Scratch testing, as a mature technique for coating adhesion quantification, has been widely adopted by both industrial and academic fields in recent years. Following the urgent needs of very small materials characterization, nano-scratch testing has gradually replaced the traditional pull-off test for the study of ultra-thin film properties. In this research, the relationship between the adhesion strength and film/substrate mechanical properties was investigated to provide fundamental but crucial knowledge of the scratch mechanism. Scratch tests were performed on different film/substrate combinations using a Nano Scratch Tester with a sphero-conical diamond indenter. A progressive load mode was employed to cause coating failure during scratch on the film surface. The critical values of different failure mechanisms, such as cracking and delamination were accurately determined according to the scratch panorama image, penetration and residual depth data. In addition, the hardness (H) and modulus (E) values of the thin films and substrates were measured with an Ultra Nanoindentation Tester. The scratch critical failure loads were then plotted versus film/substrate H and E ratios. A unique relationship was found between these parameters that could help understand the true mechanism behind scratch adhesion and leverage this methodology to a new theoretical level.

Copper micro-crystal fracture mechanisms were discussed with the machining precisions under the several cutting conditions, such as cutting speed, cutting depth and width of grove formation by the diamond single crystal cutting tool which the scoop face of (100) crystal face. For the cutting test, the copper single at the size of 10 mm in diameter and 5 mm in height as the test piece which cut by single crystal diamond cutting tool with silicon oil on the shaper type ultra-precision cutting machine. Before groves cutting, the specimen surface was cut as flat by cutting-off tool (corner diameter; 50 mm, cutting width; 3.0 mm, scooping angle; 0 degree, and escape angle; 7.0 degree) at the work speed as 4000 mm/min and cutting depth of 5 μm. For the V-shape grove cutting, the flat copper surface was cut with the diamond-point cutting tool (V angle = 90 degree, scooping angle = 0 degree, and escape angle = 7.0 degree) at the work speed as 4-4000 m m/min and cutting depth of 0.1-10 μm for finishing machining. The cut machined surface was observed by optical microscope comparing the grove shapes. The diamond-point tool was also observed by optical microscope. As results of the cutting test of copper single crystal, the machining precision was better for the crystallographic direction of than the direction of under the deeper cutting profiles. The mechanisms of this fracture results considered that the slip plane of (111). On the other hand, shallow grove under 1.0 μm was better tracks scratched for the crystallographic direction of than the direction of . This result was also considered that the slip plane related to the fracture behavior. For copper crystal cutting in nanometric scale, the crystallographic direction was quite important.

This study has investigated the crack growth retardation effect due to plural nano-scale voids in Cu single crystals using a molecular dynamics (MD) method. Focusing on an interaction between nano-scale voids and dislocations, we have evaluated the optimum placement for crack growth retardation. MD simulations showed that the dislocation activity was further enhanced due to plural nano-scale voids continuously placed on the primary slip direction. The significant ductility enhancement and slight yield stress increase due to the crack shielding effect of nano-scale voids were observed.

Mechanical behavior of ultra-fine grained (UFG) steel fabricated by high pressure torsion (HPT) was investigated by micro-sized compression test of a micro-sized pillar with uniform dimensions (non-tapered, non-filleted) carefully fabricated by FIB milling. After HPT process, grains were elongated to shear direction and its grain size was decreased down to 300 nm in diameter with increasing strain amount. Compression test confirmed that the uniform elongations of ultra-fine grained materials were lower than 3% and do not depend on the grain size.

The stability of elongated single- and multi-layered graphene nanoribbons (GNRs) are investigated by molecular-dynamics simulation. In order that GNRs are to be modeled as nanobridges connecting two terminals of electronic devices, the short edges of the GNRs are constrained. The distances between the two constrained edges are gradually increased, and the GNRs are uniaxially strained. The energies and out-of-plane deformations of such uniaxially strained GNRs are examined. The energies of multi-layered GNRs will be lower than those of isolated GNRs because the surface areas of multi-layered GNRs are smaller than the total area of the isolated GNRs. Understanding the relationship between the out-of-plane deformations and strain will lead to the control of the ripple structures of GNRs.

