Final answer:
Flaws or cracks in a material lead to stress concentrations, which can cause premature material failure. Line defects in metals, such as edge dislocations, are pertinent as they contribute to plastic deformation. Flaws and cracks do not directly decrease the elastic modulus, but they result in unpredictable material behavior under stress.
Step-by-step explanation:
The presence of flaws or cracks in a material generally leads to the development of stress concentrations. These imperfections can significantly affect the mechanical properties of materials, such as metals and ceramics. Stress concentrations are regions where stress is much higher than average, which can lead to premature failure of the material. For metals, the presence of line defects such as edge dislocations is particularly important as they can facilitate the movement and multiplication of dislocations, contributing to plastic deformation.
It is also essential to consider the thermal stresses that can occur during processes such as the coating of metals or metal expansion and contraction due to temperature changes. If not managed properly, these thermal stresses can further lead to cracks and flaws within the material. The elastic modulus is related to a material's ability to deform elastically; however, it should be noted that the presence of flaws does not directly decrease the material's elastic modulus but rather can lead to unpredictable and potentially hazardous material behavior under stress.