The variation in microstructural response with the orientation of loading allows for a wide range for tailoring mechanical properties of pure magnesium single crystals without any need of alloying. The microstructure studies by electron backscatter diffraction and XRD pole figure analysis revealed profuse ( $10\overline12$) twinning when compression is done along the growth plane (72 16 $\overline $ 15) was marked by a much lower degree of both twinning and recrystallization. Compressive testing along two orthogonal directions at low plastic strains was also performed. It was found by impact testing that the magnesium single crystal is highly ductile due to energy absorption by twinning and slip, while the polycrystalline samples fracture easily upon impact. The study helped in clarifying the effect of oxygen on the interfacial phenomenon between magnesium. These results suggest that water could be identified seismologically if phase A is present in abundance in cold subducted slabs.This study describes results from mechanical tests conducted on magnesium single crystals in comparison with polycrystalline magnesium. Sessile drop technique was used for the purpose of analysis. The hydration of forsterite to phase A decreases the bulk and shear moduli by about 18 and 21%, respectively, while both compressional Vp and shear Vs wave velocities decrease by about 7%. Hardness measurements were conducted on singlecrystal magnesium oxide cleaved in laboratory air and in nitrogen. The axial compressibility of the hexagonal (P63) structure is highly anisotropic with the c-axis, which is perpendicular to the distorted close-packed layers, approximately 21% stiffer than the α-axis, in agreement with previous compression studies. The equipment used was a Tinius Olsen Izod. The impact toughness of the single crystal and polycrystalline Mg samples was explored at the Cincinnati Testing Labs. The present acoustic measurements resolve discrepancies between the bulk moduli obtained in earlier compression studies. The polycrystalline magnesium blocks were compressed at a rate of 0.2 mm/min, while the single-crystal magnesium blocks were compressed at a rate of 0.1 mm/min. The Voigt-Reuss-Hill average for the adiabatic bulk and shear moduli are Ks = 106(1) GPa and μ = 61(1) GPa respectively. These results suggest that water could be identified seismologically if phase A is present in abundance in cold subducted slabs.ĪB - The single-crystal elastic properties of phase A have been investigated by Brillouin spectroscopy at ambient conditions. The hydration of forsterite to phase A decreases the bulk and shear moduli by about 18 and 21%, respectively, while both compressional Vp and shear Vs wave velocities decrease by about 7%. The fraction of amorphous regions also increases with increasing temperature, which is an important cause of the temperature softening effect. MgO purity is more than 99.90, with bulk density more than 3.5 g/cm 3. The present acoustic measurements resolve discrepancies between the bulk moduli obtained in earlier compression studies. At a strain rate of 10 10 s 1, the amorphous regions achieve a very high fraction during deformation, contributing to softening and smoother deformation of the single crystal. Magnesium oxide single crystal is made of high-purity MgO, produced in the process of producing high-purity fused magnesia. N2 - The single-crystal elastic properties of phase A have been investigated by Brillouin spectroscopy at ambient conditions. T1 - Single-crystal elastic properties of dense hydrous magnesium silicate phase A
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