High-Temperature Grain-Boundary Embrittlement and Creep

The subject of material failure is vast and expanding rapidly as newer tools for micromechanical examinations and newer materials are being developed and their uses are increasing in wide‐ranging applications, such as nanoengineering. High‐temperature embrittlement has equivocally been linked to the formation of “intergranular voids and cracks”. Griffith's theory of crack propagation is unmistakably the most powerful concept that provided a fertile ground for the study of fracture in brittle solids. The practical use of acoustic emission or microseismic techniques is growing and has become an integral branch of the wide‐ranging field of nondestructive testing. The Hall‐Petch effect is rooted in the minds of most engineers and materials scientists familiar with fracture behavior of metals, alloys, and nonmetallic materials at room temperature. The chapter explores the role of grain‐boundary shearing in cracking further and examines the link between microcracking at elevated temperature and delayed elasticity.