ME Material Properties and Testing 3

Question 1

The fracture toughness parameter K_IC represents:

Accepted Answer

Critical stress intensity factor for Mode I fracture

Answer

K_IC is the plane-strain fracture toughness, representing the critical stress intensity factor at which a Mode I (opening) crack will propagate catastrophically.

Question 2

A material with high strength but low ductility is best described as:

Accepted Answer

Brittle

Answer

Brittle materials have high strength but fracture with little plastic deformation, resulting in low toughness and ductility.

Question 3

X-ray diffraction (XRD) is primarily used to determine a material's:

Accepted Answer

Crystal structure and lattice parameters

Answer

XRD identifies crystalline phases, crystal structure, and lattice parameters by analyzing the diffraction pattern produced when X-rays interact with the atomic lattice.

Question 4

Creep in materials is most significant at temperatures above approximately what fraction of the melting point (in Kelvin)?

Accepted Answer

0.5 T_m

Answer

Creep becomes significant above approximately 0.3-0.5 T_m (homologous temperature), where thermally activated diffusion mechanisms drive time-dependent deformation.

Question 5

Which type of fracture surface appears rough and fibrous, indicating significant plastic deformation?

Accepted Answer

Ductile fracture

Answer

Ductile fracture surfaces are rough and fibrous due to microvoid coalescence and significant plastic deformation before failure.

ME - Materials Engineer Practice Test

ME - Materials Engineer Practice Test

ME Material Properties and Testing 3