Last Minute Revision of Materials Science

• Hardness:- hardness is defined as a property of a material that resists any permanent (Plastic) deformation such as indentation, penetration, scratching, abrasion by harder bodies. It is measured by the resistance of the metal which it offers. The hardness of the metal is determined by comparing its hardness with ten standard materials.

• Toughness:- The total energy absorbed up to the fracture point is known as toughness. Toughness is also defined as the resistance of a material against failure. The tenacity and hardness of metal are the measures of its toughness. It has been found that the value of toughness falls with the temperature rise. The toughness of the material is indicated by the total area under the material tensile stress-strain curve up to the point of fracture.

• Stiffness:- Stiffness is defined as the resistance against plastic deformation. The modulus of elasticity is a measure of the stiffness of metal. The stiffness of metal has great importance while selecting it for a member or a component of a machine or a structure. It is also used in graduating spring balance and spring-controlled measuring instruments.

• Creep:- Creep is the phenomenon of losing mechanical property on a constant load by the function of temperature and time. It is important only at elevated temperatures. Generally, creeps occur in steel at higher temperatures. The creep is always considered while designing I.C. engines, Turbines, etc. Creep has great importance in the nuclear reactor field, white metal bearing, etc.

• Ductility:- The ability of a material to undergo plastic deformation without fracture, to convert in the form of wire on the application of tensile load. It depends upon the grain size of the metal crystals. Ductility may be expressed as percentage elongation or percentage area reduction. example:- Gold, platinum, silver, iron, copper, aluminum, etc.

• Brittleness:- Brittleness is defined as a material get fails without any significant permanent deformation then the material is called brittle material and property is called brittleness. A brittle material will fracture with little permanent deformation. A brittle material is hard and has little ductility. Cast iron, glass, and concrete are the example of brittle materials. 

• Stress:- It is defined as the force of resistance per unit area. It is the internal resistance set up by the molecules of a material to the deformation due to the application of external force.

• Strain:-  Strain is defined as a deformation per unit length of the body. It is also called an axial strain, linear strain, or longitudinal strain. 

• Plasticity:- If a material undergoes permanent deformation when loads are applicable or apply, then the phenomenon is called plasticity. plastically deformed material does not change dimension after removal of load.

• Elasticity:- If the material gets deform on the application of external load and regains its shape and size on the removal of load, then the material is called elastic material and the property is called elasticity. Example:- Rubber, etc.

• Resilience:- The capacity of a material to absorb energy within the elastic limit is known as resilience.

• Isotropy:- The material which shows the same mechanical property in every direction is known as isotropic material and the property is known as isotropy.

• Anisotropy:- If the material shows the variation in the property along a different direction, the material is called anisotropic material, and property is known as anisotropy.

• Strength:- Strength is a mechanical property of a material. It is defined as the ability to sustain failure under the action of the applied load.