Metals and Alloys Flashcards
6 cards from real ME practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Metals and Alloys flashcards as text
Superalloys used in jet engine turbine blades are primarily based on which metal system?
Answer: Nickel-based alloys
Nickel-based superalloys are the dominant material for turbine blades due to their exceptional high-temperature strength, creep resistance, and oxidation resistance.
The titanium alloy Ti-6Al-4V is classified as which type of alloy?
Answer: Alpha-beta alloy
Ti-6Al-4V is the most widely used titanium alloy and is an alpha-beta alloy, containing aluminum (alpha stabilizer) and vanadium (beta stabilizer).
Solid solution strengthening occurs when solute atoms:
Answer: Distort the lattice and impede dislocation motion
Solute atoms cause local lattice distortions that create stress fields, increasing the resistance to dislocation movement and thus strengthening the material.
Which phenomenon causes low-carbon steels to exhibit an upper and lower yield point on the stress-strain curve?
Answer: Luders band formation due to interstitial carbon/nitrogen pinning dislocations
In low-carbon steels, interstitial carbon and nitrogen atoms pin dislocations; the upper yield point is the stress to unpin dislocations, and the lower yield point is the stress to propagate Luders bands.
Work hardening (strain hardening) increases a metal's strength by:
Answer: Increasing dislocation density
Cold working increases dislocation density; as dislocations multiply and interact, they impede each other's motion, requiring higher stresses for further deformation.
In aluminum alloys, the T6 temper designation indicates:
Answer: Solution heat treated and artificially aged
The T6 temper in aluminum alloys means the material has been solution heat treated and then artificially aged (typically at 160-180 degrees C) to peak hardness.