In this paper, mechanical characteristics of the aluminum layer coated with graphene are investigated by performing numerical tensile experiments through classical molecular dynamics simulations. Based on the results of the simulations, it is shown that coating with graphene enhances the Young’s modulus of aluminum by 88% while changing the tensile behavior of aluminum with hardening–softening mechanisms and significantly increased toughness. Furthermore, the effect of loading rate is examined and a transformation to an amorphous phase is observed in the coated aluminum structure as the loading rate is increased. Even though the dominant component of the coated hybrid structure is the aluminum core in the elastic region, the graphene layer shows its effects majorly in the plastic region by a 60% increase in the ultimate tensile strength. High loading rates at room temperature cause the structure transforms to an amorphous phase, as expected. Thus, effects of loading rate and temperature on amorphization are investigated by performing the same simulations at different strain rates and temperatures (i.e., 0, 300, and 600 K).

In the present study, gradient microstructure and texture development in wedge-based severe plastic burnishing of oxygen-free high conductivity copper was investigated. Microstructural response and evolution of crystallographic texture in severe surface plastic deformation was shown to be controllable in terms of both magnitude and gradient through control of the incident wedge angle and burnishing parameters. Equiaxed ultra-fined grains and micro/nanoscale elongated grains were produced in the subsurface region, which is indicative of dynamic recrystallization at large strains in the subsurface. Subsurface regions exhibited a significant fraction of shear texture components along the 〈110〉 partial fibers. Texture evolution simulated using the visco-plastic self-consistent framework revealed variations in strain level controlling different mechanisms for rotation of these partial fibers from their ideal orientation. Controllability of subsurface properties and microstructure for such materials is briefly discussed. These results allude to fundamental limits in material processing by severe shear using scalable deformation configurations.

The mechanical behavior of a Zircaloy-4 sheet as induced by a pulsed laser was studied with an accurately developed computational process that was validated with experiments. A modified Gaussian model of the heat source and the use of experimentally obtained thermal and mechanical properties of Zircaloy-4 in the computational process provided reliable simulation results of the phase transition and mechanical deformation of Zircaloy-4. A parametric study of the pulsed laser welding conditions of Zircaloy-4 was undertaken using the developed computational process. The analyzed parameters were the laser power, pulse duration, and pulse frequency. The simulation results revealed that the deformation was significantly dependent on the geometry of the molten zone and the heat-affected zone, which can be designed by the analyzed laser parameters.

Mechanical properties are vital for living cells, and various models have been developed to study the mechanical behavior of cells. However, there is debate regarding whether a cell behaves more similarly to a “cortical shell – liquid core” structure (membrane-like) or a homogeneous solid (cytoskeleton-like) when experiencing stress by mechanical forces. Unlike most experimental methods, which concern the small-strain deformation of a cell, we focused on the mechanical behavior of a cell undergoing small to large strain by conducting microinjection experiments on zebrafish embryo cells. The power law with order of 1.5 between the injection force and the injection distance indicates that the cell behaves as a homogenous solid at small-strain deformation. The linear relation between the rupture force and the microinjector radius suggests that the embryo behaves as membrane-like when subjected to large-strain deformation. We also discuss the possible reasons causing the debate by analyzing the mechanical properties of F-actin filaments.

Carbon nanotube (CNT)-reinforced magnesium (Mg) matrix composites were synthesized using a powder metallurgical method and tested compressively along the plane normal and in-plane orientations. Yield strengths of composites were significantly increased by 35–129% compared with that of pure Mg. With the increase of CNT weight percentage, yield strength first increased until reaching a critical CNT weight percentage and then decreased. Twinning operated in the in-plane samples when CNT weight percentage was less than or equal to 0.5%, whereas twinning operation was not observed in all plane normal samples and the in-plane samples with 1% or higher CNT weight percentage. Severe plastic deformation was exhibited in fracture surface images with low magnification, whereas intrinsic brittle fracture feature was observed under high magnification. A theoretical model incorporating the Orowan strengthening and the thermal expansion mismatch strengthening was utilized and made good yield strength predictions.

The following article is based on the Von Hippel Award presentation given by Julia Weertman of Northwestern University on December 3, 2003, at the Materials Research Society Fall Meeting in Boston.Weertman received the award for “her lifelong exceptional contributions to understanding the basic deformation processes and failure mechanisms in a wide class of materials, from nanocrystalline metals to high-temperature structural alloys, and for her inspiring role as an educator in materials science.” It has been said that “the best things come in small packages,” and that is certainly in Weertman's mind in this presentation.She has spent much of her career “in pursuit of the small.” In this article, she first looks back at her experiences studying grain-boundary cavities and life in the spaces between grains.She then fast-forwards to modern work on nanocrystalline mechanical behavior, confirming that such nanocrystalline materials are indeed strong, but also brittle.Some of her experiences in studying these phenomena are also described.