Engineering Materials

Abstract

The existence of the Stone, Bronze, and Iron Ages points to the importance of materials in humankind's development. The corresponding materials were used for art and jewelry, but most prominently for structural applications—as tools and weapons. While the ages themselves define step changes in material strength and durability, there was also significant material development within each age, such as the evolution from pure copper to alloys with tin, arsenic, and other metals in the Bronze Age. In a sense, we are still partially in the Iron Age, as steel (along with concrete) is the dominant structural material in our modern infrastructure, and continues to evolve in performance. For example, today's steels are significantly stronger and less prone to embrittlement than steel used for the RMS Titanic a century ago. On the other hand, we increasingly use specialty materials, such as polymer-metal composites, for high strength-to-weight ratio applications, and thermal-barrier coatings on Ni-based superalloys to operate turbines at very high temperatures. Most recently, the additive manufacturing revolution has opened up new possibilities for materials by design, where enhanced flexibility in composition, microstructure, and topological optimization relative to conventional processing methods offers many new opportunities and challenges.