Materials Science Flashcards

The Charpy impact test is used to measure a material's:

Answer: Notch toughness

The Charpy test measures impact energy absorbed by a notched specimen, characterizing the material's notch toughness and susceptibility to brittle fracture.

Austenite in steel is the FCC phase stable above approximately:

Answer: 727°C

For plain-carbon steels, austenite (FCC iron) becomes stable above the eutectoid temperature of approximately 727°C (A1 line on the Fe-C diagram).

Which process involves heating steel above the critical temperature and then cooling it in still air?

Answer: Normalizing

Normalizing consists of austenitizing steel and allowing it to air-cool, producing a finer, more uniform pearlitic microstructure than full annealing.

Galvanic corrosion occurs when two dissimilar metals are in electrical contact in the presence of an electrolyte. Which metal corrodes preferentially?

Answer: The more active (anodic) metal

In a galvanic couple, the more active (less noble) metal acts as the anode and undergoes preferential oxidation and corrosion.

The glass transition temperature (Tg) of a polymer is the temperature at which:

Answer: The amorphous regions transition from glassy to rubbery behavior

At Tg, the amorphous phase of a polymer transitions from a rigid, glassy state to a soft, rubbery state as chain mobility increases.

Which failure mode is characterized by crack growth under cyclic loading at stresses well below the yield strength?

Answer: Fatigue failure

Fatigue failure occurs due to progressive crack initiation and growth under repeated cyclic loading, often at stresses far below the static yield strength.

Fick's second law of diffusion describes how:

Answer: Concentration profile changes with time during non-steady-state diffusion

Fick's second law (∂C/∂t = D ∂²C/∂x²) governs the time-dependent change in concentration distribution during transient (non-steady-state) diffusion.