What is the primary advantage of using alloys over pure metals?
A Improved hardness
B Increased brittleness
C Higher cost
D Better conductivity
Alloys are created by combining metals or adding other elements to improve properties such as hardness, strength, and corrosion resistance. This makes alloys more suitable for various engineering applications than pure metals.
Which of these is a common example of a ferrous alloy?
A Brass
B Aluminum
C Cast iron
D Bronze
Cast iron is a ferrous alloy, meaning it contains iron as its primary component. It is commonly used for making engine blocks and pipes due to its excellent castability and good wear resistance.
What is the primary purpose of adding chromium to steel?
A Decrease ductility
B Improve corrosion resistance
C Increase weight
D Improve strength
Adding chromium to steel creates stainless steel, which is highly resistant to corrosion due to the formation of a protective oxide layer. This is why stainless steel is used in kitchen utensils, medical equipment, and more.
Which microstructure feature is associated with the hardness of steel?
A Ferrite
B Pearlite
C Martensite
D Austenite
Martensite is a hard microstructure that forms when steel is rapidly cooled (quenched). It is known for its high hardness, making it ideal for cutting tools and wear-resistant components.
What is the effect of quenching on the microstructure of steel?
A Increased hardness
B Reduced strength
C Decreased hardness
D Increased ductility
Quenching involves heating steel to a high temperature and then rapidly cooling it. This process transforms the microstructure into martensite, which significantly increases hardness but can also reduce ductility.
Which material is commonly used in the construction of aircraft components?
A Bronze
B Steel
C Copper
D Aluminum
Aluminum is commonly used in aircraft construction due to its lightweight, high strength-to-weight ratio, and resistance to corrosion, making it ideal for aerospace applications where weight is a critical factor.
What is the primary property of polymer materials?
A High melting point
B High thermal conductivity
C Ability to stretch
D High hardness
Polymers, such as rubber, have the ability to stretch and return to their original shape, making them ideal for products that require flexibility and resilience, like seals, gaskets, and tires.
Which of the following is a property of composite materials?
A High strength-to-weight ratio
B High density
C High electrical conductivity
D High brittleness
Composite materials, such as fiberglass, are engineered to provide high strength while being lightweight. They are often used in aerospace, automotive, and sports equipment applications where both strength and low weight are essential.
Which material is used for making gears due to its wear resistance?
A Brass
B Bronze
C Aluminum
D Steel
Steel, especially hardened steel, is commonly used to make gears due to its wear resistance, toughness, and strength. It is ideal for applications involving continuous motion and high torque.
What is the primary function of annealing in metallurgy?
A Decrease ductility
B Relieve internal stresses
C Increase brittleness
D Increase hardness
Annealing is a heat treatment process used to relieve internal stresses in materials, soften them, and improve ductility. This is important in preventing brittle failure during further processing or use.
Which of the following is a typical property of ceramics?
A Low melting point
B High ductility
C High hardness and brittleness
D High thermal and electrical conductivity
Ceramics are known for their high hardness and resistance to wear but are also brittle. These properties make them ideal for applications such as cutting tools and insulators, though they are prone to cracking under impact.
What is the primary purpose of using a phase diagram in material selection?
A To predict phase changes at different temperatures and compositions
B To estimate the melting point
C To analyze fracture toughness
D To determine the chemical composition
Phase diagrams are used to predict how materials will behave at different temperatures and compositions. They are essential for selecting materials that will perform well under specific conditions, such as in casting or heat treatment processes.
Which type of alloy is commonly used for marine applications?
A Stainless steel
B Aluminum
C Brass
D Bronze
Bronze, particularly copper-tin alloys, is often used in marine applications due to its excellent resistance to corrosion in saltwater environments. It is commonly used in propellers, ship fittings, and underwater structures.
What is the main characteristic of ductile fracture in materials?
A High energy absorption
B Formation of cracks
C Significant plastic deformation
D Sudden breaking
Ductile fracture occurs when a material undergoes significant plastic deformation before breaking. It is characterized by the material stretching and forming necks before failing, indicating high toughness and energy absorption.
What is the main benefit of using powder metallurgy in manufacturing?
A Low production cost
B High precision and complex shapes
C Slow production time
D High material wastage
Powder metallurgy allows the production of complex shapes with high precision and minimal waste. It is ideal for manufacturing parts that would be difficult or expensive to make using traditional casting or machining methods.