Introduction to Materials Science Materials Science An interdisciplinary

Introduction to Materials Science

Materials Science • An interdisciplinary study that combines sciences such as metallurgy, physics, chemistry and engineering to solve real-world problems with real-world materials in an acceptable societal and economical manner.

What is material science? Definition 1: A branch of science that focuses on materials; interdisciplinary field composed of physics and chemistry. Definition 2: Relationship of material properties to its composition and structure.

Example • A main reason why iron has been a significant material for a long time is not that it is ‘strong’, it is because we can change its properties by heating and cooling it. • The ability to change the properties and/or behaviour of a material is what makes most materials useful and this is at the heart of materials science.

Materials have ‘driven’ our society • Stone Age – naturally occurring materials – special rocks, skins, wood • Bronze Age – casting and forging • Iron Age – high temperature furnaces • Steel Age – high strength alloys • Non-ferrous and polymer Age – aluminium, titanium and nickel (superalloys) use in aerospace; silicon in information technology; plastics and composites for food preservation, housing, aerospace, … • Exotic Materials Age? Nano-material and biomaterials. .

Classes of materials • • • Ionic crystals Covalent materials Metal and alloys Semiconductors and Superconductors Polymers Composite materials Ceramics Catalysts Biomaterials Exotic and strange materials. . .

We are going to mainly look at four classes of materials 2. Ceramics 1. Metals - clay - aluminum - silica glass - copper - alumina - steel (iron alloy) - quartz - nickel - titanium 3. Polymers - polyvinyl chloride (PVC) - Teflon - various plastics - glue (adhesives) - Kevlar 4. Composites - wood - carbon fiber resins - concrete semiconductors (computer chips, etc. ) = ceramics, composites nanomaterials = ceramics, metals, polymers, composites

Types of Materials - Activity B C D A tile popsicle stick plastic bag paper clip A metal B Ceramic C composite D polymer

Plastic/Elastic Deformation • When a sufficient load is applied to a material, it will cause it to change shape = deformation. • Elastic deformation – a temporary shape change that is self-reversing after the force is removed, so that the object returns to its original shape. • Plastic deformation – permanently deformed material, e. g. metals can be bent into a different shape prior to fracture whereas a tile has no plastic behaviour as it doesn’t form a different shape before fracturing.

• What are the differences between metals and ceramics when subjected to force? • Under extreme force, metals plastically deform, whereas ceramics elastically deform. Metals are, typically, not subject to brittle fracture, while ceramics are very brittle.

• What similarities do polymers and metals have when subjected to a force? • They both can behave elastically under mild forces, but do predominately plastically deform. Metals and polymers can deform or change shape to extreme dimensions, hence have high ductility.

• Why would a metal be preferred as a bridge building material as opposed to a ceramic material? • Metals are less susceptible to brittle fracture and can deform (give a warning) prior to failure. Brittle fracture is a catastrophic fracture with no warning signs.