Introduction

Metals and alloys still constitute the most important group among engineering materials, and the demand for metallic materials with higher strength and special properties is on the increase with the advancement of technology. However, a serious drawback of metallic materials (and of other materials too!) is the deterioration in properties originating from their interaction with the environments in which they are to perform. Often this leads to a premature failure of metallic components with the allied hazards of plant shutdown and loss of economy, environmental pollution, and risk to human lives. The annual direct loss of natural resources, i.e., metals, due to environmental degradation is also substantial.