Anantha Padmanaban D

By Dattaguru Ananthapadmanaban

All modern day materials have to be characterized in order to understand their properties. Simple techniques can be used for macrostructural and microstructural characterization. Many a time, however, advanced techniques may be required in order to understand structure property relationships in a better way. Advanced characterization techniques include scanning electron microscope (SEM), transmission electron microscope TEM, nuclear magnetic resonance (NMR), synchrotron, X-ray fluorescence microscopy and a few others. Geopolymers have advanced to the level of nanogeopolymers, and in order to understand the fundamental properties of nanogeopolymers, it becomes imperative to gain a fundamental understanding of characterization methods. SEM, TEM, NMR and synchrotrons have been briefly described, and advances in these characterization techniques have been emphasized. Microstructures of common geopolymers have been discussed with special emphasis on nanogeopolymers.

Part of the book: Geopolymers and Other Geosynthetics

By Dattaguru Ananthapadmanaban and Arun Vasantha Geethan

Intermetallics are intermediate compounds formed between two metals. They are usually brittle. The presence of intermetallics leads to deterioration in mechanical properties. This chapter reviews the intermetallic compounds formed during the manufacture of lead-free alloys. Intermetallic compounds formed in ordinary lead-based alloys are also discussed. The role of rare earth, especially indium and lanthanum, additions on intermetallic formation is examined. Microstructures of intermetallics are analysed. Hardness values of lead-free alloys are compared with emphasis on type and nature of intermetallics. SEM photographs of lead-free solders are discussed with regard to type of fracture, and the role of intermetallics in nature of fracture is examined. Lastly, the general mechanisms of formation of intermetallics are touched upon, and these mechanisms are extended to intermetallic formation in lead-free alloys.

Part of the book: Lead Free Solders

By Dattaguru Ananthapadmanaban and K. Arun Vasantha Geethan

The nature of the fractured surface gives information about the type of failure. This chapter focuses on the study of the fractured surfaces. Solid-state welding processes, such as friction welding, friction stir welding, and laser welding, have been used for welding dissimilar joints in recent times. Different combinations of materials and different welding conditions give rise to changes in the morphology of the fractured surfaces. Material combinations that have been chosen in this study are industrially useful combinations such as titanium-stainless steel and aluminum-copper. An attempt has been made to study the fractured interfaces, mainly using scanning electron microscope (SEM). In order to achieve this objective, case studies have been made use of.

Part of the book: Engineering Failure Analysis