Lecture 1

Introduction to Metallurgy

What is Metallurgy? Metallurgy is a domain of materials

science and engineering that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their mixtures, which are called alloys.

Classification of Materials

RubberIn 1839 Charles Goodyear discovered vulcanization.

Evolution of planes over years

Ever since the Wright brothers built their Flyer back in 1903 , the materials used in airplane design have been constantly evolving.

First aircraftThe aircraft was built by Wright brothers in1903.The original Wright Flyer was comprised primarily of spruce and ash wood with muslin covering the wings. Its engine was made of Aluminium. It was having spurce and steel wire structure with fabric skin

Engine blocksIn 1903 Aluminium engine block were

discovered ,before most internal combustion

engine were made of cast iron .

First All-Metal Planes At a time when airplanes were made out of

fabric and wood, the German Junkers company manufactured an all-metal prototype that showed the aviation world that lighter metals could be used for aircraft. 

1916-Stressed Skin Construction  Stressed skin is a type of rigid construction,

intermediate between monocoque and a rigid frame with a non-loaded covering. A stressed skin structure has its compression-taking elements localized and its tension-taking elements distributed. 

1930-Increased Aluminium use Alclad and Duralumin were vastly used in

manufacturing planes. -Alclad is a corrosion resistant  aluminium sheet formed from high-purity aluminium surface layers metallurgically bonded to high-strength aluminium alloy core material.

- Aluminium, the main materials constituting duralumin are copper, manganese and magnesium. 

Stainless Steel constructor was also used for manufacturing planes .

Metals A metal is a crystalline material in which the ions

are connected indirectly through a field of free electrons

High stiffness Ductile High fracture toughness High density Good electrical and thermal conductivity Reactive and corrode rapidly Reflect light Example :- Gold, Silver, Copper

Ceramic A ceramic is an inorganic, nonmetallic solid material

comprising metal, nonmetal or metalloid atoms primarily held in ionic and covalent bonds.

Stiff, Hard Abrasion resistant, Corrosion resistant Heat resistant, thermal resistant Tensile strength (Brittle fracture strength)<

Compression strength (Crushing stregth) by almost 15 times

Difficult to design Example :- Alumina, Silicone Carbides, Silicon nitrides

Polymer Polymers are organic solids based on long

chains of carbon (or silicon) atoms Low density and strength Properties depend on temperature Low conductivity Modulus of elasticity is 50 times less than

that of metals Example :- Polyester, PVC

ElastomersA polymer with viscoelasticity and weak

intermolecular forces, generally having low youngs modulus and high failure strain

Extremely low stiffness. Young’s Modulus is 106 Pa which is almost times lesser than metals

Able to be stretched to many times their starting length yet recover their initial shape when released

Strong and tough Example :- rubber, isoprene

GlassAmorphous solid which is often transparent

and has widespread practical,technological and decorative usage Hard Lack of crystal structure supresses plasticity Heat and electric insulator Corrosion resistant Transparent to light Brittle Example :- Sodalime Glass, pyrex glass

Strength vs density plot

Porous materialContaining pores that are usually filled with

a gas liquid while skeletal material is solid. Usually organic but nowadays inorganic materials have been synthesized

Pores deeper than wideCan be divided on basis of- Accessibility : closed pores, open pores,

blind pores and through pores- Shape : cylindrical open, cylindrical blind,

ink bottle shaped and funnel shaped

Hierarchy of metalluargic length scale

Atomic structure1) 0.1 to 1 nm2) Crystal structure3) Interface structure4) Yield strength5) Thermal stability

Microstructure1) 1 to 100 micro meter2) Yield strength3) Tensile strength4) Thermal stability

Nanostructure1) 1 to 100 nm2) Precipitates3) Grain boundaries4) Yield strength5) Low cycle fatigue6) Ductility7) Tensile strength8) Thermal stability