What change occurs in materials with low toughness?

Materials with low toughness are characterized by their inability to absorb significant energy before failing. Toughness is the measure of a material's ability to withstand both elastic and plastic deformations and absorb energy before fracturing. When subject to sudden stress, materials with low toughness do not have the capacity to deform significantly and thus are more likely to fracture almost immediately. This is because there is insufficient energy absorption before the material reaches its breaking point.

In contrast, materials that are tougher can withstand higher amounts of stress and energy, allowing them to deform substantially before ultimately breaking, which is not the case for those with low toughness. The tendency to fracture without significant deformation makes low-toughness materials particularly susceptible to breaking under sudden impacts or loads.