Chapter 1

1. Chapter 1:
The Structure of Materials and Binary Alloy System
1.0 The Structure of Materials and Periodic Table of the
Elements
1.1 The Structure Of Materials
1. Crystal structures or crystals :
Atomic arrangements which have a repetitive pattern in all the three
dimensions of space.
2. Molecules :
Two or more atoms combined chemically.
3. Microstructure :
The appearance of the structure of a material under a microscope
and consists of phase structure and grain structure.
4. All solid materials consist of a large number of particles called
molecules that are bonded together to form a bulk material.
Each molecule is further composed of tiny particles called atoms.
Individual properties of atoms and their arrangement in the
molecule determine the properties of the materials.
1.1.1 Atoms
 Atom is the basic unit of an element formed for all materials weither
for solid, gas or liquid.
 An atom consists of the nucleus and the electrons.
Atom Charge
Proton Positive
Neutron Neutral
Electron Positive
 The valence electrons are the outer electrons and are least firmly
bound to the atomic nucleus and revolve in the outer orbits
Fig 1 : The position of electron, nucleus and orbit in an atom
1.1.2 Elements (unsur)
 Elements is a combination of two or more same atoms bonding
together.
 Elements are pure substances.
 Example: Oxygen (O), hydrogen (H), aurum (Au), Carbon (C),
Helium (H)
1.1.3 Mixtures (campuran)
 Mixtures: Various kinds of atoms combined together but not
chemically.
1.1.4 Compounds (sebatian)
 Compounds: Various kinds of atoms combined in a definite
proportion, which is expressed by a chemistry formula.
 Example: hydroxide (H2O), hydrochloride (HCI),
carbon dioxide (CO2).
nucleus
electron
orbit/shell
valence electrons
Nuclues

2. 1.2 Atomic Numbers, Atomic Masses and Atomic Orbits
1. Atomic Numbers
 Neutral atom = numbers of proton = numbers of electron
2. Atomic Masses and Atomic Weight
 Atomic Weight = Atomic masses of an element
Atomic masses of Hydrogen
 Atomic Masses = atomic numbers
= number of proton + number of neutron
3. Atomic Orbits
 Using the 2n2 formula to state the total of atoms in every orbit,
where n is total of orbit
1st orbit, n = 1
Total of atom = 2 (1)2 = 2
2nd orbit, n = 2
Total of atom = 2 (2)2 = 8
1.3 Periodic Table of the Elements
1. It is a chart of list of elements which all the elements with same
chemical properties in one line as one group.
2. The horizontal rows of elements on the periodic table called periods.
The vertical columns called groups or families.
3. Characteristics :
i. 18 lines of boxes in vertical, 7 lines of boxes in horizontal
ii. 8 groups start with group I until VIII
iii. arrange by atomic number start with Hydrogen
iv. elements in same line horizontally has same total of orbits
v. chemical properties of an atom depend on total of valency atom
vi. when electron are followed from group I to group III, metal
properties of an element become lessen but total of electron will
increase and become the non-metal properties
vii. elements in group I has 1 electron in outer orbit, elements in group
II has 2 electron in outer orbit
viii. each period has same total of orbits
4. Usages :
i. to classified certain elements easier
ii. as a revision where elements reactive properties can be known (way
to the right, the reactive properties are lessen)
iii. elements in first group has same chemical properties
iv. easier to acknowledge certain unknown element and also its
properties and the usage
v. easier to analyze and understand every reaction between the
elements

