Material Science pdf Flashcards
Substances that human assembled or produced as products, appliances, inventions, various constructions
Materials
Materials used in the field work of engineering
Materials Engineering
Basic knowledge about the relationships between internal structure and properties including processing of materials
Materials Science
its role is to develop or synthesize new materials
Materials Scientist
is called upon to create new products or systems using existing materials, and/or to develop techniques for processing materials
Materials Engineer
Structure (4 Levels)
Stucture of atomic
Structure of Crystal
Microscopic
Macroscopic
Properties (7 types)
Chemical Properties
Physical Properties
Mechanical Properties
Thermal Properties
Electrical Properties
Magnetic Properties
Optical Properties
Process of processing material by either heat or mechanical force
Processing
3 basic materials
Metals
Ceramics
Polymers
Materials in this group are composed of one or more metallic elements (such as iron, aluminum, copper, titanium, gold, and nickel)
Metals
Used in reference to a metallic substance that is composed of two or more elements
Metal Alloys
Compounds between metallic and nonmetallic elements; they are most frequently oxides, nitrides, carbides
Ceramics
those composed of clay minerals (i.e., porcelain), as well as cement and glass
Traditional Ceramics
Include the familiar plastic and rubber materials and many of them are organic compounds that are chemically based on carbon, hydrogen, and other nonmetallic elements (O, N, and Si)
Polymers
Examples of Polymers
Polyethylene (PE)
Nylon
Poly vinyl chloride (PVC)
Polycarbonate (PC)
Polystyrene (PS)
Silicone Rubber
Composed of two or more individual materials, which come from the categories (Metals, Ceramics, Polymers)
Composites
2 Types of Composites
Natural (Wood, bone etc.)
Man-made (Synthetics)
These materials are typically traditional materials whose properties have been enhanced, and also newly developed, high performance materials. They may be of all material types
Advanced Materials
Examples of Advanced Materials
SemiConductors
Biomaterials
Smart Materials
Nanoengineered materials
A group of new and state-of-the-art materials able to sense changes in their environment and then respond to these changes in predetermined manner
Smart Materials
Employed in components implanted into the human body for replacement of diseased or damage body parts
Biomaterials
Have electrical properties that are intermediate between the electrical conductors and insulators
Semiconductors
These are called “Materials by design”. This ability to carefully arrange atoms provide opportunities to develop mechanical, electrical, magnetic and other properties that are not otherwise possible
Nanoengineered materials
The physical properties of materials is predicted on a knowledge of the interatomic forces that bind the atoms together
Interatomic Bonding
It necessarily involves the valance electrons
Primary Bond
The interaction between two isolated atoms as they are brought into close proximity from an infinite separation
Atomic Bonding
3 Primary bond
Ionic
Covalent
metallic
the atoms acquire stable or inert gas configurations and is always found in compounds that are composed of both metallic and nonmetallic elements
Ionic
Valence electrons are not bound to any particular atom in the solid and are more or less free to drift throughout the entire metal
Metallic bonding
Two atoms that are covalently bonded will each contribute atleast one electron to the bond, and the shared electrons may be considered to belong to both atoms
Covalent bonding
seperation of positive and negative portions of an atom or molecule
Electric Dipole
result from attractive forces between electric dipoles, of which there are two types - induced and permanent
Secondary Bond
the spatial arrangement of atoms represented as solid spheres
Crystal Structure
Two features are: coordination number (or number of nearest neighbor atoms) and atomic packing factor (the fraction of solid sphere volume in the unit cell)
Metallic Crystal Structure
3 types of metallic crystal structure
Face-cented cubic (FCC)
Body-cented cubic (BCC)
Hexagonal close packed (HCP)
The crystal structures of these materials for which the atomic bonding is predominantly ionic and determined by the charge magnitude and the radius of each kind of ion and crystalline and non crystalline states are possible examples is Salt
Ceramic Crystal Structure
composed of many small crystals or grains having different crystallographic orientations
Polycrystalline materials
specified in terms of indexing schemes. The basis for the determination of each index is a coordinate axis system defined by the unit cell for the particular structure
Crystallographic Planes
a classification scheme for crystal structures on the basis of unit cell geometry
Crystal System
when a specific material can have more than one crystal structure
Polymorphism
the directionality dependence of crystal properties
