Microstructural damage mechanisms

Therefore, characterizing the macromechanical properties of particulate polymer composites without studying the microstructural damage mechanisms and their effects on macromechanical properties is not possible. 

There is a correlation between the mechanical and chemical data of figures 7-10. It is clear from the multilayer or lamellar structure of these in vitro lesions that they are formed by a complex demineralization process that cannot be explained by simple, diffusion-based models. The surface layer, which is extremely weak, has lost almost all of its Ca and P, except for a very small amount close to the surface. This region close to the surface is stronger than the body of the lesion, but still very weak when compared to the underlying enamel. The body of the lesion is extremely compliant and mechanically very weak. The weak interior and surface layers of the lesion make it particularly prone to damage when the surface is mechanically loaded. Collectively, the mechanical, chemical and structural data indicate that even the less demineralized surface zone (A on fig. 7, 8) does not have the same microstructure or mechanical strength as sound enamel. 

O. Siron, G. Chollon, H. Tsuda, H. Yamauchi, K. Maeda, andK. Kosaka, "Microstructural and mechanical properties of filler-added coal-tar pitch-based C/C composites the damage and fracture process in correlation with AE waveform parameters," Carbon, 38[9] 1369-1389.2000. 

S. Dunford, A. F rimavera, and M. Meilu-nas, Microstructural Evolution and Damage Mechanisms in Pb-Free Solder Joints During Extended — 40 °C to 125 C Thermal Cycles, IPC Conf. Proc., 2002, p S08-4-1-S08-4-13... 

Interestingly, even if the microstructural evolutions are different, advanced austenitic stainless steels and the Incolloy 800 alloy, which is close to nickel-based alloys, are subjected to the same creep damage mechanisms as martensitic steels and conventional austenitic stainless steels. The same modelings may be applied and lead to creep lifetime predictions in agreement with experimental data up to the longest experimental lifetimes published in the literamre. 

Steven O. Dunford, Anthony Primavera, Ph.D., and Michael Meilunas, "Microstructural Evolution and Damage Mechanisms in Pb-Free Solder joints During Extended -40°C to 125°C Thermal Cycles," IPC 2002, New Orleans, La. 

There are a number of reasons for the enhanced cycle life in nanoscale materials. First, the relatively open structure of nanoscale materials seems capable of accommodating a large volume expansion during lithiation. Secondly, the conventional mechanisms for microstructural damage are often absent in nanoscale materials. Dislocations are usually unstable in crystals with nanoscale dimensions (<20 nm) due to image forces, which attract the dislocation to the surface. For brittle materials such as silicon and... 

Dunford, S.O. Primavera, A. Meilunas, M. Microstructural evolution and damage mechanisms in Pb-free solder joints during extended -40 to 125°C thermal cycles. Proceedings, IPC Annual Meeting, New Orleans, LA, November 2002 S08-4-1 to 13. 

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