3. 1.0 Crystal Structures
1. It is atomic arrangements which have a repetitive pattern in all the
three dimensions of space are called crystal structures or crystals.
2. There are 4 types well-known crystal structures and it was :
(i) simple cube
(ii) body centered cubic/ BCC
(iii) face centered cubic/ FCC
(iv) hexagonal close packed/ HCP
Simple Cube
Body Centered Cubic (BCC)
N
7
Nitrogen
14
2:5
Atom’s mass
Symbol
Element’s name
Electron
configuration
Atom’s
no
Simple Cube
8 atoms in corners x 1/8 =1 atom
e.g. natrium chloride (salt) Face Centered Cubic (FCC)
8 atoms in corners x 1/8 = 1 atom
6 atoms in faces x ½ = 3 atoms
Total = 4 atoms
e.g. silicon, nickel, cuprum,
aurum, platinum
single crystal grains
grain boundaries
Fig 2 : Structure and grain boundaries
Body Centered Cubic (BCC)
8 atoms in corners x 1/8 = 1 atom
1 atom in center = 1 atom
Total = 2 atoms
e.g. chromium, tungsten,
molybdenum, vanadium, sodium
(natrium)
Face Centered Cubic (FCC)
Hexagonal Closed Packed (HCP)
Hexagonal Closed Packed (HCP)
12 atoms in corners x 1/6 = 2 atoms
2 atoms in faces x 1/2 = 1 atom
6 atoms in sides x 1/2 = 3 atoms
Total = 6 atoms
e.g. magnesium, barium, zinc,
cadmium, cobalt

4. 1.5 Types of Bonding
1.5.1 Covalent Bonding
 Occurs when two atoms (same elements) have a tendency to accept
electrons which are satisfied for both by sharing the electron valency.
1.5.2 Metallic Bonding
 Occurs when two metal atoms have a tendency to give up their
electrons and shared with all atoms close to them and formed of an
electron cloud that spreads throughout the solid metal.
1.5.3 Ionic / Electrovalence Bonding
 Exists between two unlike atoms that had a strong tendency to give
up electrons (a metal), close to an atom that has a strong tendency to
accept electrons (a nonmetal) and allows a transfer of one or more
electrons depending on the valence of the atoms
 an example is natrium chloride (NaCl)
Before
Na Cl
2.8.1 2.8.7
After
Cl2 molecules. Couple of sharing electrons.
Cl Cl
OR
electron transferred
from natrium to
chlorine

5. 1.6 The Stages Of Grain Structures Formation
1. Solidification process occurs along with the grain formation.
2. Nucleus tips freely find their own way to much colder place.
3. Causing the nucleus to grow and expanding.
4. The expand will form the secondary dendrite arm with 90 to each
other.
5. This will continue until a structure called dendrite structure existed.
1.7 The Differences Between Base Metal and Alloy
1. Base metal
 metal has same elements, extreme properties and cannot fulfill the
need for engineering work.
 its characteristics :
(i) malleable – can be shape to many form
(ii) ductile – can be form to fine wire
2. Alloy
 a metal alloy is a combination of two or more metals or a metal
and a non-metals.
1.8 Types Of Solid Solutions
Disordered Solid Solution
 Solute and solvent atoms are randomly distributed on lattice sites
Ordered Solid Solution
 The atoms (solute and solvent) take up preferred positions and the
solution becomes ordered
Interstitial Solid Solution
 Atoms of small atomic radius fit into the empty spaces or interstices
of the lattice structure of the solvent atoms
Intermetallic Compounds
 made up of 2 or more elements producing a new phase with its own
composition, crystal structure and properties
nucleus
formation
dendrite
formation
solidification
end by the
existent of the
grain
dendrite formation
growth & the arm met
to form grain
boundaries
Solute atoms
Solvent atoms
Solute atoms
Solvent atoms
Solvent atoms
Solute atoms

6. 1.9 Terminologies In Phase Diagram
1. Phase
 Is a region that differs in structure or composition from another
region
2. Equilibrium Phase Diagram
 Are graphical representations of what phases are present in a
materials system at various temperatures, pressures and
compositions
3. Composition
 Are percentage of certain materials contains purposely or not
added to another material. With this it can cause changes in
phases, the properties and the shape of the microstructures.
4. Liquidus
 The temperature at which liquid starts to solidify under
equilibrium conditions.
5. Solidus
 The temperature which all liquid has completely solidified.
1.10 Binary Alloy System
1. Binary phase diagram is a phase diagram in which there are only two
components and a mixture of two metals (a binary alloy).