Ch 1: Introduction to Materials Science and Engineering

what is materials science?

practice of investigating relationships between structures and properties of materials

what is materials engineering?

practice of creating products from existing materials and processing techniques

why are materials important?

because they lead to advancement in society

• ex: Stone Age, Bronze Age, Iron Age

why is it important for engineers to understand materials?

so the correct materials and processing techniques are used

what is processing?

the rate of cooling from a high temp (ºC/s)

processing affects ____

structure

structure affects____

hardness (BHN)

what are the 3 most common types of materials?

• metals

• polymers/plastics

• ceramics

characteristics of metals?

• strong

• ductile (pliable)

• high thermal conductivity

• high electrical conductivity

• opaque

• reflective

why do metals have high thermal and electrical conductivity?

because the valence electrons in metals are free to roam

what are polymers/plastics?

compounds of non-metallic elements

characteristics of polymers/plastics?

• soft

• ductile

• low strength

• low density

• low thermal conductivity

• low electrical conductivity

• opaque

• translucent or transparent

what are ceramics?

compounds of metallic and non-metallic elements

• ex: oxides, carbides, nitrides, sulfides

characteristics of ceramics?

• hard

• brittle

• low thermal conductivity

• low electrical conductivity

• opaque

• translucent or transparent

what are the steps of material selection?

1. determine properties for an application

2. identify candidate materials from a list of properties

3. specify processing technique for best candidate material

what are the 6 categories of material properties?

• mechanical

• electrical

• thermal

• magnetic

• optical

• deteriorative

what do mechanical properties affect?

hardness of a material via carbon content

_______ carbon content increases hardness of steel

increasing

what do electrical properties affect?

electrical resistivity (resistance in ohms) of a material

_____ temp increases resistivity

increasing

_____ impurity content increases resistivity

increasing

deformation _____ resistivity

increases

what do thermal properties affect?

thermal conductivity (ability to conduct heat) of a material

_____ impurity content increases thermal conductivity

decreasing

more porous materials are ___ conductors of heat

poor

what 2 things do magnetic properties affect?

• magnetic storage

• magnetic permeability vs composition

what does optical properties affect?

light transmittance of a material

more porous/grainy compounds have ____ transmittance

poor

what do deteriorative properties affect?

the structural integrity of a material

what can diminish stress-corrosion craking?

heat treatment