material science ch 1-5, Chapter 1: Introduction to Materials Science and Engineering

single crystal

-has high degree of perfection -> makes it transparent -a bunch of small single crystals together make it translucent

Single crystal

A crystalline material that is made of only one crystal (there are no grain boundaries).

Materials science

A field of science that emphasizes studies of relationships between the microstructure, synthesis and processing, and properties of materials.

Ceramics

A group of crystalline inorganic materials characterized by good strength, especially in compression, and high melting temperatures. Many ceramics have very good electrical and thermal insulation behavior.

Composites

A group of materials formed from mixtures of metals, ceramics, or polymers in such a manner that unusual combinations of properties are obtained (e.g., fiberglass).

Semiconductors

A group of materials having electrical conductivity between metals and typical ceramics/ polymers (e.g., Si, GaAs).

Polymers

A group of materials normally obtained by joining organic molecules into giant molecular chains or networks. Polymers are characterized by low strengths, low melting temperatures, and poor electrical conductivity. (plastic and rubber)

Polycrystalline material

A material composed of many crystals (as opposed to a single-crystal material that has only one crystal).

Crystalline material

A material composed of one or many crystals. In each crystal, atoms or ions show a long-range periodic arrangement.

Smart material

A material that can sense and respond to an external stimulus such as change in temperature, application of a stress, or change in humidity or chemical environment.

Alloy

A metallic material that is obtained by chemical combinations of different elements (e.g., steel is made from iron and carbon). Typically, alloys have better mechanical properties than pure metals.

Glass-ceramics

A special class of materials obtained by forming a glass and then heat treating it to form small crystals.

Thermoplastics

A special group of polymers in which molecular chains are entangled but not interconnected. They can be easily melted and formed into useful shapes. Normally, these polymers have a chainlike structure (e.g., polyethylene).

Thermosets

A special group of polymers that decompose rather than melt upon heating. They are normally quite brittle due to a relatively rigid, three-dimensional network structure (e.g., polyurethane).

Materials science and engineering tetrahedron

A tetrahedron diagram showing how the performance-to-cost ratio of materials depends upon the composition, microstructure, synthesis, and processing.

Glass

An amorphous material derived from the molten state, typically, but not always, based on silica.

Metal

An element that has metallic bonding and generally good ductility, strength, and electrical conductivity. -relatively dense compared to ceramics and polymers

Materials engineering

An engineering oriented field that focuses on how to transform materials into a useful device or structure.

Materials science and engineering (MSE)

An interdisciplinary field concerned with inventing new materials and improving previously known materials by developing a deeper understanding of the microstructure-composition-synthesis-processing relationships between different materials.

Physical properties

Characteristics such as color, elasticity, electrical or thermal conductivity, magnetism, and optical behavior that generally are not significantly influenced by forces acting on a material.

Grains

Crystals in a polycrystalline material.

Structure

Description of the arrangements of atoms or ions in a material. The structure of materials has a profound influence on many properties of materials, even if the overall composition does not change.

Processing

Different ways for shaping materials into useful components or changing their properties.

Fatigue failure

Failure of a material due to repeated loading and unloading.

Density

Mass per unit volume of a material, usually expressed in units of g/cm3 or lb/in.3

Plastics

Polymers containing other additives.

Mechanical properties

Properties of a material, such as strength, that describe how well a material withstands applied forces, including tensile or compressive forces, impact forces, cyclical or fatigue forces, or forces at high temperatures.

Grain boundaries

Regions between grains of a polycrystalline material.

Composition

The chemical make-up of a material.

Synthesis

The process by which materials are made from naturally occurring or other chemicals.

Polymerization

The process by which organic molecules are joined into giant molecules, or polymers.

Strength-to-weight ratio

The strength of a material divided by its density; materials with a high strength-to-weight ratio are strong but lightweight.

Microstructure

The structure of a material at the microscopic length scale.

nanomaterial

are less than 100 x10^-9m (apx 500 atoms) -allows for ottom up approach (building small blocks at a time) -size changes properties

structure

arrangement of internal components subattomic: involves electrons within the individual atom and interatons with their nuceli atomic: organization of atoms or larger groups of atoms (microscopic) (macroscopic is visible)

biomaterials

implanted into human body to replace diseased or damaged parts. must be compatible with body tissue

properties

mechanical, electrical, thermal, magnetic, optical and deteriorative

what is material science?

the investigation of the relationships between structures and properties of materials. Important to know how processing structure properties and performance all play a part in a material.