In this work, the behavior of molecules in thin-film lubricants, several tens of nanometers thick, is studied by in situ reflection infrared spectroscopy and by molecular dynamics simulations. The effect of fatty acid additives on the properties of these interfacial films is also studied. The results of these experiments are presented and interpreted, and the latest outcomes of molecular dynamics simulations are discussed. It is concluded that the molecular orientation in thin films of interfacial materials is markedly affected by the use of additives.

Electrochemical dissolution of ionic species into a solid is an area of great interest in several fields including nanoscale patterning and energy storage. Such dissolution is strongly influenced by several factors e.g., work function difference, dislocation density, grain size, and number of grain boundaries. These parameters are strongly influenced by mechanical deformation of the ionic conductor. Here we characterize such a system of silver (Ag) and silver sulfide (Ag2S), where incorporation of Ag into the solid ionic conductor, Ag2S, is dramatically influenced by mechanical deformation. We show more than three-fold dissolution rate enhancement when the polycrystalline conductor is compressed to one-third of its original size. We attribute this enhancement to increased dislocation density which is supported by the high current densities observed during dissolution. Additionally, reduced electronic currents suggest most of this contribution comes from increased reaction at the metal-conductor interface. Our studies have important applications in areas involving ionic transport including direct metal patterning and energy storage technology.

A reversible-phase transformation process to convert coarse-grained polycrystalline cubic-Y2O3 directly into the nanocrystalline state is being developed. The process involves a forward cubic-to-monoclinic phase transition under high pressure and a backward transformation from monoclinic-to-cubic under a lower pressure. The process has been used to reduce the grain size of fully dense cubic-Y2O3 from 300 μm to 0.1 μm. A surface modification effect, comprising a columnar-grained structure, has also been observed. Preliminary work indicates that the surface structure is modified, apparently formed by interaction between the graphite heater and sample.

A nondeterministic multiple scale approach based on numerical solution of the Monte-Carlo master equation coupled with a standard finite-element formulation of material mechanics is presented. The approach is illustrated in application to the long-term evolutionary processes of self-diffusion, precipitation and crack/void healing in nanocrystalline fcc and bcc solids. Effect of static and dynamic loading patterns on the crack healing rates are investigated. The approach is widely applicable to the modeling and characterization of advanced functional materials with evolutionary internal structure, as well as emerging behavior in materials systems.

Shape Memory Alloys (SMA) undergo reversible martensitic transformation in response to changes in temperature or applied stress, exhibiting specific properties of superelasticity and shape memory. At present there is a high scientific and technological interest to develop these properties at small scale, to apply SMA as sensors and actuators in MEMS technologies. In order to study the thermo-mechanical properties of SMA at micro and nano scale, instrumented nano indentation is being widely used for nano compression tests. By using this technique, superelasticity and shape memory at the nano-scale has been demonstrated in micro and nano pillars of Cu-Al-Ni SMA. However the martensitic transformation seems to exhibit a different behavior at small scale than in bulk materials and a size effect on superelasticity has been recently reported. In the present work we will overview the thermo-mechanical properties of Cu-Al-Ni SMA at the nano-scale, with special emphasis on size effects. Finally, the above commented size effects will be discussed on the light of the microscopic mechanisms controlling the martensitic transformation at nano scale.

Powder polymer processing techniques were evaluated as a means to generate homogeneous immiscible polymer blends without the high residence times at elevated temperature and high shear rates required by extrusion. Using emulsion polymerized and cryogenically jet pulverized PMMA and HDPE powder precursors, blends were prepared with morphologies comparable to extruded blends. Advanced EDS imaging methods combined with SiO2 marker spheres enhanced electron imaging and analysis of all blend phases. These processing methods will be useful in producing polymer blends from fragile polymers, such as those used in biomedical applications, that cannot tolerate the temperature or shear rates of conventional melt processing.

Nanoindentation results are very sensitive to tip rounding and neglecting the value of the tip radius produces erroneous estimation of the material elastic properties. In this study we investigate the effect of tip radius on the estimation of the Elastic modulus by means of finite element analysis of Berkovich and conical tips with different tip radii. Our numerical results were already supported by an experimental study on fused silica with Berkovich tips with different tip radii. The use of classical Oliver Pharr equation overestimated the Elastic modulus. A new analytical model that modifies the Oliver Pharr equation to consider the value of the tip radius is employed to derive the Elastic modulus from load displacement curves yielding improved results compared to the classical Oliver Pharr equation.