What is the key feature of the body-centered cubic (BCC) crystal structure?
A One atom at the center
B Dense packing
C Low thermal conductivity
D High ductility
The BCC crystal structure features an atom at the center of the unit cell and atoms at the corners. This structure is less densely packed compared to other structures, like FCC, and has good strength but low ductility.
Which of these metals is most commonly used in electrical wiring?
A Aluminum
B Steel
C Copper
D Brass
Copper is highly conductive and is commonly used in electrical wiring. It has a low resistance, high tensile strength, and excellent corrosion resistance, making it ideal for electrical applications.
What does the term “solid solution” mean in metallurgy?
A Liquid mixture of metals
B Alloys with gas
C Uniform mixture of metals
D No alloying elements
A solid solution is a homogeneous mixture of two or more elements, where one metal is dissolved in another at the atomic level. It is common in alloys, enhancing properties like strength and ductility.
What is the main characteristic of austenitic steel?
A Low ductility
B Non-magnetic
C High strength
D Magnetic
Austenitic steel, which contains a high percentage of chromium and nickel, is non-magnetic. It is widely used for its excellent corrosion resistance and good formability in various applications, including food processing.
What is the effect of cold working on materials?
A Increase ductility
B Decrease strength
C Increase hardness
D Increase brittleness
Cold working involves deforming a material at room temperature, which increases dislocations in the crystal structure, leading to increased hardness and strength but decreased ductility.
Which of the following is a high-temperature phase transformation in metals?
A Martensitic transformation
B Creep
C Melting
D Solidification
Martensitic transformation occurs in steels when heated to high temperatures and then rapidly cooled, resulting in a hard, brittle microstructure. It is a key transformation in hardening steels.
What type of material is commonly used in the manufacture of surgical implants?
A Steel
B Biomaterials
C Ceramics
D Polymers
Biomaterials, such as titanium alloys, are commonly used in medical implants due to their biocompatibility, strength, and resistance to corrosion in the human body.
What is the primary purpose of tempering steel?
A To increase strength
B To increase hardness
C To improve corrosion resistance
D To reduce brittleness
Tempering is a heat treatment process applied to steel after hardening to reduce brittleness and relieve internal stresses while maintaining strength. This process improves toughness and reduces the likelihood of failure.
What does the term “ductility” refer to in materials?
A Ability to undergo plastic deformation
B Ability to resist oxidation
C Resistance to fracture
D Ability to resist deformation
Ductility is a measure of a material’s ability to deform plastically without breaking. It is a critical property for materials used in manufacturing processes that require stretching or forming.
Which of the following is a characteristic of thermosetting polymers?
A Softens easily
B Can be reshaped
C Irreversibly hardened
D Reusable after heating
Thermosetting polymers, once hardened by heat, cannot be reshaped or remelted. They maintain their form and strength after curing and are used in applications requiring high durability.
Which property is tested by the Rockwell hardness test?
A Material’s resistance to indentation
B Material’s tensile strength
C Material’s fracture toughness
D Material’s creep resistance
The Rockwell hardness test measures the material’s resistance to indentation under a specific load. It provides an indication of hardness, which is essential for determining wear resistance and suitability for different applications.
Which material property is most important for selecting materials for high-pressure vessels?
A Ductility
B Hardness
C Yield strength
D Toughness
Yield strength is crucial for selecting materials for high-pressure vessels as it determines the material’s ability to withstand stress without permanent deformation. High yield strength ensures the material can handle high pressure safely.
What is a key advantage of powder metallurgy over traditional manufacturing methods?
A Low precision
B Limited material variety
C High energy consumption
D Complex shapes can be made
Powder metallurgy allows for the creation of complex shapes with minimal waste. It is highly precise and can produce intricate parts from materials that are difficult to shape using traditional methods.
What is the main function of a phase diagram in material science?
A To determine material costs
B To analyze chemical reactions
C To visualize material behavior under different conditions
D To predict the temperature at which a material will melt
Phase diagrams are graphical representations that show the phases of a material at different temperatures and compositions. They help in predicting phase transitions, such as solidification or melting, and guide material selection.
Which of the following is an example of a non-ferrous alloy?
A Brass
B Cast iron
C Mild steel
D Steel
Brass is an alloy of copper and zinc, and it is considered a non-ferrous alloy because it does not contain iron. Non-ferrous alloys are used for their corrosion resistance, conductivity, and malleability.