Anisotropy
solid materials for which there is an absence of long range atomic regularity or order
Non-Crystalline Solids
the characteristics of a material that relate to its behavior in chemical reaction
Chemical Properties
the characteristics that are used to describe a substance in the absence of external forces
Physical Properties
the characteristics that describe the behavior under the application of force
Mechanical Properties
the property of regaining the original shape upon the removal of the external load
Elasticity
4 types of Elasticity
Young’s Modulus - Direct Proportionality
Shear Modulus - Lateral Contraction
Bulk Modulus - Equal stress in all direction
Modulus of Rupture - Bending or torsion
the property of material by virtue of which permanent deformation can occur
Plasticity
the capacity of a material to absorb energy within the elastic range
Resiliency
the stress at which the material exhibits a specified limiting permanent set
Yield Strength
the maximum stress to which a material may be subjected before failure occurs
Ultimate Strength
the quality of material by virtue of which it may be plastically elongated
Ductility
A measure of the total energy-absorbing capacity of the material
Toughness
quality of material by virtue of which it may be plastically compressed
Malleability
Resistance of material from scratching, filing, wear, penetration, machining
Hardness
exhibit a higher proportional limit or hardness after successively greater plastic deformation
Strain Hardening
aging for a long time in a room temperature to return to yield point
Strain Aging
failure which takes place as a result of repeated or altering stresses
Fatigue
the characteristic of continued plastic deformation under a constant stress
Creep
factors affecting the endurance limit
Stress Concentration
Corrosion
a stress that will produce failure in some specified number of cycles of the stress applications
Endurance Strength
Effects of temperature
Loss of Metal
Formation of the surface Crack
change in properties
Factor of Safety
- Variations of the properties of material
- The uncertainties of computation of stress, magnitude, and stress distribution
- Quality of the manufacturing operations
- Dangers of Personal Injury
- The necessity of maintaining economy of material and of minimizing weight
- The influence of Uncertainties
- Extent of Inspection
Selection of Materials
- The materials must satisfy the strength requirements
- The materials must be capable of being fabricated into the desired form
- The cost of material must be low
- The material must be available for use at the required time
Metals or alloys having high percentage of iron
These Materials are used where high strength is required at relatively low cost
Ferrous Materials
3 types of ferrous materials
- Steel - Alloy of iron and carbon (1.5 %)
- Cast Iron - Alloy of iron and carbon (4.5%)
- Wrought Iron - Almost pure Iron (99.9%)
Classification of Steels
- Low Carbon Steel
- Medium Carbon Steel
- High Carbon Steel
Classification of Iron
- Grey Cast Iron
- White Cast Iron
- Malleable Cast Iron
- High Duty Cast Iron
- Alloy Cast Iron
Metals Other than Iron
In Pure Form, they are used with other materials in order to obtain a certain property like corrosion resistance, ductility, hardness, etc.
Non-Ferrous Materials
Deformation of temperature high enough for recrytallization
Large Deformations
Metal Fabrication (Hot Working)
Deformations below recrystallization
Strain Hardening occurs
Small deformations
Metal Fabrication (Cold Working)
Types of Forming (Metal Fabrication)
- Forging
- Hammer Forging
- Press Forging
- Drawing
- Rolling
- Extrusion
Deformation process in which work thickness is reduced by compressive forces exerted by two opposing rolls
Rolling
A cold working process in which the work piece is pulled through a tapered hole in a die so as to reduce its diamater
Drawing
Forming a preheated workpiece by using a force created by hydraulically driven ram causing the metal to be squeezed into the die cavity by the static pressure
Press Forging
a process used to create an objects of a fixed cross-sectional profile. A material is pushed through a die of the desired cross-section
Extrusion
the process of producing metal/alloy component parts of desired shapes by pouring the molten metal/alloy into a prepared mould and then allowing the metal/alloy to cool and solidify
Casting
a process of using sand as the primary material to mold various metallic products
Sand Casting
includes wax pressure, wax repair, group tree, dip slurry, wax melting, casting metal liquid and post processing process
Investment Casting
3 stages of investment casting
Stage 1 - Mold formed by pouring plaster of paris around wax pattern
Stage 2 - Wax is melted and then poured from mold-hollow mold cavity remains
Stage 3 - Molten Metal is poured into mold and allowed to solidify
A metal casting process that is characterized by forcing molten metal under high pressure into a mold cavity
Die Casting