# INTRODUCTION TO STRUCTURE OF METALS AND ALLOYS

**Crystalline Materials:**

- A crystalline material is one in which the atoms are situated in a repeating (or) periodic array over large atomic distances.

**Non Crystalline Materials:**

- Materials that do not crystallize are called non-crystalline (or) Amorphous materials

**Space Lattice:**

**Lattice**is the regular geometrical arrangement of points in crystal space.

- The atoms arrange themselves in distinct pattern in space is called a
**Space Lattice**. - Atoms in crystalline materials are arranged in a regular 3 – Dimensional repeating pattern known as
**Lattice Structure**. - They are divided by network of lines in to equal volumes, the points of intersection are known as
**Lattice Points**.

**Unit Cell:**

- It is the smallest portion of the lattice which repeated in all directions.
- 3D visualization of 14 Space Lattices are known as
**Bravai’s Space Lattice**. - If a unit cell contains lattice points only at it’s corners, then it is called
**Primitive Unit Cell (or) Simple Unit Cell.** - Three edge length x,y, & z and three interaxial angles α, β, & γ are termed as
**Lattice Parameters**.

**Crystal System:**

- It is a scheme by which crystal structures are classified according to unit cell geometry.

**Types of Crystal Systems:**

- Cubic
- Tetragonal
- Hexagonal
- Orthorhombic
- Rhombohedral
- Monoclinic
- Triclinic

**Crystal Systems**

**Simple Crystal Structure:**

**Body Centered Cubic Structure (BCC)**

- Unit cell contains 2 atoms
- Lattice Constant a= 4r / √3, where r is atomic radius
- Atomic packing factor APF = 0.68
- Metals are Vanadium, Molybdenum, Titanium, Tungsten

**Face Centered Cubic (FCC)**

- Unit cell contains 4 atoms
- Lattice Constant a= 4r / √2, where r is atomic radius
- Atomic packing factor APF = 0.72
- FCC structures can be plastic deformed at severe rates
- Metals are Copper, Aluminum, Phosphorous, Nickel, Cobalt etc

**Hexagonal Closed Packed Structure (HCP)**

- Unit cell contains 3 atoms
- Axial ratio c/a, where ‘c’ is Distance between base planes, ‘a’ is Width of Hexagon
- Axial Ratio varies from 1.58 for Beryllium to 1.88 for Cadmium (Therefore a=2.9787, c=5.617)
- Atomic packing factor APF = 0.74
- Metals are Zinc, Cadmium, Beryllium, Magnesium etc

**Crystallographic Planes and Directions**

The Layers of atoms in the planes along which atoms are arranged is known as “Atomic” (or) “Crystallographic planes”.

**Miller Indices:**

Miller Indices is a system of notation that denotes the orientation of the faces of a crystal and the planes and directions of atoms within that crystal.

**Miller Indices for Planes:**

**1. The (110) surface**

Intercepts : *a* , *a* , ∞

Fractional intercepts : 1 , 1 , ∞

Miller Indices : **(110)**

**2. The (111) surface**

Intercepts : *a* , *a* , *a*

Fractional intercepts : 1 , 1 , 1

Miller Indices : **(111)**

The (100), (110) and (111) surfaces considered above are the so-called low index surfaces of a cubic crystal system.

**3. The (210) surface**

Fractional intercepts : ½ , 1 , ∞

Miller Indices : **(210)**

- Why Is Everyone Talking About Non-Conventional Energy Sources For the Future Energy Crises? | You Will Never Believe These 5 Bizarre Truths Behind Renewable Energy Sources For the Future Energy Crises92 / 100 Powered by Rank Math SEO Non-conventional energy sources for the future energy crises The subject of non-conventional energy sources will be discussed in this post. Energy is the top priority throughout the world. This is mainly because nations rely primarily on fossil fuel energy sources, whose resources are depleted because of overuse. The other common
- Prime Movers | How Are Prime Movers Classified? | 10 Explanation On Why Prime Movers Is So Important.93 / 100 Powered by Rank Math SEO Prime Movers and Different Forms of Energy Resources This article provides the fundamental details of the different types of prime movers used to produce mechanical energy in our daily lives. The different energy sources used by primary movers are also included. Introduction to Prime Mover Prime Mover
- Hydropower Plants vs Thermal Power Plants | 5 Things You Need To Know About Hydropower Plants Over Thermal Power Plants90 / 100 Powered by Rank Math SEO Hydro and thermal power Plants: Importance and Related problems Thermal power stations and hydropower plants project mainly address the current world’s energy needs. This article discusses the functioning of thermal power and hydropower plants. It also examines the problems of these two power plant types. The progress
- How Thermo-flask can keep heat for a longer period of time? Everything You’ve Ever Wanted to Know About Vacuum Flask In 10 Simple Steps93 / 100 Powered by Rank Math SEO Thermo-Flask The article demonstrates the scientific explanation behind this thermo-flask bottle. Three different modes of heat transfer such as conduction, conviction and radiation transfer. For users’ interest, the best use of thermo flasks is also incorporated. Today the thermo-flask bottle (Vacuum flask or thermos or Dewar flask, Dewar Bottle)
- Why The 1960s Vintage Personal Cars Had Been So Popular Till Now?Do you remember the classic 1960s vintage personal cars? We recall a couple of them, maybe only which we couldn’t help but watch them drive down the road as a Chevy Impala. Of all, the 1960s contributed to the right direction for manufacturers of cars. After all, there isn’t a better era than the 1960s if you are a fan of classic cars (or just cars in specific).

## 1 comments on “Introduction | Structure of Metals and Alloys | Crystalline materials”