Which property is generally less in brittle materials compared to ductile materials?

Brittle materials are characterized by their lack of plastic deformation before failure, which fundamentally influences their toughness. Toughness is defined as the ability of a material to absorb energy and plastically deform without fracturing. It encompasses both strength and ductility; hence, materials that exhibit ductility, like many ductile metals, typically have higher toughness because they can undergo significant plastic deformation under stress.

In contrast, brittle materials tend to fracture suddenly with little to no prior deformation when subjected to stress. This abrupt failure indicates lower toughness because they are unable to absorb as much energy before breaking. Thus, while brittle materials may possess high yield and ultimate strengths, their incapacity for deformation results in significantly reduced toughness compared to ductile materials.

The other options relate to different mechanical properties: yield strength measures the stress at which a material begins to deform plastically, the elastic limit defines the maximum stress that a material can withstand without permanent deformation, and ultimate strength is the maximum stress a material can withstand before failure. These properties can vary widely in both brittle and ductile materials, but toughness is particularly distinct due to the inherent behaviors associated with brittleness and ductility.