The unit cell is the smallest repeating structure in a crystal lattice, representing the entire crystal structure when repeated in three dimensions. It defines the arrangement of atoms in a crystal.
Which type of bond is predominant in metals?
A Metallic
B Covalent
C Hydrogen
D Ionic
Metallic bonds are formed when metal atoms share their free electrons, allowing for electrical conductivity and malleability. This bond type is characteristic of metals and gives them their properties.
What does the phase diagram of a material represent?
A Material hardness
B Crystal defects
C Relationship between temperature and composition
D Heat treatment processes
A phase diagram shows the different phases (solid, liquid, gas) of a material at various temperatures and compositions. It is crucial for understanding the behavior of materials under different conditions.
Which heat treatment process involves heating a material and then cooling it rapidly?
A Hardening
B Quenching
C Annealing
D Tempering
Quenching is a heat treatment process where a material is heated to a specific temperature and then rapidly cooled, typically in water or oil, to increase hardness.
What is the main purpose of alloying metals?
A To reduce cost
B To make it more brittle
C To improve strength
D To increase weight
Alloying metals involves adding other elements to enhance properties like strength, corrosion resistance, and hardness. Common alloys include steel (iron and carbon) and brass (copper and zinc).
Which of the following materials is a ceramic?
A Plastic
B Steel
C Copper
D Glass
Ceramics are inorganic, non‐metallic materials, and glass is a common example. Ceramics are known for their hardness, high melting points, and brittleness.
Which phase transformation occurs when a metal solidifies from liquid to solid?
A Solidification
B Tempering
C Precipitation
D Annealing
Solidification is the process by which a liquid material cools and forms a solid structure. It is a key phase transformation that occurs during casting processes.
What is the primary property that defines the toughness of a material?
A Ductility
B Hardness
C Fracture toughness
D Creep resistance
Fracture toughness refers to a material’s ability to resist crack propagation. It is a crucial property for materials used in structural applications where safety is important.
Which material is commonly used for electrical applications due to its conductivity?
A Wood
B Copper
C Steel
D Rubber
Copper is an excellent conductor of electricity and is widely used in electrical wiring and electronic components due to its low resistance and high conductivity.
What type of polymer is used to make plastic bottles?
A Composite
B Thermoset
C Elastomer
D Thermoplastic
Thermoplastic polymers, such as polyethylene (PET), are used for plastic bottles. They can be melted and reshaped multiple times, which makes them ideal for manufacturing processes.
Which material is a common example of a composite?
A Concrete
B Silicon
C Wood
D Aluminum
Concrete is a composite material made of cement, water, and aggregates like sand or gravel. It is strong in compression but weak in tension, which is why steel reinforcement is often used.
What is the primary mechanism of fatigue failure in materials?
A High temperature
B Cyclic loading
C Chemical reaction
D Thermal expansion
Fatigue failure occurs when a material is subjected to repeated or cyclic loading, leading to the initiation and propagation of cracks over time, even if the stresses are below the material’s ultimate strength.
Which steel alloy is primarily used for making tools?
A Cast iron
B High-carbon steel
C Mild steel
D Stainless steel
High-carbon steel contains a high percentage of carbon, making it hard and strong. It is commonly used in tools, knives, and other high-wear applications due to its hardness and wear resistance.
Which of these is a non-ferrous alloy?
A Brass
B Carbon steel
C Cast iron
D Steel
Non-ferrous alloys, such as brass, do not contain significant amounts of iron. Brass is an alloy of copper and zinc, known for its corrosion resistance and use in plumbing and electrical fittings.
Which property measures a material’s resistance to indentation?
A Toughness
B Hardness
C Ductility
D Strength
Hardness refers to a material’s resistance to deformation, typically measured by its ability to resist indentation. It is a critical property for materials used in cutting tools and abrasion-resistant surfaces.