ABSTRACT
Figure 5.1 schematically illustrates three of the most common fracture mechanisms in metals and alloys. (A fourth mechanism, fatigue, is discussed in Chapter 10.) Ductile materials (Figure 5.1(a)) usually fail as the result of nucleation, growth, and the coalescence of microscopic voids that initiate at inclusions and second-phase particles. Cleavage fracture (Figure 5.1(b)) involves separation along specific crystallographic planes. Note that the fracture path is transgranular. Although cleavage is often called brittle fracture, it can be preceded by large-scale plasticity and ductile crack growth. Intergranular fracture (Figure 5.1(c)), as its name implies, occurs when the grain boundaries are the preferred fracture path in the material.
