Strength Of Polycrystalline Materials Research Articles

Improved high temperature strength of copper-graphene composite material

The strength of polycrystalline materials at high temperatures is limited due to their poor resistance to grain boundary motion. A strategy to anchor the grain boundary of copper in 2-dimensional curvature by graphene was proposed and the copper-graphene composite was therefore fabricated. It was found that the hardness of Cu-0.5wt% graphene (GN) composite is almost same with that of Cu-0.5wt% graphite (GP) composite between room temperature and 450°C. However, the hardness of Cu-GN composite improves significantly above 450°C and is nearly twice of that of Cu-GP composite at 600°C, indicating the hindrance effect of graphene on the atom diffusion across grain boundary at high temperatures. On the other hand, the thermal expansion coefficient is lower for Cu-GN composite compared with that of Cu-GP composite, and the electrical conductivity of the Cu-0.5wt% GN composite remains 95.9 IACS%.

Elasticity, strength, and refractive index of argon at high pressures

High-pressure Brillouin spectroscopy of polycrystalline argon, measured using two scattering angles ($180\ifmmode^\circ\else\textdegree\fi{}$ and $70\ifmmode^\circ\else\textdegree\fi{}$), determines the isotropic elastic moduli, shear strength, equation of state, and refractive index of face-centered-cubic argon from 1.3 to 30 GPa at room temperature. The index of refraction $n=1.33--1.67$ over this pressure range. An Eulerian finite-strain analysis (Birch-Murnaghan equation of state) yields an isothermal bulk modulus and pressure derivative ${K}_{T}=15.1(\ifmmode\pm\else\textpm\fi{}1.1)\text{ }\text{GPa}$ and ${K}_{T}^{\ensuremath{'}}=5.4(\ifmmode\pm\else\textpm\fi{}0.3)$ at 2 GPa. The resulting equation of state agrees well with previous x-ray diffraction measurements, illustrating the suitability of high-pressure Brillouin scattering for characterizing the elasticity and strength of polycrystalline materials.

Effect of structural stresses on the strength of polycrystalline materials

Effect of structural stresses on the strength of polycrystalline materials