A high fracture toughness indicates what in relation to metals?

A high fracture toughness in metals indicates that the material can withstand the propagation of cracks and other flaws without failing. This property is essential in applications where the material might be subject to impact, stress, or rapid changes in load. Consequently, high fracture toughness contributes to corrosion fatigue resistance, as materials that absorb energy and prevent the spread of cracks can better resist the combined effects of corrosive environments and cyclic loading.

Materials with high fracture toughness can endure more significant amounts of stress and deformation before they fracture, which is particularly important in industries where reliability and safety are critical, such as aerospace and structural engineering. This performance in challenging environments makes option B the correct choice in understanding the characteristics associated with high fracture toughness in metals.

Other options relate to different properties of metals that do not directly connect to fracture toughness, such as conductivity or thermal expansion, which focus on other material behaviors.