The present book included three of the published papers, which have been chosen in CSA's Mechanical & Transportation Engineering Abstracts Database, America, 2005. Also, one of the published paper has the name of " New lead free solder alloy". Also one paper has been published in Key to metals,2012. In this book, we explained some basic concepts of metallic alloys, types and applications of metallic alloys. Furthermore we explained the types of solder alloys. In addition, illustration the importance of the rapid solidification technology that is used for producing alloys with improved properties.