Fracture: Microstructural Aspects Assignment

Material Science and Enginering

Different Fracture Modes

Materials with Different Degrees of Brittleness

Ductile Fracture

(a) Failure by shear (glide) in a pure metal. (Reprinted with permission from D. Broek, Elementary Engineering Fracture Mechanics, 3rd ed. (The Hague, Netherlands: Martinus Nijhoff, 1982), p. 33.) (b) A point fracture in a soft single-crystal sample of copper. (Courtesy of J. D. Embury.)

Zener-Stroh Crack

Crack Nucleation in HCP Metals

a. Lattice rotation due to bend planes,b. Lattice rotation due to twinning,c. Crack nucleation in Zn due to lattice

rotation caused by bend planes. (Courtesy of J.J. Gilman.)

Microcrack Formation at Twins

Initiation of failure by microcrack formation in tungsten deformed at approximately 104 s−1 at room temperature. (a) Twin steps. (b) Twin steps and twin–twin intersection. (From T. Dümmer, J. C. LaSalvia, M. A. Meyers, and G. Ravichandran, Acta Mater., 46 (1998) 959.)

W-Type Cavitation

w-type cavitation at a grain-boundary triple point.

r-Type Cavitation

r-type cavitation at a grain boundary

Nucleation of a Cavity at a Second-PhaseParticle

Nucleation of a cavity at a second-phase particle in a ductile material. (Adapted with permission from B. R. Lawn and T. R. Wilshaw, Fracture of Brittle Solids (Cambridge: Cambridge University Press, 1975), p. 40.)

Dimple Fracture

Dimple fracture resulting from the nucleation, growth, and coalescence of microcavities. SEM. Note the inclusion, which served as the microcavity nucleation site.

Cup and Cone Fracture

Cup and Cone Fracture

Ductile Fracture by Void Nucleation, Growth, and Coalescence

Ductile Fracture Progression: TEM In-situ Results

Ductility vs. Volume Fraction of Second Phase

Ductility vs. volume fraction of second phase, f, for copper containing various second phase particles. The dashed line represents the prediction from the law of mixtures, assuming zero ductility for the second-phase particles. (From B. I. Edelson and W. J. Baldwin, Jr., Trans. ASM, 55 (1962) 230.)

Initiation of Void Growth by Dislocation Emission

Prismatic Loops Shear Loops

Ductile-Brittle Transition

Ductile–brittle transition in steel and the effect of loading rate.

Propagation of Transgranular Cleavage

Propagation of transgranular cleavage. (Adapted from J. R. Low, in Madrid Colloquium on Deformation and Flow of Solids (Berlin: Springer-Verlag, 1956), p. 60.)

Cleavage Facets

Formation of Cleavage Steps

Intergranular Fracture

Intergranular Fracture in Steel

Sources of Flaws in Ceramics

Brittle Failure by Axial Splitting

Compressive failure of a brittle material by axial splitting.