or by a submodel technique. The modelling processes for two light-weight materials, namely magnesium and titanium aluminides are